Objective To investigate the predictive value of labor progress angle (AOP), fetal head descent distance (HPD) and their change rates in the outcome of vaginal trial of cesarean scar uterus.

Methods A total of 170 pregnant women who underwent vaginal trial production of scar uterus after cesarean section were selected as study subjects, and were divided into successful group and failed group based on the trial production outcomes. Advanced oxidation processes (AOP) and head-perineum distance (HPD) were measured by ultrasound during the active phase of the first stage of labor when the cervix dilated to 4 cm and at 1 hour after the cervix dilated to 4 cm, respectively. The AOP change rate and HPD change rate after 1 hour of progress were calculated. The receiver operating characteristic (ROC) curve was used to analyze the predictive efficacy of AOP, HPD and their change rates in the outcome of vaginal trial production of scar uterus after cesarean section. Delong test was used to compare the differences in area under curves (AUCs).

Results Among 170 pregnant women with scarred uterus after cesarean section who were pregnant again, 139 cases (success group) were succeed in transvaginal delivery, while 31 cases failed trial delivery, and transferred to cesarean section (failure group). The AOP of the successful group was significantly larger than that of the failed group when the cervix was opened to 4 cm, and the HPD was significantly shorter than that of the failure group (P < 0.05). The AOP change rate and the change rate of HPD of the successful group were significantly higher than that of the failed group when the cervix dilated to 4 cm and at 1 hour (P < 0.05). The AUC of AOP and HPD in predicting the outcome of vaginal trial delivery of scar uterus after cesarean section were 0.846 and 0.812 respectively, and AUC predicted jointly by AOP and HPD showed no significant differences compared with AUC predicted separately (P>0.05). The AUC of the change rate of AOP and HPD in predicting the outcome of vaginal trial delivery of scarred uterus after cesarean section was 0.899 and 0.852 respectively, and the combined prediction of AOP change rate and HPD change rate had a higher AUC value than the AUC predicted separately. Its AUC value was higher than that of AOP combined with HPD (P < 0.05).

Conclusion The AOP, HPD and their change rates when the uterine orifice expands to 4 cm in the active phase of the first stage of labor have predictive value for the outcome of vaginal trial production of scarred uterus after cesarean section.