The effect of an exam-indicated cerclage before 24 weeks of gestation to prevent preterm birth: A systematic review and meta-analysis

Abstract

The effect of an exam-indicated cerclage (EIC) remains uncertain due to limited evidence from reviews covering pregnancies beyond this timeframe. With the 24-week mark serving as an international threshold for neonatal care initiation, the aim of this systematic review was to evaluate the available literature on the effectiveness of an EIC before 24 weeks of gestation. MEDLINE, EMBASE, Web of Science, CENTRAL, clinicaltrials.gov and WHO-ICTRP were searched for randomized controlled trials, cohort and case-control studies comparing EIC with expectant management in singleton pregnancies with cervical dilation ≤ 5 cm between 14 and 24 weeks of gestation to prevent preterm birth (PTB) < 37 weeks of gestation. Secondary outcomes included obstetrical and neonatal outcomes. Quality assessment was preformed using Newcastle-Ottawa Scale. Analyses were conducted using R(studio) version 3.6.1. and outcomes stated as odds ratios (OR) with 95 % confidence intervals (CI). Prospero: #CRD42019137400. The search yielded 787 potential studies. Four studies non-randomized (retrospective) could be included. Quality assessment showed overall good quality. The main weaknesses were retrospective designs, small sample sizes and the poor comparability of the intervention and control groups. The study population resulted in 215 women, among whom 163 (76 %) underwent cerclage placement and 52 (24 %) were expectantly managed. EIC compared with expectant management was associated with significant lower rates of PTB before 37 weeks (71.2 % vs 94.2 %; OR 0.11; 95 % CI 0.03–0.35), 34 weeks (49.1 % vs 86.5 %; OR 0.10; 95 % CI 0.03–0.31), 32 weeks (43.0 % vs 80.0 %; OR 0.13; 95 % CI 0.04–0.43), 28 weeks (43.0 % vs 75.0 %; OR 0.19; 95 % CI 0.07–0.51) and 24 weeks (23.3 % vs 50 %; OR 0.29; 95 % CI 0.13–0.65) of gestation, significant prolongation of the pregnancy (mean difference 39.14 days; 95 %CI 30.58–47.71; p-value <0.0001) and a greater gestational age at delivery (mean difference 4.91 weeks; 95 % CI 2.32–7.49; p-value 0.0002) compared to expectant management. The current literature suggests that EIC before 24 weeks of gestation is associated with improved pregnancy outcomes compared to expectant management. The results are limited by the lack of randomised trials and studied neonatal outcomes plus the potential for bias in the included studies.