Quadratus Lumborum Block vs Intrathecal Morphine for Post-Cesarean Analgesia

In the Quadratus Lumborum block group, Participants will be placed in the lateral decubitus position. A convex ultrasound probe will be placed in sterile conditions along the midaxillary line, in the subcostal area above the iliac crest, to visualize the quadratus lumborum and psoas major muscles, as well as the L4 vertebral transverse process. Using an in-plane technique, a 22G, 100 mm peripheral block needle will be advanced anterior to the quadratus lumborum muscle and into the subfascial space between the quadratus lumborum and psoas major muscles. After confirming the correct location with hydrodissection, 20 mL of 0.25% bupivacaine will be injected slowly, observing the fascial displacement on ultrasound. The same procedure will be repeated on the contralateral side.

In the intrathecal morphine group, 100 micrograms of morphine (0.1 mL) will be added to the 12 mg of intrathecally administered bupivacaine.