(414) Maternal and obstetric factors associated with successful cerclage treatment: a prediction model

Objective: Cervical cerclage treatment effectively reduces the risk of recurrent preterm birth (PTB) in specific subgroups. This study aimed to identify maternal and obstetric factors influencing success of cerclage treatment (i.e. no PTB < 32 weeks) to develop a prediction model.

Study Design: This multicenter prospective cohort study analyzed data of the PC-study (NTR4415) and associated observational cohort. We included patients with prior sPTB < 34 weeks and a singleton pregnancy who received a history-based (HB) or an ultrasound-indicated (UI) cerclage. Primary outcome was PTB < 32 weeks. Maternal and obstetric factors were included in multivariate logistic regression (MLR) and a risk model was composed for the HB- and UI group. Subsequently, outcomes were stratified by risk scores (high, medium and low).

Results: In total, 222 patients received cerclage treatment. PTB < 32 weeks occurred in 43/222 cases (19.4%), of which 13/85 in the HB group (15.3%) and 30/137 (21.9%) in the UI group. In the total group, MLR showed that higher maternal age (p=0.04), non-Caucasian ethnicity (p=0.02) and smoking (p=0.045) were associated with decreased cerclage success (i.e. higher PTB < 32 weeks). In the HB group, event rates were considered too low for proper MLR. In the UI group, higher maternal age (p=0.008), smoking (p=0.005), lower gestational age at placement (p< 0.001) and lower CL (p=0.004) were associated with decreased cerclage success. Individual risk scores in this group were calculated using the composed risk model. Scores < -1.7 were considered low-risk, -1.7 to 0 medium-risk and > 0 high risk. For high-risk patients, the UI-model had a positive predictive value (PV) of 81.3% for occurrence of PTB < 32 weeks. Low-risk patients had a PV of 91.2% for no PTB < 32 weeks. The AUC of the ROC-curve was 0.81 (95% CI 0.72 – 0.90).

Conclusion: Several maternal and obstetric risk factors significantly influence the success rate of cerclage treatment. The developed risk model effectively stratifies patients with an UI cerclage into high, medium, and low risk categories and can be a valuable tool in counseling patients.