In pregnant females, the ultrasonography-guided bilateral posterior approach of quadratus lumborum block (QLB) improved patient satisfaction and reduced pain score at rest at 6 hours compared to the sham procedure after cesarean section performed with spinal anesthesia without intrathecal morphine, according to the findings of a randomized controlled, double-blind study. Researchers undertook this study to determine QLB's efficacy for analgesia after cesarean section.

The study recruited 100 American Society of Anesthesiologists (ASA-II) women with singleton, full-term pregnancy (≥ 37 weeks of gestation) scheduled to undergo cesarean section using spinal anesthesia. Participants were randomly allocated into the quadratus lumborum group (n=50) and control group (n=50). Following completion of cesarean section, a bilateral sham procedure was carried out in the control group and bilateral posterior QLB (20 mL bupivacaine 0.25% on each side) was carried out in the quadratus lumborum group.

The major endpoint was pain score at rest at six hours following cesarean section. The median (range) of pain score at rest at six hours was considerably reduced in the quadratus lumborum group when compared to the control group, as shown in Table 1:

The pain score at rest at twelve hours and pain scores on movement at six and twelve hours were reduced in the quadratus lumborum group. There were no profound inter-group differences noted in pain scores on movement at 24 hours and pain scores at rest. The quadratus lumborum group exhibited greater patient satisfaction, longer time to the first request of morphine, decreased number of people requesting morphine, and minimized total morphine dose.

Regarding the occurrence of pruritus and nausea/vomiting, no profound inter-group differences were noted. Hence, the bilateral posterior quadratus lumborum block imparts adequate postsurgery analgesia after cesarean section.