Transversus abdominis plane block vs. wound infiltration in C aesarean section: a randomised controlled trial

Background Multiple studies suggest that transversus abdominis plane ( TAP ) block (without intrathecal morphine) after C aesarean section ( CS ) reduces post‐operative morphine consumption. In our study, we wanted to compare the analgesic effect of TAP block with infiltration of the wound after CS . Methods We included 60 pregnant women scheduled for elective CS under spinal anaesthesia in a randomised, single‐centre, double‐blind study. Thirty patients received ultrasound‐guided TAP block using 20 ml bupivacaine 0.25% with adrenaline 5 μg/ml bilaterally and 20 ml normal saline as wound infiltration ( TAP group). The other 30 patients (the control group) received normal saline 20 ml bilaterally in the TAP , and 20 ml bupivacaine 0.25% with adrenaline 5 μg/ml as wound infiltration. The main outcome was cumulative morphine consumption at 48 h after surgery. In addition, continuous morphine consumption, pain scores and side effects were registered. Results Fifty‐seven patients completed the study. Cumulative morphine consumption at 48 h (mean ± standard deviation) was 41 ± 34 mg in the TAP group and 38 ± 27 mg in the control group ( P  = 0.7); a difference of 3 mg (95% confidence interval −13 to 19 mg). Morphine consumption at any time up to 48 h was virtually identical in both groups. Side effects were similar, except for a higher degree of sedation in the TAP group ( P  = 0.04). Conclusion Compared with wound infiltration with local anaesthetics, TAP block did not reduce cumulative morphine consumption following CS . The TAP block was associated with more pronounced sedation.