(599) Utility of Cervical Length Measurement within 24 hours Post Transvaginal Cervical Cerclage Placement

There are currently no recommendations by the Society of Maternal Fetal Medicine regarding the benefit of cervical length measurement post cerclage placement. Our objective was to determine if a post-cerclage cervical length measurement (TVCL) within 24 hours of placement can aid in counseling patients at risk for preterm birth.

Study Design: A prospective cohort of singleton non-anomalous pregnancies at a large academic medical center between December 2021 to May 2022 were included. All cerclages included in the analysis were either ultrasound or physical exam indicated. Pregnancies with a TVCL post-cerclage < 25 mm were compared to those with a TVCL post-cerclage ≥25 mm.  The primary outcome was delivery < 34 weeks. Secondary outcomes included: latency from cerclage placement to delivery and delivery < 37 weeks’ gestation. Descriptive statistics were completed using chi-square or t-test when appropriate. Survival analysis was done using a Cox regression model.

Results:

66 patients met the inclusion criteria. 34 (51.5%) had a TVCL < 25 mm and 32 (48.5%) had a TVCL ≥25 mm. Maternal demographics were similar between the two groups. The use of vaginal progesterone and intramuscular 17-hydroxyprogesterone use were similar between both groups (p=0.89 and p=0.85). The rate of the primary outcome which was delivery < 34 weeks was significantly higher in those pregnancies with a TVCL of < 25 mm, 52.9% (n=18) vs 28.1% (n=9) in the TVCL of >25 mm (p=0.04). Pregnancies with a post-cerclage TVCL of < 25 mm were more likely to deliver before 37 weeks’ gestation (p=0.006). The latency (days) from cerclage placement to delivery was significantly shorter in the TVCL < 25mm group; 77.2 ± 48.1 vs 102.2 ± 37.3 in ≥ 25 mm group (p= 0.04). Hazard ratio 0.54 (95% CI 0.31,0.92, p=0.02).

Conclusion:

A TVCL < 25 mm within 24 hours of cerclage placement is a significant risk factor for delivery before 34 weeks and 37 weeks gestation. These patients should receive close follow up and monitoring for preterm labor and/or premature rupture of membranes with consideration for corticosteroids when appropriate.