The ‘occiput-spine angle’: a new sonographic index of fetal head deflexion during first stage of labor as predictor of course of labor and outcome

Abstract

abor is a physiologic process during which the products of conception (i.e. the fetus, membranes, umbilical cord, and placenta) are expelled outside of the uterus. Labor is achieved with changes in the biochemical connective tissue and with gradual effacement and dilatation of the uterine cervix as a result of rhythmic uterine contractions of sufficient frequency, intensity, and duration. Labor is divided into three stages that include cervical dilatation, fetal delivery and delivery of the placenta. The association between a prolonged second stage of labor and adverse maternal or neonatal outcome has been examined. The prolonged second stage is associated with adverse neonatal outcomes and increased maternal morbidity, including higher rate of operative vaginal delivery and cesarean delivery, postpartum hemorrhage, third- or fourth-degree perineal laceration. Deflexed cephalic presentations are an important cause of obstructed labor and account for one third of cesarean deliveries as the result of labor arrest. Three varieties of deflexed cephalic malpresentations traditionally are described according to the degree of head extension, including sinciput, brow, and face.