What is the Group B Streptococcus (GBS) risk assessment and management for a laboring female with unknown GBS status?

GBS Risk Assessment for Laboring Female with Unknown GBS Status

For a laboring female with unknown GBS status, intrapartum antibiotic prophylaxis (IAP) should be administered if any of the following risk factors are present: delivery at <37 weeks' gestation, amniotic membrane rupture ≥18 hours, or intrapartum temperature ≥100.4°F (≥38.0°C). 1

Risk Assessment Algorithm

Step 1: Determine if any of these indications for IAP are present:

• Previous infant with invasive GBS disease 1
• GBS bacteriuria during any trimester of the current pregnancy 1
• Unknown GBS status with any of the following risk factors:
  • Delivery at <37 weeks' gestation 1
  • Amniotic membrane rupture ≥18 hours 1
  • Intrapartum temperature ≥100.4°F (≥38.0°C) 1
  • Positive intrapartum NAAT (nucleic acid amplification test) for GBS (if available) 1

Step 2: If the patient is in preterm labor (<37 weeks):

• Obtain vaginal-rectal swab for GBS culture 1
• Start GBS prophylaxis immediately 1
• Assess if patient is in true labor:
  • If yes: continue prophylaxis until delivery 1
  • If no: discontinue prophylaxis 1

Step 3: For patients with premature rupture of membranes at <37 weeks:

• Obtain vaginal-rectal swab for GBS culture 1
• Start antibiotics for latency or GBS prophylaxis 1
• Continue antibiotics according to clinical situation 1

Important Considerations

Antibiotic Timing and Effectiveness

• IAP is most effective when administered at least 4 hours before delivery 2
• Even when administered <4 hours before delivery, IAP still provides some protection 3, 2
• For women at term with unknown GBS status and no risk factors, IAP is not indicated 1

Special Situations

• Cesarean delivery before labor onset with intact membranes does not require GBS prophylaxis, regardless of GBS status or gestational age 1
• Women with suspected amnionitis should receive broad-spectrum antibiotic therapy that includes coverage for GBS rather than GBS prophylaxis alone 1

Pitfalls to Avoid

• Do not administer antibiotics before the intrapartum period to eradicate GBS colonization, as this is ineffective and may cause adverse consequences 1
• Do not miss the opportunity to provide IAP for preterm deliveries, as preterm infants have twice the incidence of early-onset GBS disease compared to term infants 2
• Do not rely on GBS screening results from previous pregnancies for management decisions in the current pregnancy 1
• Do not withhold IAP in women with prolonged rupture of membranes at term, as this is a significant risk factor for GBS sepsis 4

Evidence Quality

• The recommendations are based on high-quality evidence from the CDC guidelines, which have demonstrated an 80% reduction in early-onset GBS disease since implementation 2
• The risk-based approach for women with unknown GBS status has been shown to be effective in reducing neonatal GBS infections, though universal screening with IAP for colonized women is more effective overall 1, 2