Post-Cerclage Cervical Length as Predictor of Preterm Birth

TOPLINE:

Post-cerclage cervical length (CL) was a significant predictor of spontaneous preterm birth (sPTB; < 34 weeks of gestation) in women who underwent cervical cerclage, predominantly outperforming pre-cerclage CL.

METHODOLOGY:

• Researchers in the UK conducted a retrospective cohort study at four preterm birth prevention clinics between January 2008 and March 2021 to assess the predictive value of CL measurements, both before and after cervical cerclage, for sPTB (< 34 weeks of gestation).
• They included 331 women who underwent cervical cerclage and had both pre- and post-cerclage CL measured per the standardised protocol using transvaginal ultrasound as recommended by the Cervical Length Education and Review program.
• The primary outcome was sPTB (< 34 weeks of gestation), assessed using multivariable logistic regression modelling (adjusting for pre- and post-cerclage CL, gestational age at cerclage, and direction of the CL change) and receiver operating characteristic (ROC) curves.

TAKEAWAY:

• Both pre-cerclage CL (area under the ROC curve [AUC], 0.635; 95% CI, 0.559-0.712) and post-cerclage CL (AUC, 0.677; 95% CI, 0.604-0.751) were predictors of sPTB.
• Adjusted models incorporating gestational age at cerclage demonstrated that both pre-cerclage CL (odds ratio [OR], 0.964; P = .018) and post-cerclage CL (OR, 0.940; P < .001) were significant predictors of sPTB.
• In a comparative model analysis, the effect of post-cerclage CL on sPTB was greater than that of pre-cerclage CL (OR, 0.943; P < .001 vs OR, 0.974; P = .058).
• Overall, sPTB was reported in 11.9% of women with history-indicated cerclage vs 24.3% of those with ultrasound-indicated cerclage and 36.8% of those with emergency cerclage (P = .003).

IN PRACTICE:

“Clinicians performing cervical cerclage should aim to maximize total CL when inserting cerclage and continue to monitor CL after cerclage insertion,” the authors wrote.

SOURCE:

This study was led by K. E. Mountain and S. Ng, March of Dimes Prematurity Research Centre at The Institute of Reproductive and Developmental Biology, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, England. It was published online on July 09, 2025, in Ultrasound in Obstetrics & Gynecology.

LIMITATIONS:

This study included only women who underwent cervical cerclage, limiting the use of pre-cerclage CL thresholds for decision-making guidance. Metrics related to the cerclage position within the cervical canal were not assessed. Additionally, the intervals between pre- and post-cerclage scans and cervical cerclage were not standardised.

DISCLOSURES:

This study was supported by the National Institute for Health and Care Research Imperial Biomedical Research Centre, London, and Tommy’s Charity, London, UK. The authors reported having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.