Background Elective cesarean section (ECS) can cause moderate to severe pain that often requires opioid administration. To enhance maternal recovery, and promote mother and baby interaction, it is important to reduce postoperative pain and opioid consumption. Various regional anesthesia techniques have been implemented to improve postoperative pain management following ECS. This study aimed to investigate the efficacy of bilateral ultrasound-guided transmuscular quadratus lumborum (TQL) block on reducing postoperative opioid consumption following ECS.

Methods A randomized double-blind trial with concealed allocation was conducted in 72 parturients who received bilateral TQL block with either 30 mL ropivacaine 0.375% or saline. TQL block injectate was deposited in the interfascial plane between the quadratus lumborum and psoas major muscles, posterior to the transversalis fascia. Primary outcome was opioid consumption, which was recorded electronically. Pain scores and time to first opioid request were also evaluated.

Results Opioid consumption (oral morphine equivalents, OME) was significantly reduced in group ropivacaine (GRO) in the first 24 hours compared with group saline (65 mg OME vs 94 mg OME) with a mean difference of 29 mg OME; 95% CI 3 to 55, p<0.03. Time to first opioid request was significantly prolonged in GRO, p<0.003. Numerical rating scale pain scores were significantly lower in GRO in the first 6 hours after surgery, p<0.03.

Conclusions Bilateral TQL block significantly reduced 24 hours’ opioid consumption. Further, we observed significant prolongation in time to first opioid, and significant reduction of pain during the first 6 postoperative hours.