A Randomized, Double-Blind, Placebo-Controlled Trial of Epidural Morphine Analgesia After Vaginal Delivery

Abstract

Pain after vaginal delivery can interfere with the activities of daily living. We hypothesized that epidural medication administered after delivery would be of benefit for acute postpartum pain management. The objective of this study was to assess whether epidural morphine after vaginal delivery would reduce the analgesic requirements for perineal pain. This randomized, double-blind, placebo-controlled trial included 228 parturients who received epidural morphine, 2.5 mg, or epidural saline within 1 h of delivery. The primary outcome was the proportion of women who received additional analgesics in the first 24 h postpartum. We also evaluated the time to first request for analgesia, pain and satisfaction scores, and the incidence of side effects due to epidural morphine. The majority of the 228 women participating in the study were Caucasian, primiparous patients >30 yr old. The proportion of women requiring additional analgesics was less among those who received epidural morphine (8 of 113; 7%) compared with saline (37 of 115; 32%), regardless of the degree of perineal trauma (RR = 0.22, 95% CI: 0.12-0.41). The relative risk reduction in receiving additional analgesics for primiparous patients receiving epidural morphine compared with saline was 0.25 (95% confidence interval [CI]: 0.13-0.49) and for multiparous women was 0.12 (95% CI: 0.02-0.63). The time to first request for analgesics was later for those who received morphine (mean 22.9 h, 95% CI: 22.2-23.7) compared with saline (mean 18.9 h, 95% CI: 17.4-20.4) (P < 0.0001). The side-effect incidence (pruritus, nausea and vomiting, and sedation) was not different between the 2 groups. There was a 78% reduction in analgesic requirements in women given epidural morphine after vaginal delivery compared with placebo for both primiparous and multiparous patients. Women who receive epidural labor analgesia for vaginal deliveries and stay in the hospital for 24 h after delivery may benefit from postpartum administration of epidural morphine.