Use of ultrasound biparietal diameter in timing of repeat cesarean section.

The aim of the study was to evaluate the use of ultrasound biparietal diameter (BPD) in the timing of elective repeat cesarean section on a large indigent service. One hundred sixty-five patients were evaluated over 2 years. If the BPD was 9.3 cm or more at or later than 38 weeks' gestation, a repeat procedure was undertaken without further testing of fetal maturity. This occurred in 55% of the study group. None of these neonates developed hyaline membrane disease (HMD). The remainder of the study group either did not attain a BPD of 9.3 cm by term, were diabetic, or had other factors to determine timing of delivery. Of this group, 50% underwent amniocentesis for a lecithin:sphingomyelin ratio. Three patients had fetal bleeding, 1 had rupture of membranes, and 1 began labor following amniocentesis. All neonates were healthy except 1 who had mild HMD. That neonate had not reached 9.3 cm BPD. Ultrasound has allowed development of a management program for elective repeat cesarean section that is reliable, cost-effective, and beneficial to the mother and neonate.