Radiographic measures of the mid pelvis to predict cesarean delivery.

Abstract

The purpose of this study was to determine whether x-ray measures of the mid pelvis can be used to predict cesarean delivery. Women were enrolled prospectively; x-ray pelvimetry was performed after delivery; the readers were blinded to the outcome. Groups were determined by mid pelvis measures (transverse diameter, anteroposterior diameter, and circumference ≤ 10th percentile. The primary outcome was cesarean delivery. Univariable, stratified, and multivariable analyses were performed to estimate the effect of mid pelvis measures on cesarean delivery. Receiver operator characteristics curves were created to estimate the predictive value of mid pelvis measures of cesarean delivery. Four hundred twenty-six women were included. Subjects with anteroposterior diameter or circumference ≤ 10th percentile were at greater risk of cesarean delivery (risk ratio for anteroposterior diameter, 4.8; 95% confidence interval, 3.9-5.8; risk ratio for circumference ≤ 10th percentile, 3.8; 95% confidence interval, 3.1-4.8). Transverse diameter ≤ 10th percentile was not associated with an increased risk of cesarean delivery. The area under the receiver operator characteristics curves for anteroposterior diameter, circumference ≤ 10th percentile, and transverse diameter were 0.88, 0.85, and 0.69, respectively (P < .01). Simple radiographic measures of the mid pelvis on x-ray can provide a useful adjunct to clinical information in the determination of who should attempt a vaginal delivery.