TAP block with intrathecal fentanyl or intrathecal morphine for cesarean analgesia

Post-cesarean delivery pain management traditionally relies on intrathecal morphine for its potent, long-lasting effects. However, adverse effects such as pruritus and the limited availability of preservative-free morphine in some settings necessitate alternative strategies. This randomized clinical trial compared the effectiveness of combining a transversus abdominis plane (TAP) block with intrathecal fentanyl against intrathecal morphine for post-cesarean analgesia within a multimodal regimen.

Study objective and methods

The randomized, double-blind, non-inferiority trial aimed to determine if TAP block combined with intrathecal fentanyl could provide non-inferior analgesia compared to intrathecal morphine.

• Participants: 80 women undergoing cesarean delivery under spinal anesthesia, randomized into two groups:
  • TF group: Intrathecal fentanyl (10 µg) and lateral TAP block with 15 mL of 0.375% ropivacaine per side.
  • M group: Intrathecal morphine (75 µg) and a saline sham block.
• Primary outcome: Pain scores during movement at 24 hours post-surgery, using the numeric rating scale (NRS).
• Secondary outcomes: Opioid consumption, time to first opioid request, pruritus, nausea, patient satisfaction, and neonatal outcomes.

Key findings

• • Pain scores: At 24 hours, pain scores during movement were 5.4 in the TF group and 4.8 in the M group (mean difference (95% CI): 0.6 (−0.3 to 1.5), p = 0.202). The upper CI exceeded the non-inferiority margin, indicating that non-inferiority was not demonstrated.
  • Opioid use: Postoperative fentanyl consumption was higher in the TF group (median: 585 µg vs. 140 µg; p < 0.001).
  • Side effects: Pruritus was significantly more frequent in the M group (60% vs. 10%; p < 0.001).
• Other outcomes: Time to first opioid request was shorter in the TF group (median: 11.6 hours vs. 16.8 hours; p < 0.001). Patient satisfaction and neonatal outcomes were comparable between groups.

Conclusion

The TAP block combined with intrathecal fentanyl did not achieve non-inferior pain control compared to intrathecal morphine. However, its favorable side-effect profile, particularly the significantly lower incidence of pruritus, suggests it is a reasonable alternative when minimizing opioid-related side effects is a priority.

Future research

Future studies should investigate optimal analgesic combinations and dosing strategies to balance efficacy and side effects. Exploring alternatives to intrathecal morphine in resource-limited settings will also improve maternal care outcomes.

For more detailed information, refer to the full article in RAPM.

Park S, Kim Y, Kim H, et al. Transversus abdominis plane block combined with intrathecal fentanyl versus intrathecal morphine for post-cesarean analgesia: a randomized non-inferiority clinical trial. Reg Anesth Pain Med. Published online January 21, 2025.

Download the Nerve Blocks App HERE for in-depth insights on the TAP block. Prefer a physical copy? The bestselling NYSORA Nerve Blocks App is available in book format — an essential resource for mastering nerve blocks! And for a digital learning experience, check out the Nerve Blocks Manual Course on NYSORA’s LMS!