Assessment of utero-cervical angle and cervical length as predictors for threatened preterm delivery in singleton pregnancies

Objectives: The aim of this study was to evaluate the relationship between the cervix and the threat of preterm labor in singleton pregnancies between gestational weeks less than 37 and greater than 37 weeks in correlation with utero-cervical angle (UCA) and cervical length (CL) measurements.

Materials and methods: We conducted a prospective cohort study with UCA and CL measurements in patients with threatened preterm labor (TPL). Primary outcome was differences in UCA and CL measurements in relationship to maternal characteristics and perinatal outcome between groups. Secondary outcome evaluated measurement results and influencing factors for delivery within 7 days, between 1 and 4 weeks and beyond 4 weeks.

Results: Overall 152 patients were divided into as study/preterm group (<37 weeks; n = 56) and the control/term group (≥37 weeks; n = 96). Mean gestational age at admission was similar in both groups (30.98 ± 2.83 vs. 30.36 ± 2.63 weeks, p = 0.149) with similar CL (33.9 ± 6.34 vs. 32.02 ± 8.88 mm, p = 0.132), but wider UCA in the preterm group (81.65 ± 16.81° vs. 99.21 ± 22.33°, p < 0.001). Multivariate logistic regression analysis for preterm delivery was significant for nulliparity and UCA measurement. The factor for delivering before 37 gestational weeks within 7 days was the gestational week at admission (p = 0.046). UCA and CL measurements were statistically significant for distinguishing patients for delivery within 7 days and beyond 4 weeks (p = 0.001 for CL and p = 0.0001 for UCA). NPV was found 92.5, 92.2, and 92.3 for UCA >105°, CL ≤30 mm, and Bishop score >3, respectively.

Conclusion: Combined measurement of TV UCA and CL represents stronger predictors for sPTB ultrasonographically, demonstrating the uterocervical sub-segment maturation before the active onset of labor.