Dystocia in late labor: determining fetal position by clinical and ultrasonic techniques.

A failure of adequate progression during late labor occurs often and may prohibit an accurate determination of the fetal head position from scalp edema or caput formation. This investigation was undertaken to determine whether ultrasonic evaluation could confirm or correct the digital examination impressions of the fetal head position. Eighty-six attempted vaginal deliveries had recent evidence for arrested cervical dilation after 7 cm or more. An occiput transverse position in 24 (28%) cases was diagnosed accurately, with the need for additional ultrasonic information only in the presence of scalp edema. Distinguishing between a persistent occiput posterior (15 cases, 17%) or anterior (47 cases, 55%) position was often inexact by palpation alone. Combined clinical and ultrasonic impressions allowed for a significantly more precise diagnosis. Ultrasonic imaging allowed for more security while waiting, more confidence with midforceps application, or a prompter decision for cesarean section, depending on the head position.