(164) Adjunctive azithromycin for unscheduled cesarean delivery complicated by intraamniotic infection

Adjunctive azithromycin at the time of unscheduled cesarean delivery (CD) reduces postoperative infection. Patients with intraamniotic infection (IAI) were excluded in the original trial. We sought to determine if azithromycin is associated with reduced postoperative infection in this population.

Study Design:

Retrospective cohort study of patients with IAI and a singleton delivered by unscheduled CD at ≥24 weeks between 2017-2022 in one healthcare system. IAI was diagnosed using ICD10 codes. Exclusion criteria were PPROM or macrolide allergy. The primary exposure was administration of IV azithromycin 500mg at delivery. The primary outcome was a composite of infection (ICD10 codes for endometritis, SSI, sepsis, or postoperative infection; or post-delivery positive blood, wound, respiratory, or urinary cultures within 6 weeks postpartum). Secondary outcomes included oral antibiotic use after delivery or any urgent (ED or readmission) visit for infection. Patients were matched on delivery BMI, failure to progress CD indication, smoking status, duration of rupture of membranes (h), and pregestational diabetes using coarsened exact matching. Weighted simple logistic regression was performed on matched patients.

Results:

During the study period, 1,366 patients with IAI delivered; 1,158 (84.8%) patients were matched. The overall rate of the primary outcome was 16.7%; 113 patients (9.8%) received oral antibiotics after delivery; and 11 (1.0%) had an urgent postpartum visit for infection (Table). Adjunctive azithromycin was not associated with a lower rate of the primary outcome (OR: 0.88, 95% CI 0.64 – 1.2, p=0.46). It was associated with decreased oral antibiotic use (OR: 0.50, 95% CI 0.39-0.65, p< 0.001) and fewer urgent postpartum visits (OR: 0.22, 95% CI 0.07 – 0.69, p=0.01).

Conclusion:

Adjunctive azithromycin at the time of CD delivery among patients with IAI is not associated with lower rates of postpartum infection. However, it is associated with a reduction in oral antibiotic use, which may suggest a decrease in less severe post-operative infection rates.