First_Aid_Step2

First_Aid_Step2. They can be time consuming and expensive. Studies assess only the relationship of the disease to the few exposure factors recorded at the start of the study. They require many subjects and are thus ineffcient and cannot be used to study rare diseases. Cohort studies may be prospective—in which a cohort is assembled in the present and followed into the future—or they may be retrospective, in which a cohort is identifed from past records and followed to the present. Case-control studies are essentially cohort studies in reverse. In such studies, a researcher selects two groups—one with disease (cases) and one without (controls)—and then looks back in time to measure the comparative frequency of exposure to a possible risk factor in the two groups. The validity of a case-control study depends on appropriate selection of cases and controls, the manner in which exposure is measured, and the manner in which extraneous variables (confounders) are dealt with.


First_Aid_Step2

First_Aid_Step2. Cases and controls should be comparable in terms of opportunity for exposure (i.e., they should be members of the same base population with an equal opportunity of risk factor exposure). Cases should be newly diagnosed using explicit criteria for diagnosis. Exposures should be assessed in as unbiased a fashion as possible. Confounding may be ↓ by matching subjects or through the stratif cation of subjects. Multivariable analysis may be helpful in this context. Advantages of such studies are as follows: Studies use small groups, thereby reducing expense. They can be used to study rare diseases and can easily examine multiple risk factors. Disadvantages include the following: Studies cannot calculate disease prevalence, incidence, or relative risk, because the numbers of subjects with and without a disease are determined artifcially by the investigator rather than by nature (an odds ratio can be used to estimate relative risk).


First_Aid_Step2

First_Aid_Step2. Retrospective data may be inaccurate owing to recall or survivorship biases. If alcohol intake among individuals with breast cancer is compared with that of individuals without breast cancer, think case-control study. Absolute risk: The number of finger injuries among hospital staff this week. There are several ways to express and compare risk. These include the following: Absolute risk: Defned as the incidence of disease. Attributable risk (or risk difference): The additional incidence of disease that is due to a risky exposure, on top of the background incidence from other causes. Attributable risk = Incidence of disease in exposed – Incidence in unexposed Relative risk (or risk ratio): Expresses how much more likely an exposed person is to get disease in comparison to an unexposed person. This indicates the strength of the association between exposure and disease, making it useful when one is considering disease etiology.


First_Aid_Step2

First_Aid_Step2. ■ Odds ratio: An estimate of relative risk that is used in case-control studies. The odds ratio tells how much more likely it is that a person with a disease has been exposed to a risk factor than someone without the disease. The Attributable risk: (number of injuries among staff who used scissors) – (number of injuries among staff who did not use scissors). Relative risk: (number of injuries among staff who used scissors) ÷ (number of injuries among staff who did not use scissors). F IGU R E 2.4-2. Relative risk (RR) vs. odds ratio (OR). lower the disease incidence, the more closely it approximates relative risk (see Figure 2.4-2). Odds that a diseased person is exposed Odds ratio = Odds that a nondiseased person is exposed Odds ratio: (odds that injured staff used scissors) ÷ (odds that uninjured staff used scissors).


First_Aid_Step2

First_Aid_Step2. Odds that a diseased person is exposed Odds ratio = Odds that a nondiseased person is exposed Odds ratio: (odds that injured staff used scissors) ÷ (odds that uninjured staff used scissors). Once a diagnosis has been established, it is important to be able to describe the associated prognosis. Survival analysis is used to summarize the average time from one event (e.g., presentation, diagnosis, or start of treatment) to any outcome that can occur only once during follow-up (e.g., death or recurrence of cancer). The usual method is with a Kaplan-Meier curve (see Figure 2.4-3) describing the survival (or time-to-event if the measured outcome is not death) in a cohort of patients, with the probability of survival de Probability of event creasing over time as patients die or drop out (are censored) from the study. Odds = 1 − probability of


First_Aid_Step2

First_Aid_Step2. Probability of event creasing over time as patients die or drop out (are censored) from the study. Odds = 1 − probability of Studies are typically used to judge the best treatment for a disease. Although the gold standard for such evaluation is a randomized, double-masked controlled trial, other types of studies may be used as well (e.g., an observational F IGU R E 2.4-3. Example of a Kaplan-Meier curve. study, in which the exposure in question is a therapeutic intervention). In descending order of quality, published studies regarding treatment options include meta-analyses, randomized controlled trials, and case series/case reports.


First_Aid_Step2

First_Aid_Step2. A randomized controlled trial is an experimental, prospective study in which subjects are randomly assigned to a treatment or control group. Random assignment helps ensure that the two groups are truly comparable. The control group may be treated with a placebo or with the accepted standard of care. The study may be masked in one of two ways: single-masked, in which patients do not know which treatment group they are in, or double-masked, in which neither the patients nor their physicians know who is in which group. Double-masked studies are the gold standard for studying treatment effects. Advantages of randomized controlled trials are as follows: They involve minimal bias. They have the potential to demonstrate causal relationships. Disadvantages include the following: They are costly and time intensive. Informed consent may be diffcult to obtain. Some interventions (e.g., surgery) are not amenable to masking. Ethical standards cannot allow all variables to be controlled.


First_Aid_Step2

First_Aid_Step2. Informed consent may be diffcult to obtain. Some interventions (e.g., surgery) are not amenable to masking. Ethical standards cannot allow all variables to be controlled. Def ned as any process that causes results to systematically differ from the truth. Good studies and data analyses seek to minimize potential bias. Types of bias include the following: Selection bias: Occurs when samples or participants are selected that differ from other groups in additional determinants of outcome. Examples: A surgeon may select patients without signifcant comorbid conditions to receive surgery, resulting in unexpectedly positive outcomes compared to previous studies. Similarly, individuals concerned about a family history of breast cancer may be more likely to self-select in entering a mammography program, giving the impression of a prevalence that is higher than reality.


First_Aid_Step2

First_Aid_Step2. Measurement bias: Occurs when measurement or data-gathering methods differ between groups. Example: One group is assessed by CT while another group is assessed by MRI. Confounding bias: Occurs when a third variable is associated with both the dependent variable and the independent variable (either positively or negatively), inducing a falseassociation (type I bias). Example: Fishermen in an area may experience a higher incidence of cataracts than the general population. However, becoming a fsherman will not in itself give you cataracts; rather, it is the sunlight to which those fshermen are exposed in their outdoor work. Recall bias: Results from a difference between two groups in the retrospective recall of past factors or outcomes. Example: A patient with cancer may be more motivated than a healthy individual to recall past episodes of chemical exposure.


First_Aid_Step2

First_Aid_Step2. Lead-time bias: Results from earlier detection of disease, giving an appearance of prolonged survival when in fact the natural course is not altered. Example: A new and widely used screening test that detects cancer f ve Randomization minimizes bias and confounding; double-blinded studies prevent observation bias. Studies that are masked and randomized are better protected from the effects of bias, whereas observational studies are particularly susceptible to bias. Confounding variables reduce the internal validity of a study. years earlier may give the impression that patients are living longer with the disease.


First_Aid_Step2

First_Aid_Step2. Confounding variables reduce the internal validity of a study. years earlier may give the impression that patients are living longer with the disease. ■ Length bias: Occurs when screening tests detect a disproportionate number of slowly progressive diseases but miss rapidly progressive ones, leading to overestimation of the beneft of the screen. Example: A better prognosis for patients with cancer is celebrated after implementation of a new screening program. However, this test disproportionally detects slow-growing tumors, which generally tend to be less aggressive. Even with bias reduction, unsystematic random error is unavoidable owing to chance variation in studied data. Types of errors are as follows: Type I (α) error: Defned as the probability of saying that there is a difference in treatment effects between groups when in fact there is not (i.e., a false-conclusion).


First_Aid_Step2

First_Aid_Step2. Type I (α) error: Defned as the probability of saying that there is a difference in treatment effects between groups when in fact there is not (i.e., a false-conclusion). The p-value is an estimate of the probability that differences in treatment effects in a study could have happened by chance alone. Classically, differences associated with a p < 0.05 are statistically signif cant. Type II (β) error: Defned as the probability of saying that there is no difference in treatment effects (i.e., a falseconclusion) when in fact a difference exists. Power is the probability that a study will fnd a statistically signif cant difference when one is truly there. It relates directly to the number of subjects. Power (β) = 1 – type II error. The confidence interval (CI) is a way of expressing statistical signif cance (p-value) that shows the size of the effect and the statistical power. CIs are interpreted as follows:


First_Aid_Step2

First_Aid_Step2. The confidence interval (CI) is a way of expressing statistical signif cance (p-value) that shows the size of the effect and the statistical power. CIs are interpreted as follows: If one is using a 95% CI, there is a 95% chance that the interval contains the true effect size, which is likely to be closest to the point estimate near the center of the interval. Example: You would like to estimate the percentage of women with a specifc disease. A 10% result from a sample of 3000 women would provide a 95% CI of 9%–11%, whereas a 10% f nding from a sample of 30 women would yield a CI of –1% of 21%. The frst case has more power because the sample size is larger, producing a narrow interval. In the latter case, you cannot state with 95% certainty that women in general even have the disease! If the CI includes the value corresponding to a relative risk of 1.0 (i.e., zero treatment difference), the results are not statistically signif cant. If the CI is wide, power is low.


First_Aid_Step2

First_Aid_Step2. If the CI includes the value corresponding to a relative risk of 1.0 (i.e., zero treatment difference), the results are not statistically signif cant. If the CI is wide, power is low. ■There are three levels of prevention: 1° prevention: Includes measures to ↓ the incidence of disease. 2° prevention: Focuses on identifying the disease early, when it is asymptomatic or mild, and implementing measures that can halt or slow disease progression. 3° prevention: Includes measures that ↓ morbidity or mortality resulting from the presence of disease. TABLE 2.4-1. Types of Vaccinations Live attenuated Measles, mumps, rubella, polio (Sabin), yellow fever, inﬂuenza (nasal spray). Inactivated (killed) Cholera, inﬂuenza, HAV, polio (Salk), rabies, inﬂuenza (injection). Toxoid Diphtheria, tetanus. Subunit HBV, pertussis, Streptococcus pneumoniae, HPV, meningococcus. Conjugate Hib, S. pneumoniae.


First_Aid_Step2

First_Aid_Step2. Prevention may be accomplished by a combination of immunization, chemoprevention, behavioral counseling, and screening. A good screening test has the following characteristics: It has high sensitivity and specifcity. It has a high PPV. It is inexpensive, easy to administer, and safe. Treatment after screening is more effective than subsequent treatment without screening. Vaccines work by mimicking infections and triggering an immune response in which memory cells are formed to recognize and fght any future infection. There are several different vaccine formulations, as indicated in Table 2.4-1. Recommended vaccination schedules for children and adults are outlined in Figures 2.4-4 through 2.4-6. 1° prevention: A woman reduces dietary intake of fat or alcohol to reduce her risk of developing breast cancer. 2° prevention: A woman obtains a mammogram to screen for breast cancer. 3° prevention: A woman undergoes surgical intervention for breast cancer.


First_Aid_Step2

First_Aid_Step2. 2° prevention: A woman obtains a mammogram to screen for breast cancer. 3° prevention: A woman undergoes surgical intervention for breast cancer. Diphtheria, Tetanus, Pertussis Range of recommended Measles, Mumps, Rubella Varicella Hepatitis A Meningococcal F IGU R E 2.4-4. Recommended vaccinations for children 0–6 years of age. (Reproduced from the Centers for Disease Control and Prevention, Atlanta, Georgia.) F IGU R E 2.4-5. Recommended vaccinations for children 7–18 years of age. Range of recommended ages (Reproduced from the Centers for Disease Control and Prevention, Atlanta, Georgia.)


First_Aid_Step2

First_Aid_Step2. Range of recommended ages (Reproduced from the Centers for Disease Control and Prevention, Atlanta, Georgia.) VACCINE AGE GROUP 19–26 years 27–49 years 50–59 years 60–64 years >65 years Tetanus, diphtheria, pertussis (Td/Tdap)* Human papillomavirus (HPV)* Measles, mumps, rubella (MMR) * Influenza* Pneumococcal (polysaccharide) Hepatitis A* Hepatitis B* Meningococcal* Zoster Varicella * 3 doses 1 or more doses 2 doses 1 or 2 doses 1 dose 3 doses (females) Substitute 1-time dose ofTdap forTd booster; then boost withTd every 10 yrs 2 doses 1 or 2 doses 1 dose 1 dose *Covered by the Vaccine Injury Compensation Program. For all persons in this category who meet the age requirements and who lack evidence of immunity No recommendationRecommended if some other risk factor is present (e.g., on the basis of medical, 1 dose ann u all y Td booster every 10 yrs (e.g., lack documentation of vaccination or have occupational, lifestyle, or other indications) no evidence of prior infection)


First_Aid_Step2

First_Aid_Step2. F IGU R E 2.4-6. Recommended vaccinations for adults. (Reproduced from the Centers for Disease Control and Prevention, Atlanta, Georgia.) T AB LE 2.4-2. Stages of Change in Behavioral Counseling


First_Aid_Step2

First_Aid_Step2. Precontemplation Denial or ignorance of the problem. A 51-year-old smoker has not even thought about cessation. Contemplation Ambivalence or conﬂicted emotions; assessing benefits and barriers to change. A 43-year-old crack cocaine addict considers treatment for her addiction. Preparation Experimenting with small changes; collecting information about change. A 28-year-old heroin addict visits his doctor to ask questions about quitting. Taking direct action toward achieving a goal. A 33-year-old enters a rehabilitation facility for treatment of addiction to prescription narcotics. Maintaining a new behavior; avoiding temptation. A 41-year-old continues to visit Alcoholics Anonymous meetings to gain support and reinforcement against relapse. Action Maintenance ■Live vaccines should not be administered to immunosuppressed patients. Such vaccines are also contraindicated in pregnant women owing to a theoretical risk of maternal-fetal transmission.


First_Aid_Step2

First_Aid_Step2. Defned as the use of drugs to prevent disease. Examples include supplementation of water and food with healthful vitamins and minerals; aspirin prophylaxis for heart disease; statin treatment for hypercholesterolemia; and perioperative β-blockade. In offering counsel, physicians should tailor their education and suggestions to the individual patient as well as to his or her stage of change (see Table 2.4-2). Counseling is most likely to be successful when it accommodates the patient’s willingness to change or lack thereof. Tables 2.4-3 and 2.4-4 outline recommended health care screening measures by age group and modality. T AB LE 2.4-3. Health Screening Methods by Age


First_Aid_Step2

First_Aid_Step2. T AB LE 2.4-3. Health Screening Methods by Age Birth–10 years Height and weight, BP, vision and hearing screening, hemoglobinopathy screen (at birth), phenylalanine level (at birth), TSH and/or T4 (at birth), lead level (at least one time before six years of age). 11–24 years Height and weight, BP, Pap test, gonorrhea and chlamydia (GC) screen (if sexually active), rubella serology or vaccination (women only); screen for risky behaviors, including substance abuse. 25–64 years Height and weight, BP (every two years), cholesterol (every five years), Pap test and bimanual pelvic exam, fecal occult blood test (FOBT) or fecal immunochemical test (FIT), sigmoidoscopy or colonoscopy, mammography, rubella serology or vaccination (women only); screen for alcohol abuse and depression. ≥ 65 years Height and weight, BP, FOBT or FIT, sigmoidoscopy or colonoscopy, Pap test, vision and hearing screening, osteoporosis (DEXA) scans for women; screen for alcohol abuse and depression.


First_Aid_Step2

First_Aid_Step2. T AB LE 2.4-4. Health Screening Methods by Modality Once every 10 years in patients ≥ 50 years of age (or ≥ 40 years of age for high-risk patients). The preferred modality if there is a known history of dysplasia. CT virtual colonoscopy is comparable to standard colonoscopy and can be used every five years as an initial screening exam. Once every year within three years after onset of vaginal intercourse, but no later than age 21 up to age 30; once every two years with liquid-based Pap test. The interval can be ↑ to once every 2–3 years for women > 30 years of age with three cytology tests. Offer every three years to female patients in 20s and 30s, and every year to females 40 or more years of age (controversial). a Different medical societies have various recommendations regarding cancer screening. Refer to the National Cancer Institute’s Web site for a recent summary of recommendations: www.nci.nih.gov/cancer_information/testing.


First_Aid_Step2

First_Aid_Step2. Colonoscopy Flexible sigmoidoscopy Once every five years in patients ≥ 50 years of age (or ≥ 40 years of age for high-risk patients). FOBT or FIT Once every year in patients ≥ 50 years of age (or ≥ 40 years of age for high-risk patients). Bimanual pelvic exam Once every 1–3 years in patients 20–40 years of age; once yearly in patients ≥ 40 years of age. Pap test Mammography Once every 1–2 years in patients ≥ 40 years of age; once yearly in patients ≥ 50 years of age (controversial). Endometrial tissue sampling Not recommended as a screening test; indicated for postmenopausal bleeding. CXR Not recommended as a screening test. Skin exam Insufficient evidence. DRE Offer every year to high-risk patients at 40 years and to others at 50 years of age (controversial). PSA Offer every year to high-risk patients at 40 years and to others at 50 years of age (controversial). Clinical breast exam


First_Aid_Step2

First_Aid_Step2. The leading cause of cancer mortality in the United States is lung cancer. Prostate and breast cancers are the most prevalent cancers in men and women, respectively, with lung and colorectal cancers ranking second and third most common in both sexes. Table 2.4-5 lists the principal causes of death in the United States by age group. TABLE 2.4-5. Leading Causes of Death by Age Group


First_Aid_Step2

First_Aid_Step2. TABLE 2.4-5. Leading Causes of Death by Age Group All ages Heart disease, cancer, stroke, chronic lower respiratory disease, injuries, diabetes. < 1 year Congenital anomalies, disorders related to low birth weight, SIDS, maternal complications. 1–4 years Injuries, congenital anomalies, cancer, homicide, heart disease. 5–14 years Injuries, cancer, congenital anomalies, homicide, suicide, heart disease. 15–24 years Injuries, homicide, suicide, cancer, heart disease. 25–44 years Injuries, cancer, heart disease, suicide, HIV, homicide. 45–64 years Cancer, heart disease, injuries, stroke, diabetes, chronic lower respiratory disease. ≥ 65 years Heart disease, cancer, stroke, chronic lower respiratory disease, Alzheimer’s disease, diabetes. Adapted, with permission, from the National Center for Health Statistics, Department of Health and Human Services, www.cdc.gov/nchs.


First_Aid_Step2

First_Aid_Step2. By law, disease reporting is mandated at the state level, and the list of diseases that must be reported to public health authorities varies slightly by state. The CDC has a list of nationally notifable diseases that states voluntarily report to the CDC. These diseases include but are not limited to those listed in Table 2.4-6. T AB LE 2.4-6. Common Reportable Diseases


First_Aid_Step2

First_Aid_Step2. T AB LE 2.4-6. Common Reportable Diseases STDs HIV, AIDS, syphilis, gonorrhea, chlamydia, chancroid, HCV. Tick-borne disease Lyme disease, ehrlichiosis, Rocky Mountain spotted fever. Potential bioweapons Anthrax, smallpox, plague. Vaccine-preventable disease Diphtheria, tetanus, pertussis, measles, mumps, rubella, polio, varicella, HAV, HBV, H. inﬂ uenzae (invasive), meningococcal disease. Water-/food-borne disease Cholera, giardiasis, legionella, listeriosis, botulism, shigellosis, shiga toxin–producing E. coli, salmonellosis, trichinellosis, typhoid. Zoonoses Tularemia, psittacosis, brucellosis, rabies. Miscellaneous TB, leprosy, toxic shock syndrome, SARS, West Nile virus, VRSA, coccidioidomycosis, cryptosporidiosis. Confidentiality 149 Conﬂict of Interest 149 Malpractice 150


First_Aid_Step2

First_Aid_Step2. Confidentiality 149 Conﬂict of Interest 149 Malpractice 150 Respect for autonomy: Clinicians are obligated to respect patients as individuals and to honor their preferences in medical care. Example: A surgeon presents the risks and benefits of tumor resection to her patient before consent is given to proceed with the procedure. Beneficence: Physicians have a responsibility to act in the patient’s best interest. As a fiduciary, the physician stands in a special relationship of trust and responsibility to patients. Respect for patient autonomy may conﬂ ict with beneficence. Example: An elderly woman is adamant that she does not want to go to a rehabilitation facility and thus refuses amputation of a potentially gangrenous foot. The procedure is necessary to prevent life-threatening complications. The physician has a responsibility to act in the patient’s best interest.


First_Aid_Step2

First_Aid_Step2. Nonmaleficence: “Do no harm.” The responsibility to avert avoidable harms is a strong duty. However, if the potential benefits of an intervention outweigh the risks, an autonomous patient may make an informed decision to consent and proceed. Example: A patient may choose to undergo dialysis, accepting that his discomfort would be outweighed by the greater good of sustaining life. Justice: With regard to individual patients, fairness is expressed as the notion that equal persons should be treated equally. Health care is an important resource, and access to quality health care gives individuals a greater chance for a healthy and productive life. Fair distribution of this resource is an ongoing challenge for health policy and in the clinical arena.


First_Aid_Step2

First_Aid_Step2. Defined as willing acceptance (without coercion) of a medical intervention by a patient after adequate discussion with a physician about the nature of the intervention along with its indications, risks, benefits, and potential alternatives (including no treatment). Patients may change their minds at any time. Informed consent is required for significant procedures unless: Emergency treatment is required. Examples: An unconscious patient presents with cerebral edema after a motor vehicle collision, or a patient without previously indicated DNR/DNI status undergoes cardiac arrest. Patients lack decision-making capacity (consent can be obtained from a surrogate decision maker). Examples: Patients may present with dementia or significant psychiatric disturbances. Minors generally require surrogate decision makers until they demonstrate adequate decision-making capacity or are of legal age.


First_Aid_Step2

First_Aid_Step2. Consent for treatment is implied in life-threatening situations when parents cannot be contacted. Emancipated minors do not require parental consent for medical care. Minors are emancipated if they are married, in the armed services, or are financially independent of their parents and have sought legal emancipation.


First_Aid_Step2

First_Aid_Step2. Minors may consent to care for sexually transmitted infections without parental consent or knowledge. Rules concerning contraception, preg nancy, and abortion services and treatment for drug and alcohol dependency vary across the United States. (Some states leave the decision of informing parents about adolescent use of confidential services to the physician, based on the best interest of the patient. Other states limit disclosure.) ■Refusal of treatment: A parent has the right to refuse treatment for his/her child as long as those decisions do not pose a serious threat to the child’s well-being (e.g., refusing immunizations is not considered a serious threat). If a decision is not in the best interest of the child, a physician may seek a court order to provide treatment against parental wishes. In emergent situations, if withholding treatment jeopardizes the child’s safety, treatment can be initiated on the basis of legal precedent. Example: A physician provides blood transfusion to


First_Aid_Step2

First_Aid_Step2. wishes. In emergent situations, if withholding treatment jeopardizes the child’s safety, treatment can be initiated on the basis of legal precedent. Example: A physician provides blood transfusion to save the life of a six-year-old child seriously injured in a motor vehicle collision despite parental requests to withhold such a measure.


First_Aid_Step2

First_Aid_Step2. Minors may consent to care for sexually transmitted infections without parental consent or knowledge. Competence: Refers to a person’s legal capacity to make decisions and be held accountable in a court of law. Competence is assessed by the courts and is often used interchangeably with the term decision-making capacity (see below). Decision-making capacity: A medical term that refers to the ability of a patient to understand relevant information, appreciate the severity of the medical situation and its consequences, communicate a choice, and deliberate rationally about one’s values in relation to the decision being made. This can be assessed by the physician. Decision-making capacity is best understood as varying with the complexity of the decision involved. Example: The level of capacity needed for a decision about liver transplantation is different from that needed to choose between two types of pain medication for fracture-related pain.


First_Aid_Step2

First_Aid_Step2. Incompetent patients, as assessed by the courts, or temporarily incapacitated patients cannot decide to accept or refuse treatment. Example: An intoxicated patient with altered mental status cannot refuse thiamine supplementation. In general, patients who have decision-making capacity have the right to refuse or discontinue treatment. Example: Jehovah’s Witnesses can refuse blood products. Living will: Addresses a patient’s wishes to maintain, withhold, or withdraw life-sustaining treatment in the event of terminal disease or a persistent vegetative state. Examples include DNR (do not resuscitate) and DNI (do not intubate) orders. Durable power of attorney for health care (DPOAHC): Legally designates a surrogate health care decision maker if a patient lacks decision-making capacity. More ﬂ exible than a living will. Surrogates should make decisions consistent with the person’s stated wishes.


First_Aid_Step2

First_Aid_Step2. If no living will or DPOAHC exists, decisions should be made by close family members (spouse, adult children, parents, and adult siblings), friends, or personal physicians, in that order. In the absence of a living will or DPOA, the Spouse CHIPS in For the Person: Spouse, CHIldren, Parent, Sibling, Friend, Personal physician. DNR/DNI orders do not mean “do not treat.” Patients cannot demand futile treatment from their physicians. A patient’s family cannot require that a doctor withhold information from the patient. Withdrawal of Care Patients and their decision makers have the right to forgo or withdraw life-sustaining treatment. No ethical distinction is considered to exist between withdrawing a treatment that offers no benefit and withholding one that is not indicated. This may include ventilation, ﬂuids, nutrition, and medications such as antibiotics.


First_Aid_Step2

First_Aid_Step2. If the intent is to relieve suffering and medications administered are titrated for that purpose, then it is considered ethical to provide palliative treatment to relieve pain and suffering, even if it may hasten a patient’s death. Example: A physician prescribes midazolam to a patient who is expected to die within a day in order to offer relief from the acute distress of grand mal seizures and pain. Euthanasia is the administration of a lethal agent with the intent to end life. It is opposed by the AMA Code of Medical Ethics and is illegal in all states. Patients who request euthanasia should be evaluated for inadequate pain control and comorbid depression. Physician-assisted suicide is prescribing a lethal agent to a patient who will self-administer it to end his/her own life. This is currently illegal except in the state of Oregon.


First_Aid_Step2

First_Aid_Step2. Physician-assisted suicide is prescribing a lethal agent to a patient who will self-administer it to end his/her own life. This is currently illegal except in the state of Oregon. Physicians are not ethically obligated to provide treatment and may refuse a family member’s request for further intervention on the grounds of futility under the following circumstances: There is no pathophysiologic rationale for treatment. A given intervention has already failed. Maximal intervention is currently failing. Treatment will not achieve the goals of care. Patients have a right to know about their medical status, prognosis, and treatment options (full disclosure). A patient’s family cannot require that a doctor withhold information from the patient.


First_Aid_Step2

First_Aid_Step2. Patients have a right to know about their medical status, prognosis, and treatment options (full disclosure). A patient’s family cannot require that a doctor withhold information from the patient. A doctor may withhold information only if the patient requests not to be told or in the rare case when a physician determines that disclosure would severely harm the patient or undermine their informed decision-making capacity (therapeutic privilege). Physicians are obligated to inform patients of mistakes made in their medical treatment. If the specific error or series of errors is not known, the physician should communicate this with the family promptly and maintain contact with the patient as investigations reveal more facts.


First_Aid_Step2

First_Aid_Step2. If the specific error or series of errors is not known, the physician should communicate this with the family promptly and maintain contact with the patient as investigations reveal more facts. Physicians are obligated to inform patients considering involvement in a clinical research protocol about the purpose of the research study and the entire study design as it will affect the patient’s treatment. This includes the possible risks, benefits, and alternatives to the research protocol. An informed consent form approved by the overseeing research institutional review board (IRB) must be completed for participation in any clinical research protocol, describing the possible risks and benefits of involvement in the research study. Information disclosed by a patient to his/her physician and information about a patient’s medical condition are confidential and cannot be divulged without expressed patient consent.


First_Aid_Step2

First_Aid_Step2. Information disclosed by a patient to his/her physician and information about a patient’s medical condition are confidential and cannot be divulged without expressed patient consent. A patient may waive the right to confidentiality (e.g., with insurance companies). It is ethically and legally necessary to override confidentiality in the following situations: Patient intent to commit a violent crime (Tarasoff decision): Physicians have a duty to protect the intended victim through reasonable means (e.g., warn the victim, notify police). Suicidal patients. Child and elder abuse. Reportable infectious diseases (duty to warn public officials and identifiable people at risk). Gunshot and knife wounds (duty to notify the police). Impaired automobile drivers. Example: A patient begins to drive one week after hospitalization for seizures, although the department of motor vehicles in his state requires that licensed drivers be seizure free for at least three months.


First_Aid_Step2

First_Aid_Step2. Occurs when physicians find themselves having two interests in a given situation and their professional obligations are inﬂuenced by personal interest in another matter. Example: A physician may own stock in a pharmaceutical company (financial interest) that produces a drug he is prescribing to his patient (patient care interest). Physicians should disclose existing conﬂicts of interest to affected parties (e.g., patients, institutions, audiences of journal articles or scientific meetings). The essential elements of a civil suit under negligence include the four D’s: The physician has a Duty to the patient. Dereliction of duty occurs. There is Damage to the patient. Dereliction is the Direct cause of damage. Unlike a criminal suit, in which the burden of proof is “beyond a reasonable doubt,” the burden of proof in a malpractice suit is “a preponderance of the evidence.”


First_Aid_Step2

First_Aid_Step2. Unlike a criminal suit, in which the burden of proof is “beyond a reasonable doubt,” the burden of proof in a malpractice suit is “a preponderance of the evidence.” Disorders of the Stomach and Duodenum 156 GASTRITIS 156 GASTRIC CANCER 157 PEPTIC ULCER DISEASE 157 ZOLLINGER-ELLISON SYNDROME 158 Disorders of the Small Bowel 159 DIARRHEA 159 MALABSORPTION 161 LACTOSE INTOLERANCE 162 CARCINOID SYNDROME 162 IRRITABLE BOWEL SYNDROME 162 SMALL BOWEL OBSTRUCTION 163 ILEUS 164 MESENTERIC ISCHEMIA 165 APPENDICITIS 166 Disorders of the Large Bowel 166 DIVERTICULAR DISEASE 166 LARGE BOWEL OBSTRUCTION 167 COLON AND RECTAL CANCER 167 ISCHEMIC COLITIS 170 Difficulty swallowing (dysphagia) or pain with swallowing (odynophagia) due to abnormalities of the oropharynx or esophagus. Presentation varies according to the location:


First_Aid_Step2

First_Aid_Step2. Difficulty swallowing (dysphagia) or pain with swallowing (odynophagia) due to abnormalities of the oropharynx or esophagus. Presentation varies according to the location: Oropharyngeal dysphagia: Presents with difficulty passing material from the oropharynx to the esophagus. Usually involves liquids more than solids. Causes can be neurologic or muscular and include stroke, Parkinson’s disease, myasthenia gravis, prolonged intubation, and Zenker’s diverticula. Esophageal dysphagia: Usually involves solids more than liquids for most obstructive causes (strictures, Schatzki rings, webs, carcinoma) and is generally progressive. Motility disorders (achalasia, scleroderma, esophageal spasm) present with both liquid and solid dysphagia. Examine for masses (e.g., goiter, tumor) and anatomic defects. Oropharyngeal dysphagia: Cine-esophagram.


First_Aid_Step2

First_Aid_Step2. Examine for masses (e.g., goiter, tumor) and anatomic defects. Oropharyngeal dysphagia: Cine-esophagram. Esophageal dysphagia: Barium swallow followed by endoscopy, manometry, and/or pH monitoring. If an obstructive lesion is suspected, proceed directly to endoscopy with biopsy. Odynophagia: Upper endoscopy. Etiology dependent. Table 2.6-1 outlines the etiology, diagnosis, and treatment of infectious esophagitis. ■A motility disorder in which normal peristalsis is periodically interrupted by high-amplitude nonperistaltic contractions of unknown etiology. Also known as nutcracker esophagus. T AB LE 2.6-1. Causes of Infectious Esophagitis Esophageal webs are associated with iron deficiency anemia and glossitis (Plummer-Vinson syndrome). Candidal esophagitis is an AIDS-defining illness.


First_Aid_Step2

First_Aid_Step2. Esophageal webs are associated with iron deficiency anemia and glossitis (Plummer-Vinson syndrome). Candidal esophagitis is an AIDS-defining illness. Candida albicans Oral thrush Yellow-white plaques adherent to the mucosa. Fluconazole PO HSV Oral ulcers Small, deep ulcerations; multinucleated giant cells with nuclear inclusions on biopsy. Acyclovir IV CMV Retinitis, colitis Large, superfcial ulcerations; intranuclear inclusions on biopsy. Ganciclovir IV The musculature of the upper one-third of the esophagus is skeletal, whereas that of the lower two-thirds is smooth muscle. Malignancy may mimic achalasia (pseudoachalasia). Hx/PE: Presents with chest pain, dysphagia, and odynophagia. Often precipitated by ingestion of hot or cold liquids; relieved by nitroglycerin. Dx: Barium swallow may show a corkscrew-shaped esophagus. Esophageal manometry reveals high-amplitude, simultaneous contractions.


First_Aid_Step2

First_Aid_Step2. Dx: Barium swallow may show a corkscrew-shaped esophagus. Esophageal manometry reveals high-amplitude, simultaneous contractions. Tx: Nitrates and calcium channel blockers (CCBs) for symptomatic relief; surgery (esophageal myotomy) for severe, incapacitating symptoms. A motor disorder of the esophagus characterized by impaired relaxation of the lower esophageal sphincter (LES) and loss of peristalsis in the distal two-thirds of the esophagus. Thought to result from the loss or absence of inhibitory ganglion cells in the myenteric (Auerbach’s) plexus. Hx/PE: Progressive dysphagia, chest pain, regurgitation of undigested food, weight loss, and nocturnal cough are common symptoms. Dx: Barium swallow reveals esophageal dilation with a “bird’s beak” tapering of the distal esophagus (see Figure 2.6-1). Manometry shows ↑ resting LES pressure, incomplete LES relaxation upon swallowing, and ↓ peristalsis in the body of the esophagus.


First_Aid_Step2

First_Aid_Step2. Manometry shows ↑ resting LES pressure, incomplete LES relaxation upon swallowing, and ↓ peristalsis in the body of the esophagus. Mechanical causes of obstruction must be ruled out by endoscopy. Tx: Nitrates, CCBs, or endoscopic injection of botulinum toxin into the LES may provide short-term relief of symptoms. Pneumatic balloon dilation or surgical (Heller) myotomy are definitive treatment options. FIGURE 2.6-1. Achalasia. Barium esophagram reveals esophageal dilation with a “bird’s beak” tapering of the distal esophagus. (Reproduced from Waters PF, DeMeester TR. Foregut motor disorders and their surgical management. Med Clin North Am 65: 1235, © 1981, with permission from Elsevier.) The second most common esophageal motility disorder (after achalasia). Cervical outpouching through the cricopharyngeal muscle is called Zenker’s diverticulum. Diverticula can also occur in the middle and distal third of the esophagus.


First_Aid_Step2

First_Aid_Step2. Cervical outpouching through the cricopharyngeal muscle is called Zenker’s diverticulum. Diverticula can also occur in the middle and distal third of the esophagus. Hx/PE: Patients complain of chest pain, dysphagia, halitosis, and regurgitation of undigested food. Dx: Barium swallow will demonstrate outpouchings. Tx: If symptomatic, treat with surgical excision of the diverticulum. For Zenker’s diverticulum, myotomy of the cricopharyngeus is required to relieve the high-pressure zone. Squamous cell carcinoma (SCC) is the most common type of esophageal cancer worldwide, while adenocarcinoma is most prevalent in the United States, Europe, and Australia. The latter is associated with Barrett’s esophagus (columnar metaplasia of the distal esophagus 2° to chronic GERD). Alcohol use and smoking have been identified as major risk factors for SCC.


First_Aid_Step2

First_Aid_Step2. Alcohol use and smoking have been identified as major risk factors for SCC. Hx/PE: Progressive dysphagia, initially to solids and later to liquids, is common. Weight loss, odynophagia, GERD, GI bleeding, and vomiting are also seen. Dx: Barium study shows narrowing of the esophagus with an irregular border protruding into the lumen. EGD and biopsy confirm the diagnosis. CT and endoscopic ultrasound are used for staging. Tx: Chemoradiation and surgical resection is the definitive treatment, but the prognosis is poor. Surgery is also offered for high-grade Barrett’s dysplasia. Patients who are not candidates for surgery may require an endoscopically placed esophageal stent for palliation and improved quality of life. Symptomatic reﬂux of gastric contents into the esophagus, most commonly as a result of transient LES relaxation. Can be due to an incompetent LES, gastroparesis, or hiatal hernia.


First_Aid_Step2

First_Aid_Step2. Symptomatic reﬂux of gastric contents into the esophagus, most commonly as a result of transient LES relaxation. Can be due to an incompetent LES, gastroparesis, or hiatal hernia. Patients present with heartburn that commonly occurs 30–90 minutes after a meal, worsens with reclining, and often improves with antacids, sitting, or standing. Substernal chest pain can be difficult to distinguish from other causes. Sour taste (“water brash”), globus, unexplained cough, and morning hoarseness can be clues. Exam is usually normal unless a systemic disease (e.g., scleroderma) is present. The history and clinical impression are important. An empiric trial of lifestyle modification and medical treatment is often attempted first. Studies may include barium swallow (to look for hiatal hernia), esophageal manometry, and 24-hour pH monitoring. Squamous cell esophageal cancer is associated with tobacco and alcohol use.


First_Aid_Step2

First_Aid_Step2. Squamous cell esophageal cancer is associated with tobacco and alcohol use. Esophageal cancer metastasizes early because the esophagus lacks a serosa. Risk factors for GERD include hiatal hernia and ↑ intra-abdominal pressure (e.g., obesity, pregnancy). GERD can mimic cough-variant asthma. Patients with GERD should avoid caffeine, alcohol, chocolate, garlic, onions, mints, and nicotine. Type A gastritis is associated with pernicious anemia due to the lack of intrinsic factor necessary for the absorption of vitamin B12. ■ EGD with biopsies should be performed in patients whose symptoms are unresponsive to initial empiric therapy, long-standing (to rule out Barrett’s esophagus and adenocarcinoma), or suggestive of complicated disease (e.g., anorexia, weight loss, dysphagia/odynophagia). Lifestyle: Weight loss, head-of-bed elevation, reduction of meal size, and avoidance of nocturnal meals and substances that ↓ LES tone.


First_Aid_Step2

First_Aid_Step2. Lifestyle: Weight loss, head-of-bed elevation, reduction of meal size, and avoidance of nocturnal meals and substances that ↓ LES tone. Pharmacologic: Start with antacids in patients with mild, intermittent symptoms; use H2 receptor antagonists (cimetidine, ranitidine) or PPIs (omeprazole, lansoprazole) in patients with chronic and frequent symptoms. PPIs are preferred for severe or erosive disease. Surgical: For refractory or severe disease, Nissen fundoplication may offer significant relief. Esophagitis, esophageal stricture, aspiration of gastric contents, upper GI bleeding, Barrett’s esophagus. Herniation of a portion of the stomach upward into the chest through a diaphragmatic opening. There are two common types: Sliding hiatal hernias (95%): The gastroesophageal junction and a portion of the stomach are displaced above the diaphragm.


First_Aid_Step2

First_Aid_Step2. Sliding hiatal hernias (95%): The gastroesophageal junction and a portion of the stomach are displaced above the diaphragm. Paraesophageal hiatal hernias (5%): The gastroesophageal junction remains below the diaphragm, while a neighboring portion of the fundus herniates into the mediastinum. Hx/PE: May be asymptomatic. Those with sliding hernias may present with GERD. Dx: Commonly an incidental finding on CXR; also frequently diagnosed by barium swallow or EGD. Tx: Sliding hernias: Medical therapy and lifestyle modifications to ↓ GERD symptoms. Paraesophageal hernias: Surgical gastropexy (attachment of the stomach to the rectus sheath and closure of the hiatus) is recommended to prevent gastric volvulus. Inﬂammation of the stomach lining. Subtypes are as follows: Acute gastritis: Rapidly developing, superficial lesions that are often due to NSAID use, alcohol, H. pylori infection, and stress from severe illness (e.g., burns, CNS injury).


First_Aid_Step2

First_Aid_Step2. Acute gastritis: Rapidly developing, superficial lesions that are often due to NSAID use, alcohol, H. pylori infection, and stress from severe illness (e.g., burns, CNS injury). Chronic gastritis: ■Type A (10%): Occurs in the fundus and is due to autoantibodies to parietal cells. Causes pernicious anemia and is associated with other autoimmune disorders, such as thyroiditis. Also ↑ the risk of gastric adenocarcinoma. ■Type B (90%): Occurs in the antrum and may be caused by NSAID use or H. pylori infection. Often asymptomatic, but associated with ↑ risk of PUD and gastric cancer. Patients may be asymptomatic or may complain of epigastric pain, nausea, vomiting, hematemesis, or melena. Upper endoscopy can visualize the gastric lining. H. pylori infection can be detected by urease breath test, serum IgG antibodies (which indicate exposure, not current infection), H. pylori stool antigen, or endoscopic biopsy.


First_Aid_Step2

First_Aid_Step2. H. pylori infection can be detected by urease breath test, serum IgG antibodies (which indicate exposure, not current infection), H. pylori stool antigen, or endoscopic biopsy. ■↓ intake of offending agents. Antacids, sucralfate, H2 blockers, and/or PPIs may help. Triple therapy (amoxicillin, clarithromycin, omeprazole) to treat H. pylori infection. Give prophylactic H2 blockers or PPIs to patients at risk for stress ulcers (e.g., ICU patients). This malignant tumor is the second most common cause of cancer-related death worldwide and is particularly common in Korea and Japan. Tumors are generally adenocarcinomas, which exhibit two morphologic types: Intestinal type: Thought to arise from intestinal metaplasia of gastric mucosal cells. Risk factors include a diet high in nitrites and salt and low in fresh vegetables (antioxidants), H. pylori colonization, and chronic gastritis. Diffuse type: Tends to be poorly differentiated and not associated with


First_Aid_Step2

First_Aid_Step2. Diffuse type: Tends to be poorly differentiated and not associated with H. pylori infection or chronic gastritis. Risk factors are largely unknown; signet ring cells are seen on pathology. Hx/PE: Early signs are indigestion and loss of appetite. Advanced cases generally present with abdominal pain, weight loss, or upper GI bleeding. Dx: Early gastric carcinoma is largely asymptomatic and is discovered serendipitously with endoscopic examination of high-risk individuals. Tx: Successful treatment rests entirely on early detection and surgical removal of the tumor. Five-year survival is < 10% for advanced disease. Damage to the gastric or duodenal mucosa caused by impaired mucosal defense and/or ↑ acidic gastric contents. H. pylori plays a causative role in > 90% of duodenal ulcers and 70% of gastric ulcers. Other risk factors include corticosteroid, NSAID, alcohol, and tobacco use. Males are affected more often than females.


First_Aid_Step2

First_Aid_Step2. ■Classically presents with chronic or periodic dull, burning epigastric pain that improves with meals (especially duodenal ulcers), worsens 2–3 hours after eating, and can radiate to the back. Gastric adenocarcinoma that metastasizes to the ovary is called a Krukenberg tumor. Gastric cancer may present with Virchow’s node (an enlarged left supraclavicular lymph node). After a meal, pain from a Gastric ulcer is Greater, whereas Duodenal pain Decreases. Roughly 5–7% of lower GI bleeds are from an upper GI source. Rule out Zollinger-Ellison syndrome with serum gastrin levels in cases of GERD and PUD that are refractory to medical management. Misoprostol can help patients with PUD who require NSAID therapy (e.g., for arthritis). Patients may also complain of nausea, hematemesis (“coffee-ground” emesis), or blood in the stool (melena or hematochezia). Exam may reveal varying degrees of epigastric tenderness and, if there is active bleeding, a stool guaiac.


First_Aid_Step2

First_Aid_Step2. Exam may reveal varying degrees of epigastric tenderness and, if there is active bleeding, a stool guaiac. An acute perforation can present with a rigid abdomen, rebound tenderness, guarding, or other signs of peritoneal irritation. AXR to rule out perforation (free air under the diaphragm); CBC to assess for GI bleeding (low or ↓ hematocrit). Upper endoscopy with biopsy to confirm PUD and to rule out active bleeding or gastric adenocarcinoma (10% of gastric ulcers); barium swallow is an alternative. H. pylori testing. In recurrent or refractory cases, serum gastrin can be used to screen for Zollinger-Ellison syndrome (patients must discontinue PPI use prior to testing). Acute: Rule out active bleeding with serial hematocrits, a rectal exam with stool guaiac, and NG lavage. Monitor the patient’s hematocrit and BP and treat with IV hydration, transfusion, IV PPIs, endoscopy, and surgery as needed for complications. If perforation is likely, emergent surgery is indicated.


First_Aid_Step2

First_Aid_Step2. If perforation is likely, emergent surgery is indicated. Pharmacologic: Involves protecting the mucosa, decreasing acid production, and eradicating H. pylori infection. Treat mild disease with antacids or with sucralfate, bismuth, and misoprostol (a prostaglandin analog) for mucosal protection. PPIs or H2 receptor antagonists may be used to ↓ acid secretion. Patients with confirmed H. pylori infection should receive triple therapy (amoxicillin, clarithromycin, and omeprazole). Discontinue use of exacerbating agents. Patients with recurrent or severe disease may require chronic symptomatic therapy. Endoscopy and surgery: Patients with symptomatic gastric ulcers for > 2 months that are refractory to medical therapy should have either endoscopy or an upper GI series with barium to rule out gastric adenocarcinoma. Refractory cases may require a surgical procedure such as parietal cell vagotomy (the most selective and preferred surgical approach).


First_Aid_Step2

First_Aid_Step2. Refractory cases may require a surgical procedure such as parietal cell vagotomy (the most selective and preferred surgical approach). Hemorrhage (posterior ulcers that erode into the gastroduodenal artery), gastric outlet obstruction, perforation (usually anterior ulcers), intractable pain. ■A rare condition characterized by gastrin-producing tumors in the duodenum and/or pancreas that lead to oversecretion of gastrin. ■↑ gastrin results in the production of high levels of gastric acid by the gastric mucosa, leading to recurrent/intractable ulcers in the stomach and duodenum (may occur more distally). In 20% of cases, gastrinomas are associated with MEN 1 (pancreas, pituitary, and parathyroid tumors). Hx/PE: Patients may present with unresponsive, recurrent gnawing, burning abdominal pain as well as with diarrhea, nausea, vomiting, fatigue, weakness, weight loss, and GI bleeding.


First_Aid_Step2

First_Aid_Step2. Hx/PE: Patients may present with unresponsive, recurrent gnawing, burning abdominal pain as well as with diarrhea, nausea, vomiting, fatigue, weakness, weight loss, and GI bleeding. Dx: ↑ fasting serum gastrin levels are characteristic, as is ↑ gastrin following a secretin stimulation test. Octreotide scan can localize the tumor. Tx: Requires ↓ acid production. H2 blockers are typically ineffective, but a moderateto high-dose PPI often controls symptoms. In light of the malignant potential of the tumor, surgical resection should be attempted where possible. Zollinger-Ellison syndrome is associated with MEN 1 syndrome in roughly 20% of cases. Defined as the production of > 200 g of feces per day along with ↑ frequency or ↓ consistency of stool. Broadly, the four etiologic mechanisms are ↑ motility, ↑ secretion, ↑ luminal osmolarity, and inﬂammation (see also Table 2.6-2). Acute diarrhea: Acute onset with < 2 weeks of symptoms; usually infectious and self-limited.


First_Aid_Step2

First_Aid_Step2. Acute diarrhea: Acute onset with < 2 weeks of symptoms; usually infectious and self-limited. Causes include bacteria with preformed toxins (e.g., S. aureus, Bacillus cereus), noninvasive bacteria (e.g., enterotoxigenic E. coli, Vibrio cholerae, C. difficile), invasive bacteria (e.g., enteroinvasive E. coli, Salmonella, Shigella, Campylobacter, Yersinia), parasites (e.g., Giardia, Entamoeba histolytica), and opportunistic organisms (e.g., Cryptosporidium, Isospora, Microsporidium, CMV). One of the most common causes of pediatric diarrhea is rotavirus infection (most common during winter). Chronic diarrhea: Insidious onset with > 4 weeks of symptoms.


First_Aid_Step2

First_Aid_Step2. One of the most common causes of pediatric diarrhea is rotavirus infection (most common during winter). Chronic diarrhea: Insidious onset with > 4 weeks of symptoms. Can be due to ↑ intestinal secretion (e.g., carcinoid, VIPomas), malabsorption/osmotic diarrhea (e.g., bacterial overgrowth, pancreatic insufficiency, mucosal abnormalities, lactose intolerance), inf ammatory bowel disease (IBD), or altered motility (e.g., IBS). ↑ stool osmotic gap and resolution of diarrhea with fasting suggest osmotic diarrhea. See Figure 2.6-2 for a diagnostic algorithm. Acute diarrhea usually does not require laboratory investigation unless the patient has a high fever, bloody diarrhea, or diarrhea lasting > 4–5 days. Send stool for fecal leukocytes, bacterial culture, C. difficile toxin, and O&P. Consider sigmoidoscopy in patients with bloody diarrhea. Acute diarrhea:


First_Aid_Step2

First_Aid_Step2. Send stool for fecal leukocytes, bacterial culture, C. difficile toxin, and O&P. Consider sigmoidoscopy in patients with bloody diarrhea. Acute diarrhea: When bacterial infection is not suspected, treat with antidiarrheals (e.g., loperamide, bismuth salicylate) and oral rehydration solutions. Acute diarrhea is generally infectious and self-limited. Organisms that cause bloody diarrhea include Salmonella, Shigella, E. coli, and Campylobacter. Diarrhea after ingestion of raw eggs or dairy: think Salmonella. T AB LE 2.6-2. Causes of Infectious Diarrhea


First_Aid_Step2

First_Aid_Step2. Campylobacter The most common etiology of infectious diarrhea. Ingestion of contaminated food or water. Affects young children and young adults. Generally lasts 7–10 days. Fecal RBCs and WBCs. Frequently bloody diarrhea. Rule out appendicitis and IBD. Erythromycin. Clostridium difficile Recent treatment with antibiotics (penicillins, cephalosporins, clindamycin). Affects hospitalized adult patients. Watch for toxic megacolon. Fever, abdominal pain, possible systemic toxicity. Fecal RBCs and WBCs. Most commonly causes colitis, but can involve the small bowel. Identify C. difficile toxin in the stool. Sigmoidoscopy shows pseudomembranes. Cessation of the inciting antibiotic. PO metronidazole or vancomycin; IV metronidazole if the patient cannot tolerate PO. Entamoeba histolytica Ingestion of contaminated food or water; history of travel in developing countries. Incubation period can last up to three months. Severe abdominal pain, fever. Fecal RBCs and WBCs. Chronic amebic colitis mimics


First_Aid_Step2

First_Aid_Step2. contaminated food or water; history of travel in developing countries. Incubation period can last up to three months. Severe abdominal pain, fever. Fecal RBCs and WBCs. Chronic amebic colitis mimics IBD. Steroids can lead to fatal perforation. Treat with metronidazole. E. coli O157:H7 Ingestion of contaminated food (raw meat). Affects children and the elderly. Generally lasts 5–10 days. Severe abdominal pain, low-grade fever, vomiting. Fecal RBCs and WBCs. It is important to rule out GI bleed and ischemic colitis. HUS is a possible complication. Avoid antibiotic or antidiarrheal therapy, which ↑ HUS risk. Ingestion of contaminated poultry or eggs. Affects young children and elderly patients. Generally lasts 2–5 days. Prodromal headache, fever, myalgia, abdominal pain. Fecal WBCs. Sepsis is a concern, as 5–10% of patients become bacteremic. Sickle cell patients are susceptible to invasive disease leading to osteomyelitis. Treat bacteremia or at-risk patients (e.g., sickle cell


First_Aid_Step2

First_Aid_Step2. Sepsis is a concern, as 5–10% of patients become bacteremic. Sickle cell patients are susceptible to invasive disease leading to osteomyelitis. Treat bacteremia or at-risk patients (e.g., sickle cell patients) with oral quinolone or TMP-SMX. Extremely contagious; transmitted between people by the fecal-oral route. Affects young children and institutionalized patients. Fecal RBCs and WBCs. May lead to severe dehydration. Can also cause febrile seizures in the very young. Treat with TMP-SMX to ↓ person-to-person spread. Salmonella Shigella


First_Aid_Step2

First_Aid_Step2. Exclude: 1. Causes of acute diarrhea 2. 3. 4. 5. 6. Fecal leukocytesand occult blood Flexible sigmoidoscopy with biopsy Upper GI series, barium enema HIGH-YIELD FACTS Inflammatory bowel disease Cancer Stool electrolytes, osmolality, weight/24 h, quantitative fat Increased osmotic gap Normal osmotic gap (Reproduced, with permission, from McPhee SJ et al. Current Medical Diagnosis & Treatment, 48th ed. New York: McGraw- Hill, 2009: Fig. 15-2.) If the patient has evidence of systemic infection (e.g., fever, chills, malaise), avoid antimotility agents and consider antibiotics after stool studies have been sent. Chronic diarrhea: Identify the underlying cause and treat symptoms with loperamide, opioids, octreotide, or cholestyramine. Pediatric diarrhea: For children who cannot take medication or PO ﬂ uids—hospitalize, give IV ﬂuids, replete electrolytes, and treat the underlying cause.


First_Aid_Step2

First_Aid_Step2. Pediatric diarrhea: For children who cannot take medication or PO ﬂ uids—hospitalize, give IV ﬂuids, replete electrolytes, and treat the underlying cause. ■Inability to absorb nutrients as a result of an underlying condition such as bile salt def ciency (e.g., bacterial overgrowth, ileal disease), short bowel syndrome, mucosal abnormalities (e.g., celiac disease, Whipple’s disease, tropical sprue), and pancreatic insuff ciency. The small bowel is most commonly involved. Cutaneous ﬂ ushing, diarrhea, wheezing, and cardiac valvular lesions are the most common manifestations of carcinoid tumors. Half of all patients with IBS have comorbid psychiatric disturbances. May result in ↓ absorption of protein, fat, carbohydrates, and micronutrients (folate/B12/iron). Hx/PE: Presents with frequent, loose, watery stools and/or pale, foul-smelling, bulky stools associated with abdominal pain, f atus, bloating, weight loss, nutritional def ciencies, and fatigue.


First_Aid_Step2

First_Aid_Step2. Hx/PE: Presents with frequent, loose, watery stools and/or pale, foul-smelling, bulky stools associated with abdominal pain, f atus, bloating, weight loss, nutritional def ciencies, and fatigue. Tx: Etiology dependent. Institute a gluten-free diet for patients with celiac sprue. Severely affected patients may receive TPN, immunosuppressants, and anti-inﬂ ammatory medications. Results from a defciency of lactase, a brush-border enzyme that hydrolyzes the disaccharide lactose into glucose and galactose. Lactase deficiency is common among populations of African, Asian, and Native American descent. It may also occur transiently 2° to an acute episode of gastroenteritis or other disorders affecting the proximal small intestinal mucosa. Hx/PE: Presents with abdominal bloating, f atulence, cramping, and watery diarrhea following milk ingestion.


First_Aid_Step2

First_Aid_Step2. Hx/PE: Presents with abdominal bloating, f atulence, cramping, and watery diarrhea following milk ingestion. Dx: Hydrogen breath test reveals ↑ breath hydrogen following ingestion of a lactose load (indicates metabolism of lactose by colonic bacteria). An empiric lactose-free diet that results in symptom resolution is highly suggestive of the diagnosis. Tx: Avoidance of dairy products; lactase enzyme replacement. Due to liver metastasis of carcinoid tumors (hormone-producing enterochromaffin cells) that most commonly arise from the ileum and appendix and produce vasoactive substances such as serotonin and substance P. Prior to metastasis, most secreted hormones undergo first-pass metabolism by the liver and do not reach systemic circulation. Hx/PE: Cutaneous fushing, diarrhea, abdominal cramps, wheezing, and right-sided cardiac valvular lesions are the most common manifestations. Symptoms usually follow eating, exertion, or excitement.


First_Aid_Step2

First_Aid_Step2. Hx/PE: Cutaneous fushing, diarrhea, abdominal cramps, wheezing, and right-sided cardiac valvular lesions are the most common manifestations. Symptoms usually follow eating, exertion, or excitement. Dx: High urine levels of the serotonin metabolite 5-HIAA are diagnostic. Octreotide scan can localize the tumor. Tx: Treatment includes octreotide (for symptoms) and debulking of tumor mass. An idiopathic functional disorder that is characterized by changes in bowel habits that ↑ with stress as well as by abdominal pain that is relieved by bowel movements. It is most common in the second and third decades, but since the syndrome is chronic, patients may present at any age. Half of all IBS patients who seek medical care have comorbid psychiatric disorders (e.g., depression, anxiety, fibromyalgia). ■Patients present with abdominal pain, a change in bowel habits (diarrhea and/or constipation), abdominal distention, mucous stools, and relief of pain with a bowel movement.


First_Aid_Step2

First_Aid_Step2. ■Patients present with abdominal pain, a change in bowel habits (diarrhea and/or constipation), abdominal distention, mucous stools, and relief of pain with a bowel movement. IBS rarely awakens patients from sleep; vomiting, significant weight loss, and constitutional symptoms are also uncommon. Exam is usually unremarkable except for mild abdominal tenderness. A diagnosis of exclusion based on clinical history. Tests to rule out other GI causes include CBC, TSH, electrolytes, stool cultures, abdominal films, and barium contrast studies. Manometry can assess sphincter function. Psychological: Patients need reassurance from their physicians. They should not be told that their symptoms are “all in their head.” Dietary: Fiber supplements (psyllium) may help. Pharmacologic: Treat with TCAs, antidiarrheals (loperamide), and antispasmodics (anticholinergics such as dicyclomine).


First_Aid_Step2

First_Aid_Step2. Dietary: Fiber supplements (psyllium) may help. Pharmacologic: Treat with TCAs, antidiarrheals (loperamide), and antispasmodics (anticholinergics such as dicyclomine). Defined as blocked passage of bowel contents through the small bowel. Fluid and gas can build up proximal to the obstruction, leading to ﬂuid and electrolyte imbalances and significant abdominal discomfort. The obstruction can be complete or partial, and ischemia or necrosis of the bowel may occur. SBO may arise from adhesions from a prior abdominal surgery (60% of cases), hernias (10–20%), neoplasms (10–20%), intussusception, gallstone ileus, stricture due to IBD, or volvulus. Patients typically experience cramping abdominal pain with a recurrent crescendo-decrescendo pattern at 5to 10-minute intervals. Vomiting typically follows the pain; early emesis is bilious and nonfeculent if the obstruction is proximal but feculent if it is distal.


First_Aid_Step2

First_Aid_Step2. Vomiting typically follows the pain; early emesis is bilious and nonfeculent if the obstruction is proximal but feculent if it is distal. In partial obstruction, there is continued passage of ﬂatus but no stool, whereas in complete obstruction, no ﬂatus or stool is passed (obstipation). Abdominal exam often reveals distention, tenderness, prior surgical scars, or hernias. Bowel sounds are characterized by high-pitched tinkles and peristaltic rushes. Peristalsis may disappear later in disease progression. Fever, hypotension, rebound tenderness, and tachycardia suggest peritonitis, a surgical emergency. CBC may demonstrate leukocytosis if there is ischemia or necrosis of bowel. Labs often reﬂ ect dehydration and metabolic alkalosis due to vomiting. Lactic acidosis is particularly worrisome, as it suggests necrotic bowel and the need for emergent surgical intervention.


First_Aid_Step2

First_Aid_Step2. Labs often reﬂ ect dehydration and metabolic alkalosis due to vomiting. Lactic acidosis is particularly worrisome, as it suggests necrotic bowel and the need for emergent surgical intervention. Abdominal films often demonstrate a stepladder pattern of dilated small-bowel loops, air-f uid levels (see Figure 2.6-3), and a paucity of gas in the colon. The presence of radiopaque material at the cecum is suggestive of gallstone ileus. IBS is a diagnosis of exclusion. The leading cause of SBO in children is hernias. The leading cause of SBO in adults is adhesions. Never let the sun rise or set on a complete SBO. Anticholinergics, opioids, and hypokalemia slow GI motility. F IGU R E 2.6-3. Acute mechanical obstruction of the small intestine (upright film). Note the air-ﬂuid levels, marked distention of bowel loops, and absence of colonic gas. (Repro duced, with permission, from Kasper DL et al. Harrison’s Principles of Internal Medicine, 16th ed. New York: McGraw-Hill, 2005: 1804.)


First_Aid_Step2

First_Aid_Step2. For partial obstruction, supportive care may be sufficient and should include NPO status, NG suction, IV hydration, correction of electrolyte abnormalities, and Foley catheterization to monitor ﬂ uid status. Surgery is required in cases of complete SBO, vascular compromise (necrotic bowel), or symptoms lasting > 3 days without resolution. Exploratory laparotomy may be performed with lysis of adhesions, resection of necrotic bowel, and evaluation for stricture, IBD, and hernias. There is a 2% mortality risk for a nonstrangulated SBO; strangulated SBO is associated with up to a 25% mortality rate depending on the time between diagnosis and treatment. A second-look laparotomy or laparoscopy may be performed 18–36 hours after initial surgical treatment to reevaluate bowel viability if ischemia is a concern.


First_Aid_Step2

First_Aid_Step2. A second-look laparotomy or laparoscopy may be performed 18–36 hours after initial surgical treatment to reevaluate bowel viability if ischemia is a concern. Loss of peristalsis without structural obstruction. Risk factors include recent surgery/GI procedures, severe medical illness, immobility, hypokalemia or other electrolyte imbalances, hypothyroidism, DM, and medications that slow GI motility (e.g., anticholinergics, opioids). Presenting symptoms include diffuse, constant, moderate abdominal discomfort; nausea and vomiting (especially with eating); and an absence of fatulence or bowel movements. Exam may reveal diffuse tenderness and abdominal distention, no peritoneal signs, and ↓ or absent bowel sounds. A rectal exam is required to rule out fecal impaction in elderly patients. Diffusely distended loops of small and large bowel are seen on supine AXR with air-ﬂuid levels on upright view.


First_Aid_Step2

First_Aid_Step2. A rectal exam is required to rule out fecal impaction in elderly patients. Diffusely distended loops of small and large bowel are seen on supine AXR with air-ﬂuid levels on upright view. A Gastrografin study can rule out partial obstruction; CT can rule out neo-In diagnosing ileus, look for plasms. air throughout the small and large bowel on AXR. ■↓ or discontinue the use of narcotics and any other drugs that reduce bowel motility. Temporarily ↓ or discontinue oral feeds. Initiate NG suction/parenteral feeds as necessary. Replete electrolytes as needed. ↓ mesenteric blood supply leading to insufficient perfusion to intestinal tissue and ischemic injury. Causes include acute arterial occlusion (usually involving the SMA) from thrombosis (due to atherosclerosis) or embolism (due to atrial fibrillation or ↓ ejection fraction); nonocclusive arterial disease (low cardiac output, arteriolar vasospasm); and venous thrombosis (due to hypercoagulable states).


First_Aid_Step2

First_Aid_Step2. Patients present with sudden onset of severe abdominal pain out of proportion to the exam. A history of prior episodes of similar abdominal pain after eating (“intestinal angina”) may be present. Other symptoms may include nausea, vomiting, diarrhea, and bloody stools. Early abdominal exam is often unremarkable; later findings may include peritoneal signs (suggest bowel infarction). Lab tests may show leukocytosis, metabolic acidosis with ↑ lactate, ↑ amylase, ↑ LDH, and ↑ CK. AXR and CT may reveal bowel wall edema (“thumbprinting”) and air within the bowel wall (pneumatosis intestinalis). Mesenteric angiography is the gold standard for arterial occlusive disease. Volume resuscitation, broad-spectrum antibiotics, optimization of hemodynamics, and avoidance of vasoconstrictors. Anticoagulation for arterial or venous thrombosis or embolism. The mortality rate for acute mesenteric ischemia is > 50%.


First_Aid_Step2

First_Aid_Step2. Anticoagulation for arterial or venous thrombosis or embolism. The mortality rate for acute mesenteric ischemia is > 50%. Diverticulosis is the most common cause of acute lower GI bleeding in patients > 40 years of age. Diverticular disease must be distinguished from colon cancer with perforation. Avoid ﬂ exible sigmoidoscopy and barium enemas in the initial stages of diverticulitis because of perforation risk. Early laparotomy for acute arterial occlusive disease or if evidence of peritonitis or clinical deterioration is present. Angioplasty and thrombectomy +/– endovascular stenting for acute arterial thrombosis. Embolectomy for acute arterial embolism. Resection of infarcted bowel. Sepsis/septic shock, multisystem organ failure, death. See the Emergency Medicine chapter.


First_Aid_Step2

First_Aid_Step2. Embolectomy for acute arterial embolism. Resection of infarcted bowel. Sepsis/septic shock, multisystem organ failure, death. See the Emergency Medicine chapter. Outpouchings of mucosa and submucosa (false diverticula) that herniate through the colonic muscle layers in areas of high intraluminal pressure; most commonly found in the sigmoid colon. Diverticulosis is the most common cause of acute lower GI bleeding in patients > 40 years of age. Risk factors include a low-fber and high-fat diet, advanced age (65% occur in those > 80 years of age), and connective tissue disorders (e.g., Ehlers-Danlos syndrome). Diverticulitis is due to inﬂammation and, potentially, perforation of a diverticulum 2° to fecalith impaction. Diverticulosis is often asymptomatic. Bleeding is painless and sudden, generally presenting as hematochezia with symptoms of anemia (fatigue, lightheadedness, dyspnea on exertion).


First_Aid_Step2

First_Aid_Step2. Diverticulosis is often asymptomatic. Bleeding is painless and sudden, generally presenting as hematochezia with symptoms of anemia (fatigue, lightheadedness, dyspnea on exertion). Diverticulitis presents with LLQ abdominal pain, fever, nausea, vomiting, and constipation. Perforation is a serious complication that leads to peritonitis and shock. CBC may show leukocytosis. Diagnosis is based on AXR (to rule out free air, ileus, or obstruction), colonoscopy, or barium enema. Sigmoidoscopy/colonoscopy must be avoided in those with early diverticulitis due to the risk of perforation. In patients with severe disease or in those who show lack of improvement, abdominal CT may reveal abscess or free air. Uncomplicated diverticulosis: Patients can be followed and placed on a high-f ber diet or fiber supplements. Diverticular bleeding: Bleeding usually stops spontaneously; transfuse and hydrate as needed. If bleeding does not stop, angiography with embolization or surgery is indicated.


First_Aid_Step2

First_Aid_Step2. Diverticular bleeding: Bleeding usually stops spontaneously; transfuse and hydrate as needed. If bleeding does not stop, angiography with embolization or surgery is indicated. Diverticulitis: Treat with bowel rest (NPO), NG tube placement, and broad-spectrum antibiotics (metronidazole and a ﬂuoroquinolone or a secondor third-generation cephalosporin) if the patient is stable. Avoid barium enema and ﬂexible sigmoidoscopy if diverticulitis is suspected. ■For perforation, perform immediate surgical resection of diseased bowel via a Hartmann’s procedure with a temporary colostomy. Table 2.6-3 describes features that distinguish SBO from LBO. Figure 2.6-4 demonstrates the classic radiographic findings of LBO. The second leading cause of cancer mortality in the United States after lung cancer. There is an ↑ incidence with age, with a peak incidence at 70– 80 years. There has also been an observed association between colon cancer


First_Aid_Step2

First_Aid_Step2. T AB LE 2.6-3. Characteristics of Small and Large Bowel Obstruction


First_Aid_Step2

First_Aid_Step2. History Moderate to severe acute abdominal pain; copious emesis. Cramping pain with distal SBO. Fever, signs of dehydration, and hypotension may be seen. Constipation/obstipation, deep and cramping abdominal pain (less intense than SBO), nausea/ vomiting (less than SBO but more commonly feculent). PE Abdominal distention (distal SBO), abdominal tenderness, visible peristaltic waves, fever, hypovolemia. Look for surgical scars/hernias; perform a rectal exam. High-pitched “tinkly” bowel sounds; later, absence of bowel sounds. Signif cant distention, tympany, and tenderness; examine for peritoneal irritation or mass; fever or signs of shock suggest perforation/peritonitis or ischemia/necrosis. High-pitched “tinkly” bowel sounds; later, absence of bowel sounds. Etiologies Adhesions (postsurgery), hernias, neoplasm, volvulus, intussusception, gallstone ileus, foreign body, Crohn’s disease, CF, stricture, hematoma. Colon cancer, diverticulitis, volvulus, fecal impaction, benign tumors.


First_Aid_Step2

First_Aid_Step2. hernias, neoplasm, volvulus, intussusception, gallstone ileus, foreign body, Crohn’s disease, CF, stricture, hematoma. Colon cancer, diverticulitis, volvulus, fecal impaction, benign tumors. Assume colon cancer until proven otherwise. Differential LBO, paralytic ileus, gastroenteritis. SBO, paralytic ileus, appendicitis, IBD, Ogilvie’s syndrome (pseudo-obstruction). CBC, electrolytes, lactic acid, AXR (see Figure 2.6-3); contrast studies (determine if it is partial or complete), CT scan. CBC, electrolytes, lactic acid, AXR (see Figure 2.6-4), CT scan; water contrast enema (if perforation is suspected); sigmoidoscopy/colonoscopy if stable.


First_Aid_Step2

First_Aid_Step2. Hospitalize. Partial SBO can be treated conservatively with NG decompression and NPO status. Patients with complete SBO should be managed aggressively with NPO status, NG decompression, IV fuids, electrolyte replacement, and surgical correction. Hospitalize. Obstruction can be relieved with a Gastrografn enema, colonoscopy, or a rectal tube; however, surgery is usually required. Ischemic colon usually requires partial colectomy with a diverting colostomy. Treat the underlying cause (e.g., neoplasm). TABLE 2.6-4. FIGURE 2.6-4. Large bowel obstruction. Barium study shows the “bird-beak” sign, with juxtaposed adjacent bowel walls in the dilated loop pointing toward the site of obstruction. (Reproduced, with permission, from Way LW. Current Surgical Diagnosis & Treatment, 10th ed. Stamford, CT: Appleton & Lange, 1994: 676.) and Streptococcus bovis bacteremia. Risk factors and screening protocols are summarized in Table 2.6-4.


First_Aid_Step2

First_Aid_Step2. ■In the absence of screening, colon and rectal cancer typically present with symptoms only after a prolonged period of silent growth. Age. Hereditary syndromes—familial adenomatous polyposis (100% risk by age 40), Gardner’s disease, hereditary nonpolyposis colorectal cancer (HNPCC). Family history. IBD—ulcerative colitis carries a higher risk than does Crohn’s disease. Adenomatous polyps—villous polyps progress more often than tubular polyps and sessile more than pedunculated polyps. Lesions > 2 cm carry an ↑ risk. Past history of colorectal cancer. High-fat, low-f ber diet. A DRE should be performed yearly for patients ≥ 50 years of age. Up to 10% of all lesions are palpable with DRE. Stool guaiac should be performed every year for patients ≥ 50 years of age. Up to 50% of guaiac tests are due to colorectal cancer. Colonoscopy every 10 years in those ≥ 50 years of age OR yearly FOBT with sigmoidoscopy every 5 years.


First_Aid_Step2

First_Aid_Step2. Colonoscopy every 10 years in those ≥ 50 years of age OR yearly FOBT with sigmoidoscopy every 5 years. Colonoscopy should be performed every 10 years in patients ≥ 40 years of age who have a frst-degree relative with colorectal cancer or adenomatous polyps, or 10 years prior to the age at diagnosis of the youngest family member. Although often asymptomatic, patients may present with unexplained anemia or vague abdominal pain. Other features depend on location: Right-sided lesions: Often bulky, ulcerating masses that lead to anemia from chronic occult blood loss. Patients may complain of weight loss, anorexia, diarrhea, weakness, or vague abdominal pain. Obstruction is rare. Left-sided lesions: Typically “apple-core” obstructing masses (see Figure 2.6-5). Patients complain of a change in bowel habits (e.g., ↓ stool caliber, constipation, obstipation), colicky abdominal pain, and/or blood-streaked stools. Obstruction is common.


First_Aid_Step2

First_Aid_Step2. Rectal lesions: Usually present with bright red blood per rectum, often with tenesmus and/or rectal pain. Can coexist with hemorrhoids, so rectal cancer must be ruled out in all patients with rectal bleeding. Order a CBC (often shows microcytic anemia) and stool occult blood. Perform sigmoidoscopy to evaluate rectal bleeding and all suspicious left-sided lesions. Rule out synchronous right-sided lesions with colonoscopy. If colonoscopy is incomplete, rule out additional lesions with an air-contrast barium enema. Determine the degree of invasion in rectal cancer with endorectal ultrasound. Order a CXR, LFTs, and an abdominal/pelvic CT for metastatic workup. Metastases may arise from direct extension to local viscera, hematogenous spread (40–50% go to the liver, but spread may also occur to bone, lungs, and brain), or lymphatic spread (to pelvic lymph nodes). Iron deficiency anemia in an elderly male is colorectal cancer until proven otherwise. FIGURE 2.6-5. Colon carcinoma.


First_Aid_Step2

First_Aid_Step2. Iron deficiency anemia in an elderly male is colorectal cancer until proven otherwise. FIGURE 2.6-5. Colon carcinoma. The encircling carcinoma appears as an “apple-core” filling defect in the descending colon on barium enema x-ray. (Reproduced, with permission, from Way LW. Current Surgical Diagnosis & Treatment, 10th ed. Stamford, CT: Appleton & Lange, 1994: 658.) ■Staging is based on the depth of tumor penetration into the bowel wall and the presence of lymph node involvement and distant metastases. Ischemic colitis is a known complication of AAA repair due to sacrifice of the inferior mesenteric artery. One unit of PRBCs should ↑ hemoglobin by 1 unit and hematocrit by 3–4 units. Surgical resection of the 1° cancer is the treatment of choice. Regional lymph node dissection should be performed for staging purposes. For rectal lesions, the resection technique depends on the proximity of the lesion to the anal verge (the junction between the anal canal and the anal skin).


First_Aid_Step2

First_Aid_Step2. For rectal lesions, the resection technique depends on the proximity of the lesion to the anal verge (the junction between the anal canal and the anal skin). Abdominoperineal resection: For distal lesions < 10 cm from the anal verge, when the sphincter cannot be preserved, the rectum and anus are resected and a permanent colostomy is placed. Low anterior resection: For proximal lesions > 10 cm from the anal verge, a 1° anastomosis is created between the colon and rectum. Wide local excision: For small, low-grade, well-differentiated tumors in the lower third of the rectum. Adjuvant chemotherapy: Used in cases of colon cancer with lymph nodes. Can be considered for rectal cancers. Follow with serial CEA levels (diagnostically nonspecific, but useful for monitoring recurrence), colonoscopy, LFTs, CXR, and abdominal CT (for metastasis). Due to lack of arterial blood supply to the colon. Severity ranges from superficial mucosal involvement to full-thickness necrosis.


First_Aid_Step2

First_Aid_Step2. Due to lack of arterial blood supply to the colon. Severity ranges from superficial mucosal involvement to full-thickness necrosis. The most commonly affected site is the left colon, particularly the “watershed area” at the splenic ﬂ exure. Incidence ↑ with age. Hx/PE: Presents with crampy lower abdominal pain associated with bloody diarrhea. Fever and peritoneal signs suggest infarction. Dx: CBC may reveal leukocytosis. Flexible sigmoidoscopy or colonoscopy to assess colonic mucosa. Tx: Supportive therapy with bowel rest, IV ﬂuids, and broad-spectrum antibiotics. Surgery with resection is indicated for infarction, fulminant colitis, or obstruction 2° to ischemic stricture. Bleeding from the GI tract may present as hematemesis, hematochezia, and/or melena. Upper GI tract bleeding is defined as bleeding from lesions proximal to the ligament of Treitz (the anatomic boundary between the duodenum and jejunum). Table 2.6-5 presents the features of upper and lower GI bleeding.


First_Aid_Step2

First_Aid_Step2. Comprises Crohn’s disease and ulcerative colitis (see Figure 2.6-6). Most common in Caucasians and Ashkenazi Jews, appearing most frequently during the teens to early 30s or in the 50s. Table 2.6-6 summarizes the features of IBD. T AB LE 2.6-5. Features of Upper and Lower GI Bleeding


First_Aid_Step2

First_Aid_Step2. HIGH-YIELD FACTS History/PE Hematemesis (”coffee-ground” emesis), melena > hematochezia, depleted volume status (e.g., tachycardia, lightheadedness, hypotension). Hematochezia > melena, but can be either. Diagnosis NG tube and NG lavage; endoscopy if stable. Rule out upper GI bleed with NG lavage. Anoscopy/sigmoidoscopy for patients < 45 years of age with small-volume bleeding. Colonoscopy if stable; arteriography or exploratory laparotomy if unstable. Etiologies PUD, esophagitis/gastritis, Mallory-Weiss tear, esophageal varices. Diverticulosis (60%), IBD, hemorrhoids/f ssures, neoplasm, AVM. Initial management Protect the airway (may need intubation). Stabilize the patient with IV fuids and PRBCs (hematocrit may be normal early in acute blood loss). Similar to upper GI bleed. Long-term management Endoscopy followed by therapy directed at the underlying cause (e.g., high-dose PPIs for PUD; octreotide and/or banding for varices). Depends on the underlying etiology. Endoscopic therapy


First_Aid_Step2

First_Aid_Step2. management Endoscopy followed by therapy directed at the underlying cause (e.g., high-dose PPIs for PUD; octreotide and/or banding for varices). Depends on the underlying etiology. Endoscopic therapy (e.g., epinephrine injection), intra-arterial vasopressin infusion or embolization, or surgery for diverticular disease or angiodysplasia.


First_Aid_Step2

First_Aid_Step2. F IGU R E 2.6-6. Inﬂammatory bowel disease. (A) Crohn’s disease. Barium enema x-ray reveals deep transverse fissures, ulcers, and edema of the bowel. (B) Ulcerative colitis. Barium enema x-ray demonstrates shortening of the colon, loss of haustra (“lead pipe” appearance), and fine serrations of the bowel edges from small ulcers. (Reproduced, with permission, from Stobo J et al. The Principles and Practice of Medicine, 23rd ed. Stamford, CT: Appleton & Lange, 1996: 135.) T AB LE 2.6-6. Features of Ulcerative Colitis and Crohn’s Disease


First_Aid_Step2

First_Aid_Step2. Site of involvement The rectum is always involved. May extend proximally in a continuous fashion. Infammation and ulceration are limited to the mucosa and submucosa. May involve any portion of the GI tract, particularly the ileocecal region, in a discontinuous pattern (“skip lesions”). The rectum is often spared. Transmural inﬂ ammation is seen. History/PE Bloody diarrhea, lower abdominal cramps, tenesmus, urgency. Exam may reveal orthostatic hypotension, tachycardia, abdominal tenderness, frank blood on rectal exam, and extraintestinal manifestations. Abdominal pain, abdominal mass, low-grade fever, weight loss, watery diarrhea. Exam may reveal fever, abdominal tenderness or mass, perianal fissures, fistulas, and extraintestinal manifestations. Extraintestinal manifestations Aphthous stomatitis, episcleritis/uveitis, arthritis, primary sclerosing cholangitis, erythema nodosum, and pyoderma gangrenosum. The same as ulcerative colitis, as well as gallstones, nephrolithiasis, and


First_Aid_Step2

First_Aid_Step2. stomatitis, episcleritis/uveitis, arthritis, primary sclerosing cholangitis, erythema nodosum, and pyoderma gangrenosum. The same as ulcerative colitis, as well as gallstones, nephrolithiasis, and fstulas to the skin, bladder, or between bowel loops. Diagnosis CBC, AXR, stool cultures, O&P, stool assay for The same lab workup as ulcerative colitis. Upper GI


First_Aid_Step2

First_Aid_Step2. C. difficile. Colonoscopy can show diffuse and continuous rectal involvement, friability, edema, and pseudopolyps. Defnitive diagnosis can be made with biopsy. 5-ASA agents (e.g., sulfasalazine, mesalamine), topical or oral; corticosteroids and immunomodulating agents (e.g., azathioprine) for refractory disease. Total proctocolectomy is curative for longstanding or fulminant colitis or toxic megacolon; it also ↓ cancer risk. Markedly ↑ risk of colorectal cancer in longstanding cases (monitor with frequent fecal occult blood screening and yearly colonoscopy with multiple biopsies after eight years of disease). series with small bowel follow-through. Colonoscopy may show aphthoid, linear, or stellate ulcers, strictures, “cobblestoning,” and “skip lesions.” “Creeping fat” may also be present during laparotomy. Defnitive diagnosis can be made with biopsy.


First_Aid_Step2

First_Aid_Step2. Defnitive diagnosis can be made with biopsy. 5-ASA agents; corticosteroids and immunomodulating agents (e.g., azathioprine, infiximab) are indicated if no improvement is seen. Surgical resection may be necessary for suspected perforation, stricture, fstula, or abscess; may recur anywhere in the GI tract. Incidence of 2° malignancy is lower than in ulcerative colitis, but greater than the general population. Abnormal protrusions of abdominal contents (usually the small intestine) into the inguinal region through a weakness or defect in the abdominal wall. Defined as direct or indirect on the basis of their relationship to the inguinal canal. ■ Indirect: Herniation of abdominal contents through the internal and then external inguinal rings and eventually into the scrotum (in males). The most common hernia in both genders. Due to a congenital patent processus vaginalis. Protrudes lateral to the inferior epigastric vessels.


First_Aid_Step2

First_Aid_Step2. The most common hernia in both genders. Due to a congenital patent processus vaginalis. Protrudes lateral to the inferior epigastric vessels. Direct: Herniation of abdominal contents through the ﬂ oor of Hesselbach’s triangle. Protrudes medial to the epigastric vessels. Hernial sac contents do not traverse the internal inguinal ring; they herniate directly through the abdominal wall and are contained within the aponeurosis of the external oblique muscle. Most often due to an acquired defect in the transversalis fascia from mechanical breakdown that ↑ with age. Because of the risk of incarceration and strangulation, surgical management (open or laparoscopic) is indicated unless specific contraindications are present. Repair of a direct inguinal hernia involves correcting the defect in the transversalis fascia.


First_Aid_Step2

First_Aid_Step2. Repair of a direct inguinal hernia involves correcting the defect in the transversalis fascia. Indirect inguinal hernias are repaired by isolating and ligating the hernial sac and reducing the size of the internal inguinal ring to allow only the spermatic cord structures in males to pass through. Hesselbach’s triangle is an area bounded by the inguinal ligament, the inferior epigastric artery, and the rectus abdominis. Colic results from transient cystic duct blockage from impacted stones. Although risk factors include the 4 F’s—Female, Fat, Fertile, and Forty—the disorder is common and can occur in any patient. Flatulence can be thought of as a “5th F.” Other risk factors include OCP use, rapid weight loss, a family history, chronic hemolysis (pigment stones in sickle cell disease), small bowel resection, and TPN. Patients present with postprandial abdominal pain (usually in the RUQ) that radiates to the right subscapular area or the epigastrium.


First_Aid_Step2

First_Aid_Step2. Patients present with postprandial abdominal pain (usually in the RUQ) that radiates to the right subscapular area or the epigastrium. Pain is abrupt; is followed by gradual relief; and is often associated with nausea and vomiting, fatty food intolerance, dyspepsia, and ﬂ atulence. Gallstones may be asymptomatic in up to 80% of patients. Exam may reveal RUQ tenderness and a palpable gallbladder. Plain x-rays are rarely diagnostic; only 10–15% of stones are radiopaque. RUQ ultrasound is the imaging modality of choice (85–90% sensitive). Table 2.6-7 contrasts lab findings with those of other forms of biliary disease. Cholecystectomy is curative and can be performed electively for symptomatic gallstones. It is generally performed laparoscopically. Asymptomatic gallstones do not require any intervention. Patients may require preoperative endoscopic retrograde cholangiopancreatography (ERCP) for common bile duct stones.


First_Aid_Step2

First_Aid_Step2. Patients may require preoperative endoscopic retrograde cholangiopancreatography (ERCP) for common bile duct stones. Treat nonsurgical candidates with dietary modif cation (avoid triggers such as fatty foods). Pigmented gallstones result from hemolysis (black) or infection (brown). Most gallstones are precipitations of cholesterol and are not radiopaque. TAB LE 2.6-7. Differential Diagnosis of Biliary Disease The cystic artery usually passes through the anatomic triangle of Calot, comprising the common hepatic duct, the cystic duct, and the inferior border of the liver. In patients with significant medical problems (including DM), delay cholecystectomy until acute inﬂ ammation resolves. Recurrent biliary colic, acute cholecystitis, choledocholithiasis, ascending cholangitis, gallstone ileus, gallstone pancreatitis.


First_Aid_Step2

First_Aid_Step2. Recurrent biliary colic, acute cholecystitis, choledocholithiasis, ascending cholangitis, gallstone ileus, gallstone pancreatitis. Prolonged blockage of the cystic duct, usually by an impacted stone, that leads to obstructive distention, inﬂammation, superinfection, and possibly gangrene of the gallbladder (acute gangrenous cholecystitis). Acalculous cholecystitis occurs in the absence of cholelithiasis in patients who are chronically debilitated, those who are critically ill in the ICU or on TPN, and trauma or burn victims. Patients present with RUQ pain, nausea, vomiting, and fever. Symptoms are typically more severe and of longer duration than those of biliary colic. RUQ tenderness, inspiratory arrest during deep palpation of the RUQ (Murphy’s sign), low-grade fever, mild icterus, and possibly guarding or rebound tenderness may be present on exam. Fever is often present, and CBC shows leukocytosis (see Table 2.6-7).


First_Aid_Step2

First_Aid_Step2. Fever is often present, and CBC shows leukocytosis (see Table 2.6-7). Ultrasound may demonstrate stones, bile sludge, pericholecystic ﬂ uid, a thickened gallbladder wall, gas in the gallbladder, and an ultrasonic Murphy’s sign (see Figure 2.6-7). Obtain a HIDA scan when ultrasound is equivocal (see Figure 2.6-8); nonvisualization of the gallbladder on HIDA scan suggests acute cholecystitis. Hospitalize patients, administer broad-spectrum IV antibiotics and IV f u-ids, and replete electrolytes. If diagnosed soon after onset, early cholecystectomy is indicated. For stable patients or those with significant medical problems, surgery can be delayed for 4–6 weeks. F IGU R E 2.6-7. Acute cholecystitis, ultrasound. Note the sludge-filled, thick-walled gallbladder with a hyperechoic stone and acoustic shadow (arrow). (B) This patient exhibits sludge and pericholecystic ﬂuid (arrow) but no gallstones. (Reproduced, with permission, from Grendell J.


First_Aid_Step2

First_Aid_Step2. J. Current Diagnosis & Treatment in Gastroenterology, 1st ed. Stamford, CT: Appleton & Lange, 1996: 212.) Gangrene, empyema, perforation, emphysematous gallbladder (due to infection by gas-forming organisms), fistulization, gallstone ileus, sepsis, abscess formation. ■Gallstones in the common bile duct. Symptoms vary according to the degree of obstruction, the duration of the obstruction, and the extent of bacterial infection. F IGU R E 2.6-8. Acute cholecystitis, HIDA scan. IV dye is taken up by hepatocytes and is conjugated and excreted into the common bile duct. The gallbladder is not visualized, although activity is present in the liver, common duct, and small bowel, suggesting cystic duct obstruction due to acute cholecystitis. (Reproduced, with permission, from Grendell J. Current Diagnosis & Treatment in Gastroenterology, 1st ed. Stamford, CT: Appleton & Lange, 1996: 217.) Gallstone pancreatitis occurs when stones in the ampulla also obstruct the pancreatic duct.


First_Aid_Step2

First_Aid_Step2. Gallstone pancreatitis occurs when stones in the ampulla also obstruct the pancreatic duct. Charcot’s triad consists of RUQ pain, jaundice, and fever/chills. Reynolds’ pentad consists of RUQ pain, jaundice, fever/chills, shock, and altered mental status. Hx/PE: Although sometimes asymptomatic, it often presents with biliary colic, jaundice, fever, and pancreatitis. Dx: The hallmark is ↑ alkaline phosphatase and total bilirubin, which may be the only abnormal lab values (see Table 2.6-7). Tx: Management generally consists of ERCP with sphincterotomy followed by semielective cholecystectomy. Common bile duct exploration may be necessary.


First_Aid_Step2

First_Aid_Step2. Tx: Management generally consists of ERCP with sphincterotomy followed by semielective cholecystectomy. Common bile duct exploration may be necessary. An acute bacterial infection of the biliary tree that commonly occurs 2° to obstruction, usually from gallstones (choledocholithiasis) or primary sclerosing cholangitis (progressive inﬂammation of the biliary tree associated with ulcerative colitis). Other etiologies include bile duct stricture and malignancy (biliary or pancreatic). Gram-enterics (e.g., E. coli, Enterobacter, Pseudomonas) are commonly identified pathogens. Charcot’s triad—RUQ pain, jaundice, and fever/chills—is classic and seen in 50–70% of cases. Reynolds’ pentad—Charcot’s triad plus septic shock and altered mental status—may be present in acute suppurative cholangitis and suggests sepsis. Look for leukocytosis, ↑ bilirubin, and ↑ alkaline phosphatase (see Table 2.6-7).


First_Aid_Step2

First_Aid_Step2. Look for leukocytosis, ↑ bilirubin, and ↑ alkaline phosphatase (see Table 2.6-7). Obtain blood cultures to rule out sepsis. Ultrasound or CT may be a useful adjunct, but diagnosis is often clinical. Magnetic resonance cholangiopancreatography (MRCP) is a noninvasive test that may also be useful. ERCP is both diagnostic and therapeutic (biliary drainage). Patients often require ICU admission for monitoring, hydration, BP support, and broad-spectrum IV antibiotic treatment. Patients with acute suppurative cholangitis require emergent bile duct decompression via ERCP/sphincterotomy, percutaneous transhepatic drainage, or open decompression. A mechanical obstruction resulting from the passage of a large (> 2.5-cm) stone into the bowel through a cholecystoduodenal fistula. Obstruction is often at the terminal ileum (TI)/ileocecal valve.


First_Aid_Step2

First_Aid_Step2. A mechanical obstruction resulting from the passage of a large (> 2.5-cm) stone into the bowel through a cholecystoduodenal fistula. Obstruction is often at the terminal ileum (TI)/ileocecal valve. Hx/PE: Many patients have no previous history of biliary symptoms and present as an SBO. The classic presentation is that of a subacute SBO in an elderly woman. Dx: Pneumobilia (gas in the biliary tree) seen on imaging can confirm, in addition to an upper GI series with small bowel follow-through showing a TI obstruction. Tx: Laparotomy with stone extraction (enterolithotomy) or manipulation into the colon. ■An idiopathic disorder characterized by inﬂ ammation, fibrosis, and strictures of extraand intrahepatic bile ducts. The disease usually presents in young men with IBD (most often ulcerative colitis). Hx/PE: Presents with progressive jaundice, pruritus, and fatigue. Dx: is significantly associated with ■ Laboratory findings include ↑ alkaline phosphatase and ↑ bilirubin.