Paracervical block for labor analgesia: a brief historic review.

This historic review was written to clarify the known efficacy and side effects of paracervical blockade for labor analgesia. Although the popularity of the technique has diminished considerably, it continues to be used by some clinicians with ostensibly good results. The Cochrane Controlled Trials Register (CCTR;SR-PREG) and the electronic database MEDLINE were searched for studies reported in English to determine efficacy and side effects of paracervical block. Four randomized controlled studies specifically addressed paracervical block efficacy as assessed by parturients during labor with results of excellent or good analgesia among approximately 75%. Postparacervical block fetal bradycardia is the most significant side effect with a reported incidence ranging from 0% to approximately 40%. Overall, it appears that the incidence of postparacervical block fetal bradycardia is approximately 15%. However, the etiology of the observed fetal bradycardia remains unclear, and the incidence of adverse impact on fetal or neonatal outcome remains uncertain because there are too few trials with too few patients.