gynecology and obstetrics
Evaluation of the Obstetric Patient
Testing
 Diagnosis involves urine tests and blood tests. Initial laboratory evaluation is thorough; some components are repeated during follow-up visits (see table Components of Routine Prenatal Evaluation). If a woman has Rh-negative blood, she may be at risk of developing Rh(D) antibodies, and if the father has Rh-positive blood, the fetus may be at risk of developing Hemolytic Disease of the Fetus and Neonate . Rh(D) antibody levels should be measured in pregnant women at the initial prenatal visit and again at about 26 to 28 weeks. At that time, women who have Rh-negative blood are given a prophylactic dose of Rh(D) immune globulin. Additional measures may be necessary to prevent development of maternal Rh antibodies. Urine is also tested for protein. Proteinuria before 20 weeks gestation suggests kidney disease. Proteinuria after 20 weeks gestation may indicate Preeclampsia and Eclampsia . Generally, women are routinely screened for gestational diabetes between 24 and 28 weeks using a 50-g, 1-hour Diabetes . However, if women have significant risk factors for gestational diabetes, they are screened during the 1st trimester. These risk factors include Diabetes Mellitus in Pregnancy or a macrosomic neonate (weight > 4500 g at birth) in a previous pregnancy Unexplained fetal losses A strong family history of diabetes in 1st-degree relatives A history of persistent glucosuria Body mass index (BMI) > 30 kg/m2 Polycystic Ovary Syndrome (PCOS) with If the 1st-trimester test is normal, the 50-g test should repeated at 24 to 28 weeks, followed, if abnormal, by a 3-hour test. Abnormal results on both tests confirms the diagnosis of gestational diabetes. Women at high risk of aneuploidy (eg, those > 35 years, those who have had a child with Down syndrome) should be offered screening with Diagnosis . In some pregnant women, blood tests to screen for thyroid disorders (measurement of thyroid-stimulating hormone [TSH]) are done. These women may include those who Have symptoms Come from an area where moderate to severe iodine insufficiency occurs Have a family or personal history of thyroid disorders Have type 1 diabetes Have a history of infertility, preterm delivery, or miscarriage Have had head or neck radiation therapy Are morbidly obese (BMI > 40 kg/m2) Are > 30 years Most obstetricians recommend at least one ultrasound examination during each pregnancy, ideally between 16 and 20 weeks, when estimated delivery date (EDD) can still be confirmed fairly accurately and when placental location and fetal anatomy can be evaluated. Estimates of gestational age are based on measurements of fetal head circumference, biparietal diameter, abdominal circumference, and femur length. Measurement of fetal crown-rump length during the 1st trimester is particularly accurate in predicting EDD: to within about 5 days when measurements are made at<12 weeks gestation and to within about 7 days at 12 to 15 weeks. Ultrasonography during the 3rd trimester is accurate for predicting EDD to within about 2 to 3 weeks. for Prenatal Ultrasonography include Investigation of abnormalities during the 1st trimester (eg, indicated by abnormal results of noninvasive maternal screening tests) Risk assessment for chromosomal abnormalities (eg, Down syndrome) including nuchal translucency measurement Need for detailed assessment of fetal anatomy (usually at about 16 to 20 weeks), possibly including fetal echocardiography at 20 weeks if risk of congenital heart defects is high (eg, in women who have type 1 diabetes or have had a child with a congenital heart defect) Detection of multifetal pregnancy, hydatidiform mole, polyhydramnios, placenta previa, or ectopic pregnancy Determination of placental location, fetal position and size, and size of the uterus in relation to given gestational dates (too small or too large) Ultrasonography is also used for needle guidance during Chorionic Villus Sampling , If ultrasonography is needed during the 1st trimester (eg, to evaluate pain, bleeding, or viability of pregnancy), use of an endovaginal transducer maximizes diagnostic accuracy; evidence of an intrauterine pregnancy (gestational sac or fetal pole) can be seen as early as 4 to 5 weeks and is seen at 7 to 8 weeks in>95% of cases. With real-time ultrasonography, fetal movements and heart motion can be directly observed as early as 5 to 6 weeks. Conventional x-rays can induce spontaneous abortion or congenital malformations, particularly during early pregnancy. Risk is remote (up to about 1/million) with each x-ray of an extremity or of the neck, head, or chest if the uterus is shielded. Risk is higher with abdominal, pelvic, and lower back x-rays. Thus, for all women of childbearing age, an imaging test with less ionizing radiation (eg, ultrasonography) should be substituted when possible, or if x-rays are needed, the uterus should be shielded (because pregnancy is possible). Medically necessary x-rays or other imaging should not be postponed because of pregnancy. However, elective x-rays are postponed until after pregnancy. 