The incidence and severity of shoulder dystocia correlates with a sonographic measurement of asymmetry in patients with diabetes.

The objective of this paper is to examine the relationship between fetal asymmetry measured sonographically and the incidence and severity of shoulder dystocia in diabetic patients. Ultrasound data were collected retrospectively from examinations of women with gestational and pregastational diabetes who delivered at University of California, Irvine Medical Center from 1993-1995. Sonographic fetal asymmetry was quantified by calculating the difference between the abdominal diameter and the biparietal diameter in centimeters (AD-BPD). The residual AD-BPD was a patient's actual AD-BPD at the time of the ultrasound minus the mean AD-BPD obtained in our population at the patient's gestational age. The correlations between fetal asymmetry and the incidence and severity of shoulder dystocia were assessed using an analysis of variance as well as a logistic regression analysis. Mild shoulder dystocia was defined as a delivery requiring McRobert's maneuver and/or suprapubic pressure, while severe shoulder dystocia was assessed when delivery of the posterior arm with Wood's corkscrew maneuver was required. One hundred twenty-three women met the inclusion criteria for the study. Dividing the cohort into three groups based on AD-BPD residual values resulted in the following AD-BPD residual ranges and incidences of shoulder dystocia: Group I, -1.80 to -0.32 cm (9.8%), Group II, -0.31 to 0.32 cm (19.5%), and Group III .33 to 2.0 cm (34.1%), (p <0.03). The residual AD-BPD difference correlated with the incidence of shoulder dystocia after controlling for maternal age, weight, parity, birth weight, and the gestational age at ultrasound (P <0.03). Similar results were found with regards to dystocia severity as the mean residual AD-BPD difference between those with no dystocia, mild dystocia, and severe shoulder dystocia was -0.09, 0.23, and 0.46 cm, respectively, (p <0.006). The residual AD-BPD correlated with the severity of shoulder dystocia after controlling for the above-mentioned confounding variables (p <0.05) in a regression analysis. There is a direct correlation in diabetic patients between the level of fetal truncal asymmetry measured sonographically and the incidence and severity of shoulder dystocia.