Prediction of Successful Normal Vaginal Delivery by Ultrasonographic Measurement of Occiput-Spine Angle during First Stage of Labor

Abstract

Background: Most pregnancies end in spontaneous vaginal birth without the need for obstetric intervention. Nonetheless, some women do not progress past the second stage of labor and require surgical delivery. This study aimed to quantify the degree of fetal head deflection via the use of sonography during the first stage of labor and determine whether a parameter derived from ultrasound examination (the occiput-spine angle) has a relationship with the course and outcome of labor. Methods: This prospective randomized clinical trial was conducted on 140 women. All studied cases were subjected to the following: General examination with special emphasis, investigation [Blood group (ABO) and Rh] and antenatal ultrasound examination. Results: there was highly statistically significant higher mean value of Occiput-Spine Angle(o) in NVD group comparing to L.S.C.S group (p < 0.001). Area under the ROC curve (AUC) = 0.839 with SE 0.0388(95% Confidence interval 0.762 – 0.922. Z statistic =8.738, p < 0.001. Cutoff point>125o with sensitivity = 82.6%, specificity=84.6%, positive predictive value 73.6%, negative predictive value 96.1% and accuracy 84.3%. Conclusion: measurement of the occiput-spine angle, by sonography is feasible, reproducible and an objective tool to assess the degree of fetal head deflexion during labour and to predict the mode of delivery. Occiput-spine angle less than 125 degrees correlates with a significant increase in the rate of cesarean delivery, prolongation of the active and second stage of labor and increase incidence of maternal complications.