Background: This study aimed to compare the effects of peritoneal and subcutaneous injections of bupivacaine 0.5% on post-appendectomy pain and also the efficacy of local anaesthetic injection for postoperative pain relief in peritoneal inflammation with subcutaneous injection.

Materials and Methods: This randomized-clinical trial was conducted on 126 participants (age range, 15-45 years) underwent appendectomy for acute appendicitis in Kashan Shahid- Beheshti hospital. Participants were divided into three groups: bupivacaine (0.5%, ip), bupivacaine (0.5% s.c), and control (no injection). Pain intensity was evaluated using the visual analogue scale at 6, 12 and 24 hours after surgery.

Results: There was no significant difference among the three groups in age, sex, the duration of anesthesia and surgery. Pain intensity (6 h post-surgery) was significantly higher in the subcutaneous group than the peritoneal group, but no significant difference was seen between the two groups at 12 and 24 h post-surgery. Moreover, pain intensity in the peritoneal and subcutaneous groups was significantly lower than the control group at 6 and 12 h post-surgery (P<0.05). There was a significant difference between the peritoneal and subcutaneous groups as well as between the peritoneal and control groups required analgesics, but the difference was not significant between the subcutaneous and control groups.

Conclusion: Although both peritoneal and subcutaneous injections of bupivacaine can reduce postoperative pain in patients undergoing appendectomy, the peritoneal injection can significantly reduce the postoperative analgesic consumption.