A 28-year-old primigravid woman at 30 weeks gestation comes to the office for a routine prenatal visit. The patient has had an uncomplicated prenatal course with normal prenatal laboratory results, including a negative urine culture during the first trimester. She feels well and has had no contractions, leakage of fluid, or vaginal bleeding. The patient has no chronic medical conditions or medication allergies. Temperature is 37.2 C (99 F), blood pressure is 110/70 mm Hg, and pulse is 88/min. Physical examination, including fetal heart tones, is normal. At the end of the visit, the patient mentions that her niece recently died from neonatal group B streptococcal infection after preterm delivery at 36 weeks gestation and she is afraid that this could happen to her baby. Which of the following is the most appropriate response to this patient?

Question

A 28-year-old primigravid woman at 30 weeks gestation comes to the office for a routine prenatal visit.  The patient has had an uncomplicated prenatal course with normal prenatal laboratory results, including a negative urine culture during the first trimester.  She feels well and has had no contractions, leakage of fluid, or vaginal bleeding.  The patient has no chronic medical conditions or medication allergies.  Temperature is 37.2 C (99 F), blood pressure is 110/70 mm Hg, and pulse is 88/min.  Physical examination, including fetal heart tones, is normal.  At the end of the visit, the patient mentions that her niece recently died from neonatal group B streptococcal infection after preterm delivery at 36 weeks gestation and she is afraid that this could happen to her baby.  Which of the following is the most appropriate response to this patient?

Quizplus · Accepted Answer

11ec25c8_da39_54c8_bc81_2109babfaac6_MD0003_00 Streptococcus agalactiae, or group B Streptococcus (GBS), is a common colonizer of the maternal gastrointestinal and genital tracts. Although GBS is typically asymptomatic in pregnant women, it can be vertically transmitted to the neonate during vaginal delivery or with rupture of membranes, resulting in early-onset neonatal GBS infection (eg, sepsis, pneumonia). GBS screening and use of intrapartum antibiotic prophylaxis in GBS-positive patients have markedly reduced the incidence of neonatal GBS infection. Maternal colonization with GBS can be transient; therefore, screening is performed 3-5 weeks before the estimated delivery date, which most accurately predicts maternal GBS status at delivery (Choice B). Because most women deliver by 40-42 weeks gestation, screening is at 36-38 weeks gestation by rectovaginal culture. (Choice A) A personal history of an infant with early-onset GBS disease is a risk factor for neonatal GBS infection affecting future children. Patients with this history do not require screening because they are presumed to be persistently and heavily colonized with GBS and therefore always require intrapartum antibiotic prophylaxis. In contrast, a family history (eg, this patient's niece) is not a risk factor for neonatal GBS infection. (Choice D) Infants delivered at <37 weeks gestation are at greater risk for neonatal GBS infection because of immature immune systems, but GBS infection can affect deliveries at any gestational age (term or preterm). (Choice E) Screening earlier (eg, <36 weeks gestation) can miss patients who are not colonized with GBS until later in pregnancy; or, it can result in unnecessary antibiotic prophylaxis (ie, increased risk of bacterial resistance) in patients who are no longer colonized with GBS at delivery. Educational objective: Group B Streptococcus (GBS) screening is by rectovaginal culture performed at 36-38 weeks gestation. Patients with a positive GBS culture require intrapartum antibiotic prophylaxis to reduce the risk of early-onset neonatal GBS infection. References: Prevention of perinatal group B streptococcal disease-revised guidelines from CDC, 2010. (http://www.ncbi.nlm.nih.gov/pubmed/21088663)

A 28-Year-Old Primigravid Woman at 30 Weeks Gestation Comes to the Office