Journal of the Medical Association of Thailand Vol 101, No 9:SEPTEMBER 2018 0125-2208 101 9 2018 Sep Head Perineal Distance and Angle of Progression to Predict Caesarean Delivery due to Labor Dystocia in Term Pregnancy with Active Phase of Labor 1157-62 EN Teenat Kanjanasignh Wiyada Luangdansakul Original Article To evaluate the predictive value of head perineal distance [HPD] and angle of progression [AOP] measured by transperineal ultrasound to predict of caesarean delivery due to labor dystocia in term pregnancy with active phase of labor. The present report was a prospective study conducted at Bhumibol Aduyadej Hospital between January and December 2016. Term singleton pregnancy in cephalic presentation were enrolled when they entered the active phase of labor and abnormal partograph were not present during the time of enrollment. HPD and AOP were measured and then all participants received standard labor management. Data of transperineal ultrasound and obstetric outcome were obtained and analyzed to predict caesarean delivery due to labor dystocia. Among 400 participants enrolled in the present study, sixty-three cases (15.75%) underwent caesarean delivery due to labor dystocia. From the receiver operating characteristics curve, area under the ROC curve of HPD and AOP to predict cesarean delivery were 66% (95% CI, 59% to 73%) and 74% (95% CI, 68% to 80%), respectively. The cut-off point of HPD was 5.67 cm or greater, corresponding to a sensitivity of 88.69%, and a specificity of 34.42%. For AOP, 96 degrees or less, corresponded to a sensitivity of 71.42%, a specificity of 67.46%. According to binary logistic regression, AOP was associated with caesarean delivery due to labor dystocia significantly and independently [adjusted OR 4.46 (95% CI 2.06 to 9.21)], while the HPD was not [adjusted OR 1.80 (95% CI 0.72 to 4.51)]. AOP of 96 degrees or less can be used as a screening tool for labor dystocia in term pregnancy while the HPD cannot. Labor dystocia Head perineal distance Angle of progression