Objective: To compare pain after robotic-assisted laparoscopic hysterectomy when giving preoperative oral compared with intravenous acetaminophen.
Methods: This double-blind randomized trial included women undergoing robotic-assisted laparoscopic hysterectomy for benign indications. Participants received either acetaminophen 1 g orally then normal saline 100 mL intravenously before surgery, or a placebo orally then acetaminophen 1 g intravenously. The primary outcome measured was difference in pain between the groups 2 hours postoperatively. A sample size of 74 participants (37/group) was needed to achieve 80% power to detect noninferiority using a one-sided, two-sample t-test with an alpha of 0.025 and a noninferiority margin of 10 mm.
Results: From April 2016 through August 2017, 77 patients were enrolled, with 75 participants included in the final analysis. Characteristics were similar between groups. No difference in average pain score was noted 2 hours after surgery, nor at any of the measured time points. Average scores for the oral and intravenous group, respectively, at 2 hours were 35 and 36 mm (P=.86), at 4 hours 36 and 37 mm (P=.96), and at 24 hours 35 and 36 mm (P=.79). Thirty-eight percent of participants in the oral group and 19% of participants in the intravenous group experienced nausea (P=.12). The oral group used 9.7 morphine equivalents in the recovery room, and the intravenous group used 9.5 morphine equivalents (P=.9). The oral group requested analgesia in 45 minutes on average, and the intravenous group requested analgesia in 43 minutes (P=.79).
Conclusion: No difference in pain was observed 2 hours postoperatively when comparing preoperative administration of oral compared with intravenous acetaminophen. Given the ease of administration and lower cost of oral dosing, this study supports the oral route as part of the enhanced recovery after surgery protocol for minimally invasive gynecologic surgery.
Clinical trial registration: ClinicalTrials.gov, NCT03391284.