A 23-year-old woman, gravida 2 para 1, at 37 weeks gestation comes to the labor and delivery unit due to contractions and leakage of fluid for the last 8 hours. She had routine prenatal care until 20 weeks gestation but has not had an appointment since moving across the country. Her prior pregnancy was a term vaginal delivery complicated by intraamniotic infection. Her infant spent 3 weeks in the neonatal intensive care unit for early-onset neonatal sepsis. Temperature is 37.5 C (99.5 F), blood pressure is 120/80 mm Hg, and pulse is 84/min. The patient has grossly ruptured membranes with clear fluid, and the cervix is 3 cm dilated and 30% effaced with the fetal vertex at −1 station. Leukocyte count is 13,000/mm³, hematocrit is 33%, and platelets are 189,000/mm³. Which of following is the indication for intrapartum group B Streptococcus (GBS) prophylaxis in this patient?

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11ec25c8_da3a_db6b_bc81_5bf406adeec4_MD0003_00 Streptococcus agalactiae, or group B Streptococcus (GBS), is a common colonizer of the maternal gastrointestinal and genital tracts. Maternal colonization is typically asymptomatic; however, GBS may be vertically transmitted during vaginal delivery or after rupture of membranes, causing neonatal infection (eg, early-onset neonatal sepsis, pneumonia). Therefore, pregnant patients are screened for GBS colonization with a rectovaginal culture at 36-38 weeks gestation. Those with positive cultures receive penicillin for intrapartum antibiotic prophylaxis (IAP) to prevent vertical transmission to the neonate. However, a subset of patients is at high risk for vertical transmission due to their heavy GBS colonization (ie, high bacterial load). These include patients with GBS bacteriuria or GBS urinary tract infection in the current pregnancy, or those with a prior infant with early-onset neonatal sepsis (which is most commonly caused by GBS). These patients do not undergo routine screening because they are empirically at high risk for GBS transmission and require intrapartum antibiotic prophylaxis (regardless of GBS culture results). (Choices A, C, and E) Intrapartum antibiotic prophylaxis for patients with an unknown GBS status is guided by risk factors for neonatal infection. Patients who require IAP include those who develop intrapartum fever (indicating potential intraamniotic infection), have rupture of membranes for ≥18 hours (due to opportunity for intraamniotic GBS proliferation), or who deliver at <37 weeks gestation (due to an immature fetal immune system). In contrast, patients at ≥37 weeks gestation with no risk factors have a low risk of neonatal GBS disease and do not require IAP. (Choice B) Intraamniotic infection is typically polymicrobial and may involve GBS. However, most neonates of women with an intraamniotic infection do not develop infection or sepsis. Therefore, prior intraamniotic infection without subsequent neonatal infection is not an indication for intrapartum antibiotic prophylaxis in future deliveries. Educational objective: Vertical transmission of group B Streptococcus (GBS) during vaginal delivery causes early-onset neonatal GBS infection (eg, sepsis, pneumonia). Patients with GBS bacteriuria in their current pregnancy or those who delivered a prior infant with early-onset GBS infection are at high risk for transmission; therefore, these patients require intrapartum antibiotic prophylaxis. References: Practice bulletins no. 139: premature rupture of membranes. (http://www.ncbi.nlm.nih.gov/pubmed/24084566) Prevention of perinatal group B streptococcal disease--revised guidelines from CDC, 2010. (http://www.ncbi.nlm.nih.gov/pubmed/21088663)

A 23-Year-Old Woman, Gravida 2 Para 1, at 37 Weeks