gastrointestinal disorders
Constipation
Evaluation of Constipation
History of present illnessshould ascertain a lifetime history of the patient’s stool frequency, consistency, need to strain or use perineal maneuvers (eg, pushing on the perineum, gluteal region, or recto-vaginal wall) during defecation, and satisfaction after defecation should be obtained, including frequency and duration of laxative or enema use. Some patients deny previous constipation but, when questioned specifically, admit to spending 15 to 20 minutes per bowel movement. The presence, amount, and duration of blood in the stool should also be elicited. Review of systemsshould seek symptoms of causative disorders, including a change in caliber of the stool or blood in the stool (suggesting cancer). Systemic symptoms suggesting chronic diseases (eg, weight loss) should also be sought. Past medical historyshould ask about known causes, including previous abdominal surgery and symptoms of metabolic (eg, hypothyroidism, diabetes mellitus) and neurologic (eg, Parkinson disease, multiple sclerosis, spinal cord injury) disorders. Prescription and nonprescription drug use should be carefully assessed, with specific questioning about anticholinergic and opioid drugs. A general examination is done to look for signs of systemic disease, including fever and cachexia. Abdominal masses should be sought by palpation. A rectal examination should be done not only for fissures, strictures, blood, or masses (including fecal impaction) but also to evaluate anal resting tone (the puborectalis “lift” when patients squeeze the anal sphincter), perineal descent during simulated evacuation, and rectal sensation. Patients with defecatory disorders may have increased anal resting tone (or anismus), reduced (ie,<2 cm) or increased (ie,>4 cm) perineal descent, and/or paradoxical contraction of the puborectalis during simulated evacuation. Certain findings raise suspicion of a more serious etiology of chronic constipation: Distended, tympanitic abdomen Vomiting Blood in stool Weight loss Severe constipation of recent onset/worsening in older patients Certain symptoms (eg, a sense of anorectal blockage, prolonged or difficult defecation, need for digital disimpaction), particularly when associated with abnormal (ie, increased or reduced) perineal motion during simulated evacuation, suggest a Dyschezia . A tense, distended, tympanitic abdomen, particularly when there is nausea and vomiting, suggests mechanical obstruction. Chronic constipation with modest abdominal discomfort in a patient who has used laxatives for a long time suggests slow-transit constipation. Acute constipation coincident with the start of a constipating drug in patients without red flag findings suggests the drug is the cause. New-onset constipation that persists for weeks or occurs intermittently with increasing frequency or severity, in the absence of a known cause, suggests Colorectal Cancer or other causes of partial obstruction. Excessive straining or prolonged or unsatisfactory defecation, with or without anal digitation, suggests a defecatory disorder. Patients with fecal impaction may have cramps and may pass watery mucus or fecal material around the impacted mass, mimicking diarrhea (overflow diarrhea). Patients with Irritable Bowel Syndrome (IBS) typically have abdominal pain with disordered bowel habits. Patients with chronic constipation who do not meet the criteria for IBS may have functional constipation ( Testing is guided by clinical presentation and the patient's diet history. Constipation with a clear etiology (drugs, trauma, bed rest) may be treated symptomatically without further study. Patients with symptoms of bowel obstruction require flat and upright abdominal x-rays, possibly a water-soluble contrast enema to evaluate for colonic obstruction, and possibly a CT scan or barium x-ray of the small intestine (see also Diagnosis ). Most patients without a clear etiology should have colonoscopy and a laboratory evaluation (complete blood count, thyroid-stimulating hormone, fasting glucose, electrolytes, and calcium). suggests a trial of fiber and/or over-the-counter laxatives. If this trial fails, anorectal manometry with balloon expulsion should be done to identify pelvic floor disorders and dyssynergic defecation ( Evaluation references ). If manometry is negative and the primary complaint is infrequent defecation, colonic transit times should be measured with radiopaque markers (Sitz markers), scintigraphy, or a wireless motility capsule. In patients with chronic constipation, it is important to distinguish between slow-transit constipation (abnormal Sitz marker radiopaque study) and pelvic floor muscle dysfunction (markers retained only in distal colon). (See also the American College of Gastroenterology's 1.Lacy BE, Mearin F, Chang L, et al: Bowel disorders.Gastroenterology150(6):1393–1407, 2016. doi: 10.1053/j.gastro.2016.02.031 2.Rao SCS, Tanisa Patcharatrakul T: Diagnosis and treatment of dyssynergic defecation.J Neurogastroenterol Motil22(3):423–435, 2016. doi: 10.5056/jnm16060 