Can Intrapartum Ultrasound Assessment of Fetal Spine and Head Position Predict Persistent Occiput Posterior Position at Delivery?

Abstract

Objective: To investigate the predictive value of fetal spine and head position in the first and second stages of labour measured by intrapartum ultrasound for persistent occiput posterior position at delivery in Chinese women in Hong Kong.
Methods: This was a prospective cohort study. A total of 100 women with a singleton term pregnancy in cephalic presentation underwent transabdominal ultrasound during the first or second stage of labour to measure fetal spine and head position. Fetal head position at birth was also recorded.
Results: Ninety-four women were included, of whom 35 and 51 were assessed in the first or second stage of labour, respectively, and eight were assessed at both stages. At the first stage, nine out of 43 fetuses were in the occiput posterior position with eight having a posterior spine position; one baby was delivered in the occiput posterior position. At the second stage, nine out of 59 fetuses were in occiput posterior position, with seven having a posterior spine position. Two (28.5%) fetuses with both spine and occiput at posterior position were delivered in that position. As the majority of fetuses with occiput posterior position in the first stage were delivered in a non–occiput posterior position, data obtained at the second stage were used for analysis. The positive predictive value of fetal spine and head position was 25% and 22.2%, respectively, whereas negative predictive value of both positions was 98%.

Conclusions: Fetal spine and head position assessed using ultrasound during the second stage of labour may be helpful in cases of persistent occiput posterior position at delivery and thus allow manoeuvres to be performed to facilitate delivery.