Paracervical block analgesia during labor

Maternal and fetal effects of low-dosage bupivacaine paracervical block

“…To reduce fetal hazards, a low dosage, superficial technique of PCB has been advised by BLOOM [2] and by JÄGERHORN [10] and was also used in our study. The success rate (76%) and the failure rate (12%) we found using that technique are of a similar order to that reported when using larger bupivacaine dosages [17]. The plasma levels of bupivacaine after low dosage (25 mg) administration in maternal, fetal and neonatal blood are lower than reported by HYMAN [8] (maternal 0.14, neonatal 0.08ug/ml) or by BEAZLEY [1] (1.07 and 0.10), who used 50 mg of bupivacaine at PCB.…”

“…No universal change in the mean uterine activity was noticed after PCB, but in five cases demonstrating bradycardia three showed a prompt increase in uterine contractions and in the baseline tone, which might at least partly explain the change in the FHR pattern. The etiopathology of FHR "changes in connection with PCB is obviously multifactorial [17]. According to our observations the most important factor in these mechanisms seems to be the rapid transplacental passage of the local anesthetic agent into the fetal circulation.…”

“…In spite of extensive clinical experience and research work, the usefulness and safety of PCB is still a matter of controversy [9,17]. To reduce fetal hazards, a low dosage, superficial technique of PCB has been advised by BLOOM [2] and by JÄGERHORN [10] and was also used in our study.…”

“…Vasoconstriction of the uterine arteries, hypertonus of the uterus, and the direct toxic effect of a local anesthetic agent on the fetus or a combination of the above have been presented as etiological factors [17]. To reduce fetal side-effects, a superficial and low dosage technique has been advised by BLOOM [2] and JÄGERHORN [10].…”

Human fetal transcutaneous pO2during paracervical block

“…In Sweden about 6000 women in labour are given paracervical block each year. An extensive survey of the literature failed to reveal any specific negative factors [4]. In a study of the biochemical changes of maternal and fetal blood during paracervical block fetal bradycardia was encountered in 50 per cent and was strongly correlated to maternal hyperventilation [2].…”