The Analgesic Efficacy of Postoperative Bilateral, Ultrasound-Guided, Posterior Transversus Abdominis Plane Block for Laparoscopic Colorectal Cancer Surgery: A Randomized, Prospective, Controlled Study

Background: The study aimed to observe whether a postoperative bilateral, ultrasound-guided, posterior transversus abdominis plane block offers more benefits than placebo in patients undergoing elective laparoscopic colorectal cancer surgery in the enhanced recovery after surgery program.Methods: Patients scheduled to undergo elective laparoscopic surgery following the diagnosis of colorectal cancer were included in this study and randomized into Group TAP and Group Control. The patients received a postoperative bilateral, ultrasound-guided, posterior transversus abdominis plane block either 20 mL of 0.5% ropivacaine (Group TAP) per side or an equivalent volume of normal saline (Group Control). The primary outcome was the cumulative consumption of rescue tramadol within 24 h after the surgery. Secondary endpoints included numerical rating scale (NRS) pain scores at rest and movement at 2, 4, 6, 12, 24, 36, 48, and 72 h. The related side effects, time to the first request for rescue tramadol, patient satisfaction on postoperative analgesia, time to the intestinal function return, time to mobilization, and the length of hospital stay were recorded.Results: In total, 92 patients were randomized, and 82 completed the trial. The posterior TAP block reduced numeric rating scale pain scores at rest and movement at 2, 4, 6, 12, and 24 h after surgery but showed similar scores at 48 or 72 h. The total rescue tramadol requirement within the first 24 h reduced in Group TAP. A higher level of satisfaction with postoperative analgesia was observed in Group TAP on day 1 which was similar on days 2 and 3, compared with the Group Control. There were no complications due to the TAP block. A few incidences of opioids related side effects and a lower percentage of patients needing rescue tramadol analgesia within 24 h were observed in Group TAP. The time to the first request for rescue analgesia was prolonged, and the time to mobilization and flatus was reduced with a shorter hospital stay in Group TAP.Conclusions: A postoperative bilateral, ultrasound-guided, posterior transversus abdominis plane block resulted in better pain relief and a faster recovery in patients undergoing laparoscopic colorectal cancer surgery, without adverse effects. Trial registration: The study was registered at http://www.chictr.org.cn (ChiCTR-IPR-17012650，12, Sep 2017).