Efficacy and safety of cervical pessaries for preventing preterm birth in twin pregnancy: a systematic review

Abstract

Objective To evaluate the efficacy and safety of cervical pessaries in the prevention of preterm birth in twin pregnancy with short cervical length (CL). Methods Based on the principles and methods of Cochrane systematic reviews, we searched the Embase, PubMed, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Ovid-Medline, American College of Physicians (ACP), China Biology Medicine (CBM), China National Knowledge Infrastructure (CNKI), VIP, and Wanfang databases for randomized controlled trial (RCT) to evaluate efficacy and safety of cervical pessaries in the prevention of preterm birth in twin pregnancy with short CL from the date of database inception to January 2018. Related conference papers and dissertations were also searched manually. The methodological quality and data extraction of the included studies were assessed independently by two reviewers followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), and Meta-analysis was conducted using RevMan 5.0 software. The heterogeneity of the treatment was evaluated with the I2 statistic. RR value and its 95%CI were computed for dichotomous data and were combined with a fixed-effects model (I2 50%). Results Five RCTs, involving 2 465 twin pregnancies and 827 of them combined with short CL that pertained to pessary use, met the inclusion criteria. Treatment with a pessary was associated with a significant reduction in the rate of admission to the neonatal intensive care unit (NICU) (RR=0.73, 95%CI: 0.53-1.00, P=0.05). There were higher incidences of vaginal discharge (RR=3.07, 95%CI: 1.29-7.30, P=0.01) and retinopathy of prematurity(ROP) (RR=3.85, 95%CI: 1.19-12.45, P=0.02) in cervical pessary group. No significant differences were found between pessary group and control group among other major maternal and neonatal outcomes. A subgroup analysis of twin pregnancies associated with short CL by different CL values (CL≤ 25 mm or <38 mm) was conducted. Treatment with a pessary was associated with a significant reduction in the rate of preterm birth< 37 gestational weeks (RR=0.81, 95%CI: 0.69-0.94, P=0.007), neonatal sepsis (RR=0.50, 95%CI: 0.30-0.86, P=0.01) and neonatal necrotising enterocolitis (RR=0.43, 95%CI: 0.20-0.95, P=0.04) in twin pregnancy with CL<38 mm. In twin pregnancy with CL ≤25 mm, no significant difference was found between pessary group and control group among major maternal and neonatal outcomes. Conclusions These results suggest that cervical pessary in the twin pregnancy is not likely to facilitate the prevention of PTB, but can significantly reduce the rate of NICU. It seems that cervical pessary has much more protective efficacy in twin pregnancy with a cervical length <38 mm. Key words: Pessaries; Cervix uteri; Pregnancy trimester, second; Twin pregnancy; Cervical length measurement; Systematic review; Pregnancy outcome; Pregnant women