Sonoelastographic Assessment of the Uterine Cervix in the Prediction of Imminent Delivery in Singleton Nulliparous Women Near Term: A Prospective Cohort Study

Objectives To explore the role of newly developed software to assess cervical sonoelastography in predicting the onset of spontaneous delivery in singleton pregnancies at term and to compare its diagnostic performance with that provided by the cervical length (CL) and posterior cervical angle (PCA). Methods This work was a prospective study including nulliparous singleton pregnancies at gestational ages of 37 weeks to 38 weeks 6 days. The CL, PCA, hardness ratio (HR), and mean strain from the internal os and external os were obtained by a transvaginal ultrasound approach using semiautomatic software (E-Cervix; Samsung Medison Co, Ltd, Seoul, Korea). Multivariate logistic regression and area under the curve analyses were used to test the strength of the association and the diagnostic performance of the variables considered in predicting delivery within 7 days. Results A total of 398 women were included, and 24.6% delivered within 7 days. The CL was shorter (19.5 versus 2 7 mm;P= .0001), PCA narrower (99 degrees versus 102 degrees;P= .02) HR lower (35.3 versus 40.7;P= .0001), mean strain from the external os higher (0.41 versus 0.35;P= .0001), and mean strain from the internal os higher (0.38 versus 0.33;P= .0001) higher in women who delivered within 7 days from the assessment. At the multivariable logistic regression analysis, the CL (adjusted odds ratio, 1.307) and HR (adjusted odds ratio, 1.227) were the only variables independently associated with delivery within 1 week. A model combining the CL and HR showed an area under the curve of 0.873 in predicting delivery within 7 days, higher than that obtained by using the CL and HR singularly (P <= .0001). Conclusions The HR assessed by sonoelastography improves the efficacy of the CL in predicting imminent delivery in nulliparous women close to term.