Correlation between cervical elastography parameters and time of the first stage of labor in late pregnancy by transvaginal ultrasound

Objective To investigate the correlations between the labor process and the elastography parameters, and to explore the correlations among the elastography parameters. Methods A total of 48 pregnant women in the late periods of pregnancy in Beijing Hospital from November 10, 2018 to January 30, 2019 were recruited prospectively. Elastography was performed to measure several elastographic parameters including the cervical length (CL), elasticity contrast index (ECI), hardness ratio (HR), internal orifice uterus(IOS) and external orifice uterus(EOS). They were followed up to delivery, and were divided into normal group and prolonged group according to the time duration of the first stage of labor. The correlation between the parameters and the time duration of the first stage of labor, as well as the relationships among the parameters were evaluated. Results Among the 48 pregnant women, 35 cases were delivered by the vagina, 13 by cesarean section, 4 of whom were due to the prolongation of the first stage of labor and the other 9 cases for other reasons. The values of the CL and HR in normal group were significantly lower than that in prolonged group (P=0.004, 0.02). The ECI in the normal group was significantly higher than that in the prolonged group (P=0.046). Both the IOS and EOS in the normal group were higher than those in prolonged group without no significant difference(P>0.05). For the 35 women who underwent cervical elasticity assessment before labor and finally delivered vaginally, the duration of the first stage of labor was negatively correlated with cervical ECI (r=-0.415, P 0.05). Conclusions The ECI of cervical tissue measured by cervical elastography can be used to semi-quantitatively evaluate the maturity of the cervix, it has potential value in predicting the labor duration and guiding clinical decision-making. Key words: Ultrasonography, transvaginal; Elastography; Time of the first labor; Late pregnancy