BACKGROUND: The transversus abdominis plane (TAP) block is a novel approach for blocking the abdominal wall neural afferents via the bilateral lumbar triangles of Petit. We evaluated its analgesic efficacy in patients during the first 24 postoperative hours after abdominal surgery, in a randomized, controlled, double-blind clinical trial.METHODS: Thirty-two adults undergoing large bowel resection via a midline abdominal incision were randomized to receive standard care, including patient-controlled morphine analgesia and regular nonsteroidal antiinflammatory drugs and acetaminophen (n = 16), or to undergo TAP block (n = 16) in addition to standard care (n = 16). After induction of anesthesia, 20 mL of 0.375% levobupivacaine was deposited into the transversus abdominis neuro-fascial plane via the bilateral lumbar triangles of Petit. Each patient was assessed by a blinded investigator in the postanesthesia care unit and at 2, 4, 6, and 24 h postoperatively.RESULTS: The TAP block reduced visual analog scale pain scores (TAP versus control, mean +/- SD) on emergence (1 +/- 1.4 vs 6.6 +/- 2.8, P < 0.05), and at all postoperative time points, including at 24 h (1.7 +/- 1.7 vs 3.1 +/- 1.5, P < 0.05). Morphine requirements in the first 24 postoperative hours were also reduced (21.9 +/- 8.9 mg vs 80.4 +/- 19.2 mg, P < 0.05). There were no complications attributable to the TAP block. All TAP patients reported high levels of satisfaction with their postoperative analgesic regimen.CONCLUSIONS: The TAP block provided highly effective postoperative analgesia in the first 24 postoperative hours after major abdominal surgery.