From the Guidelines
At 26 weeks gestation, this patient should not be screened for Group B Streptococcus (GBS) colonization, as the recommended screening time is between 35-37 weeks gestation. According to the Centers for Disease Control and Prevention (CDC) guidelines 1, all pregnant women should be screened at 35-37 weeks' gestation for vaginal and rectal GBS colonization. The patient's history of GBS colonization in a previous pregnancy is not an indication for intrapartum prophylaxis in the current pregnancy, as colonization can change between pregnancies.
The patient's minimal pedal edema and normal urinalysis results do not indicate a need for immediate screening or treatment. The CDC guidelines recommend that women with GBS isolated from the urine in any concentration during their current pregnancy should receive intrapartum chemoprophylaxis, but this patient's urinalysis results are normal.
Key points to consider in this patient's care include:
- Screening for GBS colonization is recommended at 35-37 weeks gestation, not at 26 weeks.
- A history of GBS colonization in a previous pregnancy does not necessitate intrapartum prophylaxis in the current pregnancy.
- Women with GBS bacteriuria at any point during pregnancy are at increased risk for early-onset GBS disease and should receive intrapartum antibiotic prophylaxis, but this patient does not have GBS bacteriuria.
- Intrapartum antibiotic prophylaxis should be given to all pregnant women who test positive for GBS colonization at 35-37 weeks gestation, except in the instance of cesarean delivery performed before onset of labor on a woman with intact amniotic membranes.
The most recent and highest quality study supporting this recommendation is from the CDC guidelines published in 2010 1. This study provides the most up-to-date and evidence-based recommendations for the prevention of perinatal Group B Streptococcal disease.
From the Research
Patient Presentation
The patient is a 33-year-old gravida 2 para 1 woman at 26 weeks gestation with a history of Group B Streptococcus (GBS) colonization, presenting with minimal pedal edema and normal urinalysis results.
Relevant Guidelines
- According to 2, the American College of Obstetricians and Gynecologists recommends universal prenatal screening for GBS by vaginal-rectal culture between 36 0/7 and 37 6/7 weeks of gestation.
- 3 suggests that screening for GBS should occur between 36 weeks and the end of the 37th week, and that patients with a history of GBS colonization in prior pregnancy who are GBS-unknown in this current pregnancy and present with labor should receive intrapartum prophylaxis.
- 4 recommends maternal intrapartum antibiotic prophylaxis based on antenatal screening for GBS colonization, with the optimal window for screening changed to 36 0/7 to 37 6/7 weeks of gestation.
Test Indications
- Given the patient's history of GBS colonization and current gestational age, the following tests may be indicated:
- Vaginal-rectal culture for GBS screening between 36 0/7 and 37 6/7 weeks of gestation, as recommended by 2 and 3.
- Urinalysis to monitor for any changes in the patient's condition, although the current results are normal.
- Penicillin allergy testing, as recommended by 4, to determine the appropriate antibiotic prophylaxis if needed.
Key Considerations
- The patient's history of GBS colonization is a significant risk factor for neonatal GBS disease, as highlighted by 2 and 3.
- The current gestational age of 26 weeks is earlier than the recommended screening window, but the patient's history of GBS colonization may require earlier consideration of intrapartum antibiotic prophylaxis, as suggested by 3.