A randomized controlled trial of liposomal bupivacaine for pain following obstetrical laceration

Abstract

Postpartum pain management is critical after vaginal delivery involving a second, third, or fourth degree laceration as patients heal from their repair. Uncontrolled postpartum pain can affect both the physical and mental recovery period, extend hospital stays, and increase the potential for serious adverse reactions with pain medications. In light of the opioid crisis and increase in dependency after utilization, finding alternatives for pain management after procedures is paramount. The need for a safe, effective, long-acting medication to treat postpartum and postoperative pain has reached a critical point in the current healthcare climate. To minimize pain after vaginal delivery, we assessed the effectiveness of liposomal bupivacaine vs plain bupivacaine injected into the perineum after second, third, or fourth degree lacerations. We hypothesized that the liposomal bupivacaine study group would have less vaginal pain, analgesic usage, and improved quality of life compared with the plain bupivacaine control group. This is a single-blinded randomized controlled trial with 120 subjects enrolled at Walter Reed National Military Medical Center, Bethesda, Maryland, from February 2018 to February 2019. After vaginal delivery and repair, study participants were randomized into 20-mL liposomal bupivacaine (study group) or 20-mL 0.25% plain bupivacaine (control group) injected into and around the perineal body bilaterally. On postpartum days 1, 3, and 7, pain scores and analgesics were recorded. Our primary outcome was vaginal pain score at postpartum day 3, analyzed with Wilcoxon rank-sum test. Our secondary outcomes included vaginal pain at postpartum days 1 and 7, pain with bowel movement, sleep disturbance, and pain's impact on activity, stress, and mood. Desired statistical power was achieved with 48 patients per group (total of 96 patients). A total of 60 patients were randomized to each group; 108 patients completed the study. Most patients (94%) had regional anesthesia. There was no statistically significant difference in the demographics between these groups. There were 25 obstetric anal sphincter injuries, equally distributed between the 2 groups (P>.99). There was no significant difference between vaginal pain scores at postpartum day 3 (control, 2 [1-3]; study, 2 [0-3]) (P=.63). This was also seen at postpartum day 1 (control, 2 [0-3]; study, 2 [0-3]) (P=.82) and postpartum day 7 (control, 1 [0-3]; study, 1 [0-2]) (P=.47). Cumulative pain scores for postpartum days 1, 3, and 7 failed to reach significance (study, 5 [3-8]; control, 6 [3-8]) (P=.83). Secondary analysis of pain with bowel movement and impact on sleep, activity, stress, and mood found no differences. Given that only 3 patients required outpatient opioids, there were insufficient data to calculate morphine equivalent differences. After obstetric lacerations, there is no proven benefit to lateral and intraperineal injection of liposomal bupivacaine over plain bupivacaine in postpartum vaginal pain scores, quality of life scores, or pain medication utilized. This may be due to low pain scores and opioid usage, both groups benefiting from the intervention, or ineffective perineal injection location.