A healthy 22-year-old woman, gravida 2 para 1, comes to her physician for a routine prenatal visit. She is 28 weeks pregnant, feeling well, and gaining weight appropriately. She has no bleeding, fluid leakage, or uterine contractions and feels fetal movement. The patient recently ended her relationship with the father of the baby. Her first trimester prenatal testing results were as follows: Which of the following is the most appropriate next step at this gestational age in pregnancy?

Question

A healthy 22-year-old woman, gravida 2 para 1, comes to her physician for a routine prenatal visit.  She is 28 weeks pregnant, feeling well, and gaining weight appropriately.  She has no bleeding, fluid leakage, or uterine contractions and feels fetal movement.  The patient recently ended her relationship with the father of the baby.  Her first trimester prenatal testing results were as follows:  Which of the following is the most appropriate next step at this gestational age in pregnancy?

Quizplus · Accepted Answer

11ec25c8_da83_7daf_bc81_395f23a6554e_MD0003_00 At the first prenatal visit, patients are routinely tested for blood type (A, B, AB, O), Rh (D) status (positive or negative), and the presence of any red blood cell antibodies (antibody screen). The antibody screen may be positive in women who have formed antibodies from exposure to another's blood (eg, blood transfusion, prior pregnancy). This process of forming positive antibodies is called alloimmunization or sensitization. The antibody screen is particularly important in an Rh (D)-negative multiparous woman to look for anti-D antibodies that may have formed in response to an Rh (D)-positive fetus. This woman's negative antibody screen in the first trimester indicates that she is not alloimmunized. alloimmunization or sensitization The administration of anti-D immune globulin reduces the Rh (D)-negative woman's likelihood of developing antibodies to the fetal D antigen if her fetus is Rh (D) positive, which remains unknown until birth. It is routinely administered at 28-32 weeks gestation and again within 72 hours of delivery if the baby is found to be Rh (D) positive. The initial timing of 28-32 weeks is selected because the half-life of anti-D immune globulin is about 6 weeks, which would cover any potential future exposure to fetal red blood cells through most of the third trimester. (Choice B) Routine Group B Streptococcus (GBS) rectovaginal screening should be performed at 35-37 weeks gestation as the results are valid for ~5 weeks. The purpose is to identify women who are colonized so that they can receive intrapartum antibiotic prophylaxis to prevent transmission to the baby. GBS colonization may be transient; for example, a patient who is negative at 28 weeks can become positive at 37 weeks. Testing at 28 weeks is too early because there is no reason to assume the patient will deliver prematurely. (Choice C) Pregnant women should be screened for HIV infection at the first prenatal visit as early initiation of anti-retroviral medications can significantly decrease disease transmission to the fetus. Rescreening in the 3rd trimester is recommended for high-risk individuals (eg, injection drug users, multiple sexual partners) and not this patient. (Choice D) Rubella immunity is evaluated as part of the prenatal panel in pregnant women. However, the measles-mumps-rubella live-attenuated vaccine is contraindicated during pregnancy. It should be administered postpartum to nonimmune women, such as this patient. (Choice E) Pregnant women should undergo screening and treatment for asymptomatic bacteriuria in the first trimester. Asymptomatic bacteriuria in pregnancy has a 40% risk of progressing to pyelonephritis because smooth muscle relaxation and ureteral dilation allow urine to ascend from the bladder to the kidneys. The lack of risk factors (eg, urinary tract anomalies, sickle cell disease) and a negative culture in the first trimester make rescreening unnecessary. Educational objective: Blood typing and antibody screening should be performed at the first prenatal visit. An Rh (D)-negative woman with a negative antibody screen is unsensitized (not alloimmunized) and should receive anti-D immune globulin. Anti-D immune globulin should be given at 28-32 weeks gestation and again after delivery if the baby is Rh positive. References: ACOG practice bulletin - prevention of Rh D alloimmunization. (http://www.ncbi.nlm.nih.gov/pubmed/10458556)

A Healthy 22-Year-Old Woman, Gravida 2 Para 1, Comes to Her