Interventions for women with premature cervical dilatation and exposed fetal membranes to prevent pregnancy loss and preterm birth – A systematic review and meta-analysis

Introduction: The management of women with premature cervical dilatation and exposed unruptured fetal membranes remains uncertain and controversial. Treatment options may include expectant management or emergency cervical cerclage (ECC). Little is known regarding the effectiveness of individual interventions, or additional therapies. This systematic review aims to summarise all existing evidence to improve understanding of the treatment options and pregnancy outcomes for women presenting with premature cervical dilatation.

Methods: Databases were searched using a prospective protocol (CRD42021286275). Studies were eligible for inclusion across five distinct comparison groups if they included women with premature cervical dilatation and reported clinical outcomes. Primary outcome was pregnancy loss (miscarriage, stillbirth, neonatal death and termination of pregnancy). Planned subgroups included singletons and twins and low-cervical or high-cervical suture. Pairwise random effects meta-analysis calculated in RevMan5.4, single arm random effects proportional meta-analysis calculated using RevMan and R studio. Risk of bias was assessed using Cochrane Risk of Bias tool and Joanna Briggs Institute checklists.

Results: 6781 abstracts were screened, and 177 (four randomised controlled trials) studies included in the five analysis groups. Women receiving ECC were significantly less likely to experience pregnancy loss (combined RR 0.48 95 %CI 0.39–0.59 singleton RR 0.48 95 %CI 0.34–0.67 twin only RR 0.39 95 %CI 0.260.58) compared to expectant management. Adjuvant amnioreduction with ECC was not found to reduce pregnancy loss (RR 1.12 (95 % CI 0.73–1.72) or any other outcomes compared to ECC without amnioreduction. Women were significantly more likely to experience pregnancy loss (RR3.85 95 %CI 3.13–4.74) after ECC compared to planned cerclage. The probability of intra-operative rupture of membranes at ECC insertion was 3.3 % (95 %CI 1.8–5.1) and the probability of an ECC attempt being abandoned was 2.6 % (95 %CI 1.1–4.6 %).

Discussion: ECC appears to reduce the risk of pregnancy loss for both singletons and twins although the overall quality of evidence is poor. It is important that women are counselled regarding the outcomes following cerclage according to indication. Pregnancy complications are common after ECC although the rates of intra-operative complications are lower than may be anticipated. Randomised trials remain imperative for understanding the role of ECC and adjunctive treatments in preventing pregnancy loss in this condition.