Effectiveness of ultrasound-guided transversus abdominis plane block vs. intrathecal morphine combined with bupivacaine for postoperative pain management in caesarean section: a prospective cohort study

Abstract

ABSTRACT Background: Postoperative pain following caesarean section is often severe, affecting up to 93% of parturients. It influences maternal outcomes which has an impact on clinical challenge. Ultrasound-guided transverse abdominis plane block and Intrathecal morphine are widely used. However, there is ongoing debate regarding their relative effectiveness, and limited comparative evidence exists in resource-limited setting. This study provides evidence to guide practice, policy, and improve maternal recovery in resource‑limited settings. Objective: To compare effectiveness of Ultrasound-guided transverse abdominis plane block and Intrathecal morphine for postoperative analgesia in parturients undergoing caesarean section. Methods: A prospective cohort study was conducted at Asella Referral and Teaching Hospital from June 1 to September 30, 2025. Systematic random sampling was employed to select parturients undergoing cesarean section. Pain score using numerical rating score, time to first analgesia request, total analgesic consumption, and postoperative outcomes were assessed. Chi-squares, independent t-test, Mann-Whitney test, logistic regression, Linear mixed model, and survival analysis by SPSS v.25, with significance set at p<0.05. Results: 98 participants (49 per group) were included in the study. Both groups had comparable baseline characteristics (p>0.05). Postoperative pain intensity was significantly lower in parturients who received intrathecal morphine (mean difference: 0.86, p<0.001), peaked at 12 hours. It also provides superior analgesic adequacy during movement (OR: 3.65, 95% CI: 2.56-5.24, p<0.001) and a longer time to first analgesia request (median: 7 vs. 5 hours, p <0.001). Analgesic consumption and postoperative outcomes, including side effects and functional recovery, were comparable. Conclusion: Intrathecal morphine provides a lower pain score and a prolonged first analgesia request than Ultrasound-guided transverse abdominis plane block. However, both of them had relatively comparable postoperative analgesia consumption, side effects and safety profiles. Future multicenter randomized control studies are recommended to guide national practice. Key words: Intrathecal morphine, transverse abdominis plane block, cesarean section, postoperative analgesia