Is paracervical block safe and effective? A prospective study of its association with neonatal umbilical artery pH values

BACKGROUND. Paracervical blocks (PCBs) relieve labor pain, but reports of a ssociated complications have caused many physicians to question their safet y. METHODS. We designed a prospective observational study to examine the assoc iation between PCBs and umbilical artery hydrogen ion concentration (pH) va lues. A total of 261 healthy women in labor were recruited from a community hospital. Physicians used 1% lidocaine for the PCBs. We used multivariate linear regression to model predictors of umbilical artery pH at birth. RESULTS. Of the women studied, 238 (91%) received analgesia during labor (n albuphine, PCB, pudendal, caudal, or epidural). Of these, 126 (48%) receive d at least one PCB (191 were given), and 197 (76%) received at least one do se of nalbuphine (237 were given). Univariate analyses showed no significan t differences in mean I-minute Apgar scores, 5-minute Apgar scores, umbilic al artery pH, resuscitation with oxygen by mask, or length of newborn stay according to either PCB or nalbuphine exposure. Factors significantly assoc iated with lower umbilical artery pH in a linear regression analysis includ ed longer second stage of labor (-0.032 pH units for each I-hour increase; 95% confidence interval [CI], -.046 to -.018), pudendal block (-0.022; 95% CI, -.040 to -.004), intrauterine pressure catheter use (-0.029; 95% CI, -0 .053 to -.006), nuchal cord (-0.027; 95% CI, -.051 to -.004), and midforcep s delivery (-0.080; 95% CI, -.159 to.000). Increasing maternal age and indu ction with either artificial rupture of membranes or gel were associated wi th higher umbilical artery pH values. CONCLUSIONS. After adjusting for other variables, neither PCB nor nalbuphin e use were associated with umbilical artery pH at birth. PCBs using 1% lido caine injected superficially should be considered a safe and effective form of obstetric analgesia. PCBs may be especially useful for women giving bir th in hospitals where other obstetric anesthesia services are not readily a vailable.