BackgroundCesarean section (CS) is the most frequently performed obstetric procedure globally, and postoperative pain remains a prominent concern. This study aimed to evaluate the effectiveness of the bilateral transversus abdominis plane (TAP) block in addressing this issue.MethodsWe performed a randomized trial in women with term pregnancies who underwent elective CS with spinal anesthesia. The women were randomized (1:1) to receive bilateral TAP or postoperative systemic analgesics (control group). The primary outcome was the effect on postoperative pain assessed using the numeric rating score (NRS) at 2, 6, 12, and 24 h in the postoperative period.ResultsAt 2 and 6 h after the surgical procedure, there was a significant reduction in both resting (rNRSp= 0.004) and movement-related pain (dNRSp= 0.0001,p= 0.001 respectively). However, at 12 h, a reduction of dNRS was demonstrated (p= 0.0001), while no benefit was observed at rest. The percentage of women with NRS ≤ 4 was higher after the block at 2 h for both resting and movement-related pain (rNRSp= 0.010; dNRSp= 0.0001); at 6 and 12 h, it was only significant for dNRS (p= 0.002). Rescue doses of analgesics were significantly higher in the control group at 2, 6, and 12 h (p= 0.01,p= 0.0383,p= 0.0003 respectively). No complications with the procedure were recorded.ConclusionBilateral TAP block has the potential to alleviate postoperative pain and reduce the need for additional analgesics after CS.Trial registrationThis study is registered with ClinicalTrials.gov, number (NCT02801968), registered 28 May 2016,https://clinicaltrials.gov/ct2/show/NCT02801968?term=NCT02801968&draw=2&rank=1