To analyze the application value of intrapartum ultrasound in evaluating the progression of labor.

A total of 120 pregnant women who underwent vaginal trial labor at the obstetrics department of Xi'an Daxing Hospital from March 2020 to June 2020 were selected. Cervical dilation size and fetal head angle of progression (AoP) and fetal head perineum distance (HPD) were measured by ultrasound. Experienced midwives performed vaginal palpation to determine the size of cervical dilation and the minimum point of fetal exposure. The data remained mutually blinded during the evaluation by both groups. Pearson correlation analysis was performed to determine the correlation between cervical dilation and the size of vaginal palpation, as well as between AoP and HPD and the lowest point of fetal first exposure. The performance of AoP and HPD in predicting natural delivery was assessed using the receiver operating characteristic (ROC) curve.

Vaginal palpation of the cervix was positively associated with cervical size measured by ultrasound (r=0.904, P＜0.001). As the fetal head position decreased, AoP gradually increased and HPD gradually decreased. Using a cut-off value of 96.5°, the area under the ROC curve of the AoP for predicting spontaneous delivery was 0.699, with a sensitivity of 75% and specificity of 60%. Using a cut-off value of 36.5 mm, the area under the ROC curve of the HPD for predicting natural birth was 0.624, with a sensitivity of 48% and specificity of 80%.

Ultrasonic assessment of cervical dilation is basically in line with the vaginal palpation results. The intrapartum ultrasound parameters AoP and HPD can be used to assess the position of fetal head descent, which is feasible to predict the mode of delivery.