Intraoperative injection of bupivacaine‐adrenaline close to the fascia reduces morphine requirements after cesarean section: a randomized controlled trial

Objective. The purpose of this study was to investigate whether a single injection of bupivacaine with adrenaline close to the fascia could decrease opiate consumption and pain in patients undergoing cesarean section in spinal anesthesia. Design. Randomized double‐blind controlled study. Settings. Karolinska University Hospital, Huddinge, Sweden. Population. 260 women scheduled for elective cesarean section were enrolled in the study. Methods. The treatment group (n= 130) received 40 mL bupivacaine (2.5 mg/mL) with adrenaline (5 μg/mL) (Marcain® adrenalin) and the control group (n= 130) received 40 mL saline solution (0.9%), which was, in both groups, injected close to the fascia before closure of the wound. Main outcome measures. Morphine consumption and mean resting pain intensity numerical rating scale at 12 and 24 hours were the primary outcome variables. Other assessments for pain as well as mobilization parameters were considered secondary. Results. Morphine requirements were significantly less in the bupivacaine group, 19.0 mg/woman, compared with 24.0 mg/woman in the placebo group, during the first 12 postoperative hours. During this time period there was also a trend towards a difference between groups in mean pain intensity, but significant only during the first six hours. Over the whole first postoperative 24 hours, there were no differences in either morphine requirement or pain intensity between groups. Conclusions. A single injection of bupivacaine with adrenaline in the surgical wound decreases the need for morphine requirements for the first 12 postoperative hours and contributes to safe and effective pain management in women undergoing cesarean section.