Cervical dilation staging and early preterm birth risk after examination-indicated cerclage: a retrospective cohort study with the International Collaborative for Cerclage Longitudinal Evaluation and Research

Abstract

Background: Preterm birth is a leading cause of neonatal morbidity and mortality. The risks of preterm birth, especially early preterm birth, and pregnancy loss are significantly increased in patients with premature cervical dilation. An intervention to reduce the risk of preterm birth in this setting is cerclage. However, considering the limited data evaluating these differences, counseling on the risk of preterm birth and neonatal outcomes based on different cervical examination findings at the time of cerclage placement is difficult.

Objective: This study aimed to determine how the cervical examination staging criteria of Roman and colleagues before placement of examination-indicated cerclage were associated with the risk of very early preterm birth at <28 weeks of gestation.

Study design: This was a retrospective analysis using the International Collaborative for Cerclage Longitudinal Evaluation and Research database, a multicenter international retrospective database of singleton pregnancies that received a cerclage. Our study included participants who received a physical examination-indicated cerclage. The predictor of interest was cervical stage assessed preoperatively, evaluated as an ordinal variable with progressive severity indicated by advancing stage: stage 3 (visually closed, manually dilated with palpable membranes), stage 4A (visually dilated, membranes seen but not to the external os), stage 4B (visually dilated, membranes at the external os), and stage 4C (visually dilated, membranes past the external os). The primary outcome was preterm birth at <28 weeks of gestation. The secondary outcomes included preterm birth at <34 weeks of gestation, preterm birth at <37 weeks of gestation, and latency from cerclage placement to delivery. Multivariate analysis was performed, adjusting for study site, previous preterm birth, gestational age at cerclage placement, use of perioperative antibiotics or indomethacin, and progesterone use after cerclage placement.

Results: The analysis included 81 patients who had placement of a physical examination-indicated cerclage and met the inclusion criteria. The numbers of patients with stages 3, 4A, 4B, and 4C were 17, 27, 25, and 12, respectively. Multivariate analysis revealed that advanced cervical stage was significantly associated with preterm birth at <28 weeks of gestation (overall P value of .003). The rates of preterm birth at <28 weeks of gestation by stage were 11.7% for stage 3, 25.9% for stage 4A, 44.0% for stage 4B, and 75.0% for stage 4C. The adjusted odds ratios for preterm birth by progressive cervical stage compared with stage 3 were 2.4 (95% confidence interval, 0.31-19.25; P=.40) for stage 4A, 8.7 (95% confidence interval, 1.2-63.9; P=.03) for stage 4B, and 43.73 (95% confidence interval, 3.3-572.2; P=.004) for stage 4C. Latency to delivery after cerclage decreased with increasing Roman stage, although this was only statistically significant for stage 4C.

Conclusion: Cervical staging based on dilation and degree of membrane prolapse helps risk stratify patients presenting with advanced cervical dilation with successful cerclage placement and may be a useful tool for counseling and management.

Keywords: cerclage; cervical cerclage staging criteria; cervical insufficiency; physical examination–indicated cerclage; preterm birth.