Suture thickness and transvaginal cervical cerclage outcomes

BACKGROUND: Cervical cerclage placement has been shown to benefit women who have cervical insufficiency; however, the best type of suture to use for transvaginal cerclage placement is unknown. OBJECTIVE: The objective of the study was to evaluate the association between transvaginal cerclage suture thickness and pregnancy outcomes. STUDY DESIGN: This was a retrospective cohort study of women with a singleton, nonanomalous gestation who underwent history-, ultrasound-, or physical examination-indicated transvaginal cerclage at a single tertiary care center (2013-2016). The primary outcome was gestational age at delivery. Secondary outcomes included preterm birth less than 34 weeks, chorioamnionitis, neonatal intensive care unit admission, and composite neonatal morbidity. Baseline characteristics and outcomes were compared by thickness of suture material: thick 5 mm braided polyester fiber (Mersilene tape) vs thin polyester braided thread (Ethibond) or polypropylene nonbraided monofilament (Prolene) with selection of suture type at the discretion of the provider. The association between thick suture and gestational age at delivery was estimated using Cox proportional hazard regression. Multivariable logistic regression was used to estimate the association between thick suture and the secondary outcomes. Effect modification of cerclage indication was also assessed. RESULTS: A total of 203 women met inclusion criteria: 120 with thick suture (59%) and 83 with thin suture (41%). Of these, 130 women had history-indicated, 35 had ultrasound-indicated, and 38 had examination-indicated cerclages. Compared with women who had thin suture, women with thick suture were more likely to have had a history- or ultrasound-indicated cerclage, rather than examination-indicated cerclage, and more likely to have had a Shirodkar or cervicoisthmic approach, rather than McDonald. Women with thick suture were also more likely to have received progesterone and had placement at earlier gestational age, but there were no differences in cervical examination at placement. After adjusting for confounding factors, thick suture was associated with longer pregnancy duration among women with ultrasound-indicated cerclage (adjusted hazard risk, 0.61, 95% confidence interval, 0.41-0.91) and examination-indicated cerclage (adjusted hazard risk, 0.30, 95% confidence interval, 0.15-0.58) but not with history-indicated cerclage (adjusted hazard risk, 1.27, 95% confidence interval, 0.83-1.94). Thick suture was also associated with lower odds of preterm birth <34 weeks, chorioamnionitis, and neonatal intensive care unit admission, compared with thin suture. CONCLUSION: Thick, compared with thin suture, for transvaginal cervical cerclage, was associated with longer duration of pregnancy among women with ultrasound- and examination-indicated cerclages and lower odds of chorioamnionitis and neonatal intensive care unit admission among all women, regardless of cerclage indication.