Fetal heart rate and uterine activity following paracervical block

Bupivacaine without adrenaline was used for paracervical block (PCB) anesthesia in 60 low-risk parturients in whom there were no signs of fetal asphyxia. In order to evaluate its effects on fetus and uterine activity, 30 patients were given a "high dose" of 50 mg Bupivacaine, an amide-type local anesthetic agent, while 30 patients were given a "low dose" of 25 mg. Continuous fetal heart rate (FHR) monitoring in both study groups revealed nine patients with typically post PCB bradycardia and five patients with moderate PHR depression. All of them were born with excellent Apgar score. Although a decrease in fetal heart rate following PCB was noted in both groups more significant reduction was associated with the high dose block (P less than 0.05). In 11 cases, FHR depression was clearly associated with increased uterine activity, while in another three cases it was not (P less than 0.005). Oxytocin administration during the block did not affect fetal heart rate or uterine activity. The results indicate that FHR depression following PCB using Bupivacaine is dose dependent, transient and not dangerous to a normal fetus. No adverse maternal effects were noted. It is suggested that fetal heart rate depression following PCB using Bupivacaine is related to increased uterine activity.