Uterine and umbilical blood flow during cesarean section under epidural anesthesia

Umbilical and uterine blood flow velocity waveforms were studied in 22 women undergoing elective cesarean section under epidural anesthesia. The measurements were taken prior to initiation of anesthesia (baseline levels), after the appropriate level of anesthesia had been achieved (prior to the onset of surgery), and intraoperatively immediately prior to the uterine incision and after the delivery (uterine blood flow). Achievement of the therapeutic level of epidural anesthesia was not associated with altered umbilical and uterine blood flow. Intraoperatively, however, 2/3 of the women manifested increased resistance in the utero-fetal circuit, judging by the rise in S/D ratios. Under normal circumstances (absence of fetal distress and maternal complications prior to the cesarean section, adequate maternal hydration and oxygenation, etc.) these changes did not cause any neonatal compromise as evidenced by normal Apgar scores and freedom from complications during the neonatal period.