Transversus abdominis plane block does not improve early or late pain outcomes after Cesarean delivery: a randomized controlled trial

Cesarean delivery is a common surgical procedure with anticipated substantial postoperative pain. The addition of a transversus abdominis plane block (TAPB) to a multimodal analgesic regimen that includes intrathecal morphine may provide improved early pain outcomes and decrease the risk of chronic post-surgical pain. The purpose of this research was to assess the ability of an ultrasound-guided TAPB with low-dose ropivacaine to decrease early postoperative pain, opioid consumption, and risk of developing persistent pain when compared with a placebo block. Eighty-three women were randomly assigned to either a treatment (0.25% ropivacaine) or control group (0.9% saline) in this double-blind trial, and 74 women were included in the final analysis. Ultrasound-guided TAPBs were performed with an injection of 20 mL of study solution per side. The primary outcome measures of this study were: pain at rest and pain after movement measured with a numeric rating scale, results of the Quality of Recovery-40 (QoR-40) questionnaire, and opioid consumption at 24 hr. These were used with an a priori sample size calculation to detect a 30% reduction in pain scores, a 10% improvement in QoR-40 score, and a 50% reduction in opioid consumption. Health quality and physical functioning were assessed using the Short Form 36 (SF-36A (R)) Health Survey at 30 days and six months. Assessment at 24 hr after Cesarean delivery revealed no clinically important differences between groups in postoperative pain, QoR-40, or opioid consumption. There were no clinically important differences between groups regarding measures of nausea, pruritus, vomiting, urine retention (2, 24, and 48 hr postoperatively), 24-hr QoR-40 sub-dimensions, or the SF-36 Health Survey (30 days and six months postoperatively). Ultrasound-guided TAPB did not improve postoperative pain, quality of recovery, or opioid consumption 24 hr following surgery. Similar health and functioning (SF-36) at 30 days and six months were reported by both groups. This trial was registered at ClinicalTrials.gov number: NCT01261637.