ABSTRACT
Artificial rupture of fetal amnionic membranes is frequently performed in normally
progressing spontaneous labor, although the maternal and fetal effects of the procedure
have not been clearly defined. The effect of elective amniotomy on placental impedance
to blood flow in the umbilical artery and arcuate branches of the uterine artery was
determined by analysis of blood flow velocity waveforms (FVWs) recorded with continuous
wave Doppler ultrasound in 15 pregnant women at term. All patients were in spontaneous,
normally progressing labor after an uneventful pregnancy. Electronic fetal heart rate
monitoring and real-time ultrasound examination of the fetuses were unremarkable.
FVWs were obtained immediately before and after amniotomy. Fourteen patients progressed
to spontaneous vaginal delivery, and one patient underwent repeat cesarean section
for arrest of dilation in the active phase of labor. No maternal, fetal, or neonatal
complications were recorded. Calculated mean systolic/diastolic ratios of FVWs obtained
before and after amniotomy were compared by means of Wilcoxon's signed rank test,
and no significant differences were found. We conclude that early elective amniotomy
exerts no demonstrable deleterious effect on impedance to uteropla-cental or fetoplacental
blood flow in healthy women at term.
