(536) Predictors of Pregnancy Duration Among Women Undergoing Exam-Indicated Cerclage: A Survival Analysis Approach

To identify socio-demographic, clinical and sonographic predictors of pregnancy prolongation up to 32 weeks among women undergoing an exam-indicated cerclage.

 

Study Design:

We conducted a retrospective cohort study of women undergoing a cervical cerclage at a single tertiary academic center between 2008 to 2020. Data pertaining to maternal demographics, obstetric course, sonographic cervical length and cerclage operative technique were abstracted for women undergoing exam-indicated cerclage with a singleton gestation. Co-variates with P≤0.2 in the unadjusted survival analyses were considered for incorporation into an adjusted Cox proportional-hazards model evaluating factors associated with pregnancy prolongation up to 32 weeks.

 

Results:

Out of 1086 transvaginal cervical cerclages performed over the study period, 285 cases of exam–indicated cerclage were included in analyses. In the unadjusted survival analyses 5 factors were associated with longer pregnancy duration: multiparity with recent birth ≥32 weeks (P < .001), use of Mersilene suture (P .03), evidence of prior cervical trauma (P .03), gestational age at cerclage placement (P .04), and concomitant progesterone use (P < .01) while 4 were associated with shorter pregnancy duration: preoperative cervical dilation (P < .0001), post-operative cervical length (P < .0001), and administration of a penicillin antibiotic (P .03) and/or multiple doses of indomethacin (P < .01).  An adjusted Cox proportional-hazards model incorporated 5 of these covariates and 3 with an unadjusted P value ranging from .05 to .2 that were independently predictive of pregnancy prolongation up to 32 weeks. Delivery < 32 weeks gestation occurred in 99 (35%) of cases. The bias-corrected bootstrapped (1000 repetitions) AUROC for a logistic regression model predictive of delivery < 32 weeks containing these 8 covariates was 0.84 (95% CI 0.77-0.87).

Conclusion:

A survival analyses approach using 8 covariates as shown in our model offers valuable clinical insight into predictors of pregnancy prolongation up to 32 weeks among women undergoing an exam-indicated cerclage.