Objective: To evaluate the value of transvaginal ultrasound parameters before and after cerclage in twins in predicting spontaneous preterm birth (sPTB) before 28+0 weeks.
Methods: We retrospectively studied the medical records of twin-pregnant women who underwent ultrasound-indicated cerclage between January 2016 and February 2022 at our hospital. Recorded transvaginal ultrasound images before and after cerclage were reassessed for cervical length (CL), uterocervical angle (UCA), funneling, and sludge. Multivariate logistic and Cox regression analyses were performed to identify the independent risk factors associated with sPTB before 28 weeks.
Results: A total of 69 women were included. Among them, 17 women (24.64%) delivered before 28 weeks of age. Regression analysis revealed a significant association of post-cerclage CL, UCA, white blood cell (WBC) count, and gestational age (GA) at cerclage with sPTB before 28 weeks. The area under the curve of these predictors was 0.938 (95% confidence interval, 0.882-0.994; p < .001), with a sensitivity of 88.2%, specificity of 92.3%, positive predictive value of 78.9%, and negative predictive value of 96.0%. Cox analysis showed that post-cerclage UCA was an independent risk factor affecting the cerclage-to-delivery interval (hazard ratios, 1.026; 95% confidence interval (CI), 1.004-1.048; p = .019).
Conclusions: The combination of post-cerclage CL, UCA, WBC count, and GA at cerclage showed good performance in predicting sPTB at <28 weeks in twin pregnancy. Post-cerclage UCA is also associated with pregnancy latency. We found that post-cerclage cervical ultrasound may be useful to predict preterm birth before 28 weeks in twins who undergo ultrasound-indicated cerclage.
Keywords: Ultrasound-indicated cerclage; cervical length; spontaneous preterm birth; twin pregnancy; uterocervical angle.