(990) Prediction of pregnancy duration up to 34 weeks gestation after ultrasound-indicated cerclage placement

Friday, February 10, 2023

3:30 PM – 5:00 PM

Objective: Ultrasound (US)-indicated cerclage is an intervention that has been shown to significantly improve neonatal survival in pregnancies complicated by a history of spontaneous preterm birth (sPTB) with cervical length (CL) < 25mm, and may also reduce risk for those without a history of sPTB when CL is < 10-15mm. Our aim is to evaluate factors associated with cerclage placement for short CL in these two groups and pregnancy duration up to 34 weeks gestational age (GA).

Study Design: Retrospective analysis of 1086 pregnancies at a single tertiary-care institution (2008-2020) that underwent cerclage placement. This subgroup analysis examined 185 pregnancies that underwent cerclage for short CL and compared data between groups with and without history of sPTB. Cox proportional hazards model incorporated demographic and clinical factors independently associated with pregnancy duration up to 34 weeks.

Results: Of 185 women undergoing cerclage placement for short CL, 107 (57.8%) had a history of prior sPTB while 78 (42.2%) did not. Those without a history of sPTB were more likely to be older (P=.04), nulliparous (P < .0001), prescribed vaginal progesterone (P < .01), and given indomethacin (P=.043) as compared to women with history of prior sPTB. They tended to have shorter preoperative CL (P < .0001) and underwent cerclage placement at a later GA (P < .001). After adjustment for preoperative CL and GA at cerclage placement, factors independently associated with shorter pregnancy duration include tobacco use, ≥ 2 prior sPTB, and postoperative CL ≤ 20mm. Delivery before 34 weeks occurred in 39 (21%) cases. Bias-corrected bootstrapped (1000 replicates) AUROC for a logistic regression model predictive of PTB < 34 weeks with these same 5 covariates is 0.76 (95% CI 0.63-0.79). History of one prior sPTB was not associated with pregnancy prolongation (P=.06).

Conclusion: A model comprising 5 demographic and clinical factors is predictive of pregnancy duration up to 34 weeks after US-indicated cerclage placement.

Primary & Presenting Author(s)

Emily Zantow, MD
MFM Fellow
St. Louis University School of Medicine
St. Louis, Missouri, United States

Coauthor(s)

Leah A. Hong, BA, MD (she/her/hers)
Saint Louis University School of Medicine
St. Louis, Missouri, United States
Jennifer E. Powel, MD
Saint Louis University School of Medicine
Long Branch, New Jersey, United States
MH
Miranda Hasty, BS
Saint Louis University School of Medicine
St. Louis, Missouri, United States
SJ
Sonia Jolly, BS
Saint Louis University School of Medicine
St. Louis, Missouri, United States
NC
Niraj R. Chavan, MD, MPH
Saint Louis University School of Medicine
St. Louis, Missouri, United States
TT
Tracy M. Tomlinson, MD, MPH
Saint Louis University School of Medicine
St. Louis, Missouri, United States