Can erector spinae plane block replace intrathecal morphine in cesarean section? A prospective randomized controlled study on opioid consumption.

Objectives: After cesarean, optimal analgesia is important for early mobilization, mitigating thromboembolic risks, and mother-infant communication. Our study aims to compare the postoperative analgesic effects of intrathecal morphine (ITM) and Erector Spinae Plane Block (ESPB) in elective cesarean section under spinal anesthesia.

Methods: 82 patients were randomized into ESPB and ITM groups. Both groups received spinal anesthesia with 10 mg of heavy bupivacaine. In the ITM group, intrathecal morphine (100 mcg) was added. The ESPB group received bilateral T10 level ESPB with 20 ml 0.25% bupivacaine postoperatively. Postoperative pain control included intravenous paracetamol 4x1gr, intravenous patient-controlled analgesia with tramadol, and diclofenac 75 mg for rescue analgesia when NRS > 4. NRS, tramadol consumption, and side effects were recorded 24 hours postoperatively. The primary outcome of this study is to compare 24-hour postoperative opioid consumption after cesarean sections. Secondary outcomes include postoperative pain scores, rescue analgesia needs, and potential side effects.

Results: NRS scores ≤ 4 at all time intervals and were comparable among groups. The total 24-hour tramadol consumption was significantly higher in ESPB group (median: 75; Q1,Q3[40,140]) compared to ITM (50 [27.5,60], P = 0.008). Tramadol consumption was similar among groups during 0-6 and 6-12 hours. In the 12-24 hours, it was significantly higher in ESPB group (22.5 [15,57.5]) compared to ITM (15 [12.5,25],P = 0.005). In ITM group, nausea and vomiting were observed in 3 patients, itching in 1 patient; no adverse effects were observed in ESPB group.

Discussion: Patients undergoing cesarean section under spinal anesthesia, intrathecal morphine reduced opioid consumption more effectively than ESPB. ESPB is not recommended as a primary analgesic option for cesarean sections.