Background: Surgical site infiltration and transversus abdominis plane (TAP) blocks are commonly used to improve pain relief after lower abdominal surgery. This randomized, observer-blinded study was designed to compare the analgesic efficacy of TAP blocks with surgical site infiltration in patients undergoing open total abdominal hysterectomy via a Pfannenstiel incision.
Methods: Patients were randomized to receive either bilateral ultrasound-guided TAP blocks using bupivacaine 0.5% 20 mL on each side (n = 30) or surgical site infiltration with liposomal bupivacaine 266 mg diluted to 60 mL injected in the preperitoneal, subfascial, and subcutaneous planes (n = 30). The remaining aspects of the perioperative care were standardized. An investigator blinded to the group allocation documented pain scores at rest and with coughing, opioid requirements, nausea, vomiting, and rescue antiemetics in the postanesthesia care unit and at 2, 6, 12, 24, and 48 hours postoperatively. The primary outcome measure was pain scores on coughing at 6 hours postoperatively.
Results: One patient in each group was excluded from the analysis because of reoperation within 24 hours in the TAP block group and change of incision type in the infiltration group. The pain scores at rest and with coughing were significantly lower in the surgical site infiltration group at all postoperative time points (P < 0.0001) except at rest in the postanesthesia care unit. The opioid requirements between 24 and 48 hours were significantly lower in the infiltration group (P = 0.009). The nausea scores, occurrence of vomiting, and need for rescue antiemetics were similar.
Conclusions: Surgical site infiltration provided superior pain relief at rest and on coughing, as well as reduced opioid consumption for up to 48 hours. Future studies need to compare TAP blocks with liposomal bupivacaine with surgical site infiltration with liposomal bupivacaine.