Short cervix on ultrasound: does indomethacin prevent preterm birth?

Objective: Our aim was to estimate if indomethacin therapy prevents preterm birth (PTB) in women with a short cervical length (CL) on transvaginal ultrasound (TVU).

Study Design: Individual-level data from all randomized trials including asymptomatic women with a short CL on TVU were analyzed for use of indomethacin at the time of the short CL. The trials eligible would be ones that randomized women with a short CL <25 mm, identified between 14 and 27 weeks. The eligible trials randomized such women to receive either cerclage or no cerclage. Only women who did NOT receive cerclage were analyzed. Exclusion criteria were major fetal anomaly and cerclage. We compared demographics, risk factors, and outcomes in women who, at the time of the short CL, received indomethacin or not. Primary outcome was PTB <35 weeks.

Results: Three of the 4 randomized trials identified had databases which recorded indomethacin use at the time of the short CL. A total of 139 women with a short CL <25 mm identified at 14 to 27 weeks were identified. Of these women, 99 (71.2%) received indomethacin, and 40 (28.8%) did not. Demographics and risk factors, including previous PTB (45.5% vs 62.5%; P = .11), were similar in the 2 groups. The primary outcome of PTB <35 weeks occurred in 29.3% (29/99) of women who received indomethacin, and 42.5% (17/40) of women who did not receive indomethacin (RR 0.69, 95% CI 0.44-1.13). PTB <24 weeks occurred in 1.0% (1/99) versus 7.5% (3/40), respectively (RR 0.14; 95% CI 0.02-0.92). Incidence of perinatal death was similar in the 2 groups (6% vs 10%; RR 0.61, 95% CI 0.19-1.95).

Conclusion: Indomethacin therapy for asymptomatic women who have a short CL <25 mm on TVU at 14 to 27 weeks and do not receive a cerclage did not prevent spontaneous PTB <35 weeks, but did prevent PTB <24 weeks. Further research including larger numbers and a randomized trial design is necessary to further clarify the effectiveness as well as the risks of this therapy.