Correlation of increased fetal asymmetry with shoulder dystocia in the nondiabetic woman with suspected macrosomia.
OBJECTIVE
To determine if the sonographic difference of > or = 2.6 cm between the fetal abdominal diameter (AD) and biparietal diameter (BPD), a proxy for fetal asymmetry, has an association with shoulder dystocia in nondiabetic women with suspected macrosomia.


METHODS
A retrospective cohort study was performed in 3 Southern California tertiary care hospitals. We identified patients in whom sonographic evaluation after 36 weeks' gestation demonstrated an estimated fetal weight > 4,000 g. Additional prenatal and delivery information was obtained from hospital records.


RESULTS
We identified 159 subjects who met ultrasound criteria and underwent a vaginal delivery. The mean AD-BPD difference in the shoulder dystocia group was significantly greater than in the group without shoulder dystocia (2.76 +/- 0.59 vs. 2.37 +/- 0.56, p = 0.001). The adjusted OR of shoulder dystocia in the group with an AD-BPD difference > or = 2.6 was 3.67 (95% CI, 1.44-9.36).


CONCLUSIONS
Significant discordance between the fetal head and abdomen appears to be associated with an increased rate of shoulder dystocia in a nondiabetic population with suspected macrosomia.
Rajan
Priya V
PV
Department of Obstetrics and Gynecology, University of California, Irvine, Orange, California 92868, USA. mfm@uci.edu
Chung
Judith H
JH
Porto
Manuel
M
Wing
Deborah A
DA
D000328:Adult; D002508:Cephalometry; D004420:Dystocia / Q000000981:diagnostic imaging*; D005260:Female; D005320:Fetal Macrosomia / Q000000981:diagnostic imaging*; D006801:Humans; D016017:Odds Ratio; D011247:Pregnancy; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal