Abstract:

Objective To investigate the guidance of delivery mode and its effect on maternal and infant outcomes by intrapartum ultrasound in the prolongation of the second labor stage. Methods 262 parturients were selected as the study subjects，the angle of progression（AOP），head⁃perineum distance（HPD）and uterine expansion were detected by perineal ultrasound. The delivery time and delivery outcome were recorded，the predic⁃ tive value of AOP and HPD in natural delivery was analyzed，and the differences of delivery mode and delivery time of parturients with different ultrasonic characteristics were compared. Results Compared with natural delivery， AOP of midwifery and cesarean section group decreased significantly，and the proportion of non occipital anterior fetal orientation increased significantly（P < 0.05）. AOP and HPD have certain predictive value for vaginal sponta⁃ neous delivery（AUC > 0.7），and the best cutoff values are 124.77 ° and 4.62 cm，respectively. The natural delivery rate of women with AOP > 135 ° was significantly higher than that of women with AOP ≤ 135 °，and the natural delivery rate of women with HPD ≤ 4 cm was significantly higher than that of women with HPD > 4 cm（P < 0.001）. The delivery time of women with AOP > 135 ° was significantly lower than that of women with AOP ≤ 135 °（P < 0.05），and that of women with HPD ≤ 4 cm was significantly lower than that of women with HPD > 4 cm（P < 0.05）. Conclusions The measurement of AOP and HPD by intrapartum ultrasound in the second stage of labor can evaluate the mode of delivery and the length of delivery，which is helpful to improve the safety of mothers and infants during delivery. 

Key words:

intrapartum ultrasound, second stage of labor, mode of delivery, length of delivery