Intramuscular quadratus lumborum block improves post-cesarean analgesia compared to anterior approach

This randomized controlled trial evaluated 128 parturients undergoing cesarean delivery, randomizing them to receive either an intramuscular quadratus lumborum block (QLB4) or an anterior quadratus lumborum block (QLB3). The study assessed analgesic efficacy and safety over a 48-hour follow-up period. Secondary outcomes included butorphanol consumption, PCA utilization, pain scores, block duration, adverse events, and maternal satisfaction. The study design supports causal inference for the reported outcomes, although specific effect sizes and absolute numbers were not reported for most metrics.

Regarding efficacy, the QLB4 group demonstrated significantly lower 24/48-hour butorphanol use and fewer PCA presses between 6 and 24 hours compared to the QLB3 group (p < 0.05 for both). Pain scores measured at 6 and 12 hours were also lower in the QLB4 group (p < 0.05). Additionally, the block resolution rate was much lower in the QLB4 group at 12 to 24 hours, indicating a longer duration of action (p < 0.05). However, no significant between-group differences were observed for late-stage opioid use or late-stage pain scores.

Safety analysis revealed a lower incidence of lower extremity hypoesthesia in the QLB4 group (0%) compared to the QLB3 group (46.88%). No significant between-group differences were found for other adverse events. Serious adverse events and discontinuations were not reported. The study did not report tolerability data or specific primary outcomes. Limitations include the absence of reported effect sizes, absolute numbers, and a specified primary outcome, which restricts the precision of the clinical interpretation.