Effects of preoperative ultrasound-guided transversus abdominis plane block on pain after laparoscopic surgery for colorectal cancer: a double-blind randomized controlled trial

Although laparoscopic colorectal surgery decreases postoperative pain and facilitates a speedier recovery compared with laparotomy, postoperative pain at trocar insertion sites remains a clinical concern. The objective of this study was to assess the effects of a preoperative ultrasound-guided transversus abdominis plane (TAP) block on pain after laparoscopic surgery for colorectal cancer. In total, 58 patients scheduled to undergo laparoscopic surgery following a diagnosis of colorectal cancer were included in this study. The patients were randomized into TAP and control groups; the TAP group patients received a preoperative ultrasound-guided bilateral TAP block with 0.5 mL/kg of 0.25 % bupivacaine, while the control patients received the block with an equal amount of saline. Pain on coughing and at rest was assessed during postanesthetic recovery (PAR; 1 h after surgery) and on postoperative days (PODs) 1 (24 h), 2 (48 h), and 3 (72 h) by an investigator blinded to group allocations using the numeric rating scale (NRS). The primary outcome was pain on coughing on postoperative day (POD) 1. Fifty-five patients were included in the final analysis, including 28 in the TAP and 27 in the control groups. The pain intensity on coughing and at rest during PAR and on PODs 1, 2, and 3 showed no significant differences between groups. Furthermore, there was no significant difference in postoperative opioid consumption, sedation scores, nausea scores at the four time points, complication rates, and length of hospital stay between groups. In colorectal cancer patients undergoing laparoscopic colorectal surgery, a TAP block did not offer enough benefit for clinical efficacy in terms of postoperative pain or analgesic consumption.