Objective: To assess the accuracy and reliability of cervico-portio (CP) length estimated using the Cervilenz™ compared with transvaginal ultrasound (TVU) cervical-length in women at high and low risk of spontaneous preterm birth (SPTB).
Methods: Cervical-length was assessed longitudinally across gestation utilizing CP-length measured with Cervilenz™ and TVU. Altman-Bland plots were used to compare Cervilenz™ and TVU cervical-length. Regression analysis was used to assess the effect of gestational age, previous SPTB and previous cervical surgery on Cervilenz™ accuracy. Receiver operator curves (ROC) were utilized to determine the CP-length measured by Cervilenz™ with the optimum sensitivity and specificity for predicting TVU cervical-length <25 mm. ROCs were utilised to compare the ability of Cervilenz™ with TVU to predict SPTB.
Results: Seventy-five women were recruited (low risk N = 57, high risk N = 18). A total of 259 TVU and 253 Cervilenz™ measurements were taken with up to six measures in each woman. The Cervilenz™ CP-length was on average 9 mm shorter than TVU measured cervical-length. The difference decreased with advancing gestational age (p < 0.001). Cervilenz™ CP-length <24 mm was a good predictor of TVU cervical-length <25 mm (area under the curve (AUC) = 0.867). After accounting for baseline Cervilenz™ measurements, the relationship between Cervilenz™ and TVU measures was not influenced by pregnancy risk status. There were no significant differences between Cervilenz™ (AUC = 0.716) and TVU (AUC = 0.706) in predicting SPTB.
Conclusion: Cervilenz™ is an effective tool for screening cervical-length in comparison to TVU. Cervilenz™ may facilitate greater access to cervical-length measurement and assessment of risk of preterm birth.