Predictive value of ultrasound assessed fetal head position in primiparous women with prolonged first stage of labor

Abstract

Objective: To examine how well ultrasound-assessed occipitoposterior (OP) position or high sagittal (HS) position in primiparous women with a prolonged first stage of labor predicts a vaginal delivery and the duration of labor.

Design: Prospective observational study.

Setting: Stavanger University Hospital, a secondary referral center in Norway.

Population: 105 primiparous women with prolonged first stage of labor.

Methods: Ultrasound assessment of fetal head position. Main outcome measures. Vaginal delivery vs. cesarean section and duration of labor.

Results: Twenty-five fetuses (24%) were delivered with cesarean section (CS), 45 (43%) had an operative vaginal delivery and 35 (33%) delivered spontaneously. Eleven (27%) of 41 fetuses in OP position at the time of inclusion were born in OP position. Ten (24%) of the 41 fetuses in OP position at inclusion were delivered with CS compared with 15/64 (23%) fetuses in other positions (p= 0.91). Twenty-eight fetuses were in sagittal position and 12 in HS position, assessed with ultrasound at the time of diagnosed prolonged labor. Seven (58%) of 12 in HS position delivered vaginally and five (42%) had a CS (p= 0.89). Time from inclusion to labor was not significant longer either for fetuses in OP compared with non-OP positions or for fetuses in HS compared with non-HS positions.

Conclusions: Most fetuses in OP or HS positions in the first stage of labor will rotate spontaneously and have a high probability of being delivered vaginally.