Indomethacin administration at the time of ultrasound-indicated cerclage: is there an association with a reduction in spontaneous preterm birth?

OBJECTIVE: The purpose of this study was to estimate the effect of indomethacin on the prevention of preterm birth (PTB) in women with an ultrasound-indicated cerclage.

STUDY DESIGN: We performed a retrospective cohort study from 1995-2006. Asymptomatic women with a cerclage for a short cervical length (CL), which was defined as <25 mm, between 14-23 weeks 6 days of gestation were included. Women who received indomethacin therapy at the time of ultrasound-indicated cerclage for a short CL were compared with those women who did not. Our primary outcome was spontaneous PTB at <35 weeks of gestation.

RESULTS: Fifty-one women received indomethacin, and 50 women did not. There were no differences between groups regarding previous PTB, gestational age, or CL at time of cerclage. The rate of spontaneous PTB at <35 weeks of gestation was similar between those who received indomethacin (20/51 [39%]) and those who did not (17/50 [34%]; relative risk, 1.15 [95% CI 0.69-1.93]). In our post hoc power analysis, 190 patients would have been needed to detect a 50% reduction in the rate of PTB.

CONCLUSION: Administration of indomethacin around the time of ultrasound-indicated cerclage was not associated with a decrease in spontaneous PTB.