Cervical sliding sign and cervical funneling in the third trimester as predictors of spontaneous preterm birth in singleton pregnancy.

Background: Spontaneous preterm birth (sPTB) is a major cause of neonatal morbidity and mortality, and accurate prediction remains challenging. Sonographic transvaginal cervical length (CL) and uterocervical angle (UCA) are commonly used as general screening methods for predicting preterm birth. However, these methods are limited by the variability of reference values. Recently, cervical sliding sign (CSS) has been used as a sonographic marker for sPTB. However, few studies on its use in this context have been conducted. Therefore, the aim of this study was to ascertain the relationship between CSS in the third trimester and the risk of sPTB and to determine the possible additional risk if funneling is also present. Methods: This prospective cohort study included 168 singleton pregnancies in the third trimester (28 Results: Twenty-nine (17.26%) of the singleton pregnancies were CSS, and the area under the curve (AUC) for predicting preterm birth by CSS was 0.799 [95% confidence interval (CI): 0.713-0.885]. CSS had a specificity of 94.1%, a positive predictive value of 72.4%, and a negative predictive value of 92.1% for the prediction of sPTB. Cervical funneling was observed for 28 (16.67%) of the singleton pregnancies. The AUC for predicting preterm birth by cervical funneling was 0.648 (95% CI: 0.558-0.738). The AUC obtained by the combination of CSS and cervical funneling was 0.801 (95% CI: 0.710-0.892). The AUC for CSS was greater than that for funneling (0.799 Conclusions: CSS is a reliable and superior marker for predicting sPTB in singleton pregnancies as compared to cervical funneling. Although cervical funneling may also have some predictive value, CSS is more effective as a diagnostic tool for sPTB.