Macrosomia and Shoulder Dystocia Prediction using Prenatal Ultrasound Measurement

Yoon, Sung Jun; Kang, Kue Hyun; Park, Hyoung Moo; Hur, Min; Lim, In Seok

Abstract

OBJECTIVE
To determine if birth weight greater than 4000gm can be predicted by ultrasound measurement of abdominal circumference(AC) and if shoulder dystocia in macrosomic infants can be predicted by ultrasound measurement of the difference between the abdominal diameter(AD) and biparietal diameter(BPD).
METHODS
A Retrospective study was performed of births occuring from March, 1998 to August, 1999 at department of Obstetrics and Gynecology, College of Medicine, Chung-Ang University. Among neonates of birth weight greater than 4000 gm, 50 cases in that ultrasound examination was done within 2 weeks before delivery were selected for macrosomic group and 50 cases were selected for control group during the same period, among neonate of birth weight from 3100gm to 3900gm. RESULTS: 1) Normal spontaneous vaginal delivery(NSVD) was 41 cases in control group and 30 cases in macrosomic group. Among NSVD, shoulder dystocia was 1 case in 41 cases of control group and was 7 cases in 30 cases of macrosomic group. 2) On ultrasound measurement, 6 cases had AC greater than 35 cm in control group and 45 cases in macrosomic group. Among 30 cases in NSVD was done in macrosomic group, difference between AD and BPD was 2.9 0.271 cm when shoulder dystocia was existed and was 2.1 0.409 cm when shoulder dystocia was not existed. Between the two groups, statistically significant difference was detected. 3) When AC(cutoff value of 35cm) was used for screening of macrosomia, sensitivity for macrosomia was 88.2% and specificity was 89.8% and when AD-BPD difference(cutoff value of 2.6cm) was used for prediction of shoulder dystocia, sensitivity for shoulder dystocia was 66.6% and specificity was 95.2%. CONCLUSIONS: In prenatal ultrasound measurement, AC measurement at third trimester of pregnancy will be a valuable indicator for macrosomia screening. The AD-BPD difference of shoulder dystocia group was greater than uncomplicated group in macrosomia and the AD-BPD difference cutoff value of 2.6cm was significant value statistically.