Impact of Transversus Abdominis Plane Block With Bupivacaine or Ropivacaine Versus Intrathecal Morphine on Opioid-related Side Effects After Cesarean Delivery: A Meta-analysis of Randomized Controlled Trials.

OBJECTIVES

Intrathecal morphine (ITM) is frequently associated with side effects such as postoperative nausea and vomiting (PONV) and pruritus. The aim of this meta-analysis was to compare the impact of transversus abdominis plane (TAP) block versus ITM on side effects following cesarean delivery.

MATERIALS AND METHODS

PubMed, Embase, Web of Science, and CENTRAL were searched for randomized controlled trials that compared TAP with ITM for cesarean delivery. The primary outcomes were opioid-related side effects. The secondary outcomes included pain scores, opioid consumption, patient satisfaction, and time to the first analgesia request.

RESULTS

Seven studies involving 660 patients were included. TAP blocks were performed with bupivacaine or ropivacaine. There was less PONV with TAP versus ITM (risk ratio [RR]=0.45, 95% confidence interval [CI]: 0.33-0.63, P<0.001; I2=0%), but no significant difference in pruritus (RR=0.76, 95% CI: 0.49-1.18, P=0.22; I2=78%) and sedation (RR=0.44, 95% CI: 0.19-1.00, P=0.05; I2=0%). TAP had a greater morphine consumption in 24 hours (mean difference: 5.80 mg; 95% CI: 1.38-10.22 mg, P=0.01; I2=89%) and higher pain score at rest at 6 hours (mean difference: 0.70, 95% CI: 0.39-1.02, P<0.001; I2=56%), but similar pain at rest at 24 hours and on movement compared with ITM. No differences were found in time to first analgesia and patient satisfaction.

DISCUSSION

Compared with ITM, TAP block is associated with less PONV but inferior early analgesia after cesarean delivery. However, the heterogeneity among the studies highlights the need for more well-designed studies to obtain more robust conclusions.