(512) Azithromycin to improve latency in exam-indicated cerclage: a multicenter randomized control trial (ALEC)

While prophylactic azithromycin has been shown to increase latency in the setting of cervical shortening, its use in physical exam-indicated cerclage (PEIC) has been understudied. Our objective is to determine whether adding azithromycin prior to PEIC increases gestational latency to usual care (cefazolin and indomethacin).

Study Design:

This RCT included pregnant people with singleton gestations < 24 weeks gestational age (GA) planning a PEIC at one of four sites across the United States. Participants were randomized 1:1 to usual care (cefazolin 1-2 g IV and indomethacin 50 mg IV preoperatively, then 2 additional doses at 8 and 16 hours postoperatively) or usual care plus azithromycin (azithromycin 1g IV once perioperatively). Primary outcome was gestational latency (days) from cerclage placement to delivery. Secondary outcomes included preterm birth ( < 37, < 34, < 32, < 28, and  < 24 weeks), GA at birth, chorioamnionitis, birthweight, NICU admission, and composite neonatal morbidity and mortality. Fifty participants needed to be randomized to demonstrate a 20±25 days improvement in latency with 80% power. Assuming a 10% loss to follow-up, we aimed to recruit 55 individuals. Kaplan-Meier survival curve, Mann Whitney U test, and chi squared analyses were conducted. The study was registered at clinicaltrials.gov (NCT05132829).

Results:

A total of 55 participants were randomized from December 2021 to September 2023; 27 to usual care, 27 to adjunctive azithromycin, and 1 excluded from analysis when found not to meet study criteria after randomization. Protocol adherence was 100% for each arm. The median gestational latency after PEIC did not differ between the usual care and azithromycin groups (median difference -1 day, 95% CI -20 to 26 days; Figure). Additional secondary obstetric and neonatal outcomes were similar between groups (Table).

Conclusion:

A single perioperative dose of azithromycin in addition to usual care (cefazolin and indomethacin) does not improve latency to delivery or other obstetric or neonatal outcomes for individuals undergoing PEIC.