The analgesic efficacy of ultrasound-guided transversus abdominis plane block in comparison with subarachnoid morphine after cesarean section in morbidly obese parturients

Abstract

Context Cesarean section is one of the most commonly performed surgical procedures. Intrathecal morphine is a popular and effective option for pain management following cesarean section. It is associated with side effects such as nausea, vomiting, pruritus, urinary retention, reactivation of oral herpes, and, rare but life-threatening, respiratory depression. The interest in transversus abdominis plane (TAP) block as a post-cesarean-delivery analgesic modality has surged in the past few years, and many studies have evaluated and compared its efficacy with intrathecal morphine. Aim The aim of the study was to compare spinal morphine and bilateral TAP block in cesarean section in morbidly obese parturients with respect to their postoperative analgesic efficacy and narcotic consumption. Settings and design This was a prospective randomized, double-blinded study. Materials and methods Parturients, 20 years or older, with BMI greater than 35 kg/m 2 , who were scheduled to undergo elective cesarean section were recruited for the study. They were assigned to receive either intrathecal morphine (the ITM group) 0.1 mg or TAP block (the TAP group) using ropivacaine 0.5% 20 ml on each side. The primary outcome was pain on movement, from supine to sitting position. The secondary outcomes were the presence and severity of nausea and pruritus and the presence of respiratory depression. Results We enrolled 60 patients, of whom 59 were analyzed. The numeric rating scale score for pain was less in the ITM group than in the TAP block group, and this difference was statistically significant. Both pruritus and nausea happened in more patients in the ITM group than in the TAP block group, and this difference was statistically significant in both the 8 and 16 h observations. Conclusion In morbidly obese parturients, intrathecal morphine has superior post-cesarean-delivery analgesic efficacy compared with the TAP block.