(329) Clinical Chorioamnionitis Risk in Term GBS Patients With or Without Antibiotics Before Balloon Insertion

To compare the risk of clinical chorioamnionitis among Group B Streptococcus (GBS)-colonized pregnant patients who underwent cervical ripening with a catheter balloon, between those treated and not treated with prophylactic antibiotics prior to insertion of the catheter balloon.

Study Design:

This is a retrospective study of term singleton pregnant women with confirmed GBS colonization who underwent induction of labor for medical indications during 2018-2023 at two tertiary centers. At one center, the patients received prophylactic intravenous ampicillin (2g every 6h), starting 30 minutes prior to the catheter balloon insertion and continued until delivery. At the other center, routine prophylactic antibiotics were not administered; and antibiotics were initiated only at the onset of active labor. The primary outcome was clinical chorioamnionitis. Secondary outcomes included maternal postpartum infections and neonatal outcomes. Multivariate logistic regression was used to adjust for potential confounders.

Results:

Included were 144 patients: 75 treated with prophylactic antibiotics and 69 not treated. Baseline maternal and obstetric characteristics were comparable. Among those treated compared to those not treated, the rates were lower of intrapartum fever (2.7% vs. 15.9%, p=0.005) and clinical chorioamnionitis (0% vs. 8.7%, p=0.002) (Figure). Statistically significant differences were not observed between the groups, in postpartum infections, cesarean delivery rates, or neonatal outcomes. In the multivariate analysis, not receiving prophylactic antibiotics prior to catheter balloon insertion was independently associated with an increased risk of clinical chorioamnionitis (p=0.010) (Table).

Conclusion:

Antibiotic prophylaxis prior to catheter balloon insertion in GBS-colonized patients was associated with lower rates of maternal fever and clinical chorioamnionitis. Randomized controlled trials are warranted to confirm these findings and to guide clinical practice regarding the role of prophylactic antibiotic use during mechanical induction of labor.