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 compared the postoperative analgesic effects of intrathecal morphine (ITM) and erector spinae plane block (ESPB) in elective cesarean section under spinal anesthesia. Methods: Eighty-two patients were randomized into ESPB and ITM groups. Both groups received spinal anesthesia with 10 mg of heavy bupivacaine. In the ITM group, ITM (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 4x1 g, intravenous patient-controlled analgesia with tramadol, and diclofenac 75 mg for rescue analgesia when Numeric Rating Scale (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 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 the ESPB group (median: 75; Q1, Q3 [40, 140]) compared with ITM (50 [27.5, 60], P = 0.008). Tramadol consumption was similar among groups during 0 to 6 and 6 to 12 hours. In the 12 to 24 hours, tramadol consumption was significantly higher in the ESPB group (22.5 [15, 57.5]) compared with ITM (15 [12.5, 25], P = 0.005). In the ITM group, nausea and vomiting were observed in 3 patients and itching in 1 patient; no adverse effects were observed in the patients in the ESPB group. Conclusion: For patients undergoing cesarean section under spinal anesthesia, ITM reduced opioid consumption more effectively than ESPB. ESPB is not recommended as a primary analgesic option for cesarean sections.