Journal of perinatal medicine
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Paracervical block during labor following normal, uncomplicated pregnancy is occasionally accompanied by fetal bradycardia. To evaluate whether a paracervical block with bupivacaine causes changes in the vascular resistance of uteroplacental and umbilicoplacental blood flow, a total of 12 singleton, uncomplicated pregnancies in active labor at the end of pregnancy were included to this study. By using pulsed color Doppler ultrasound techniques the pulsatility indices were measured from both uterine and umbilical arteries before, one minute and 20 minutes after a paracervical block with bupivacaine. ⋯ When the fetal bradycardia ceased the pulsatility indices returned to the levels at the beginning of the study. Paracervical block with bupivacaine in normal pregnancies without signs of chronic or acute fetal distress does not change the vascular resistance in the uterine or umbilical arteries. If fetal bradycardia develops, it seems to be due to the direct effect of bupivacaine on the fetus, mainly on the umbilical vessels.