Posteromedial quadratus lumborum block versus wound infiltration after caesarean section: A randomised, double-blind, controlled study.

Background: Reducing pain and minimising the use of opioids after caesarean section are crucial to enhancing maternal recovery and promoting mother-newborn interaction. Various techniques have been implemented to improve analgesia. We compared the analgesic efficacy of posteromedial quadratus lumborum block with that of wound infiltration following elective caesarean section.

Objective: We hypothesised that within a multimodal analgesia approach, posteromedial quadratus lumborum block would, due to its potential to relieve visceral pain, result in a 15% reduction in 24-h postoperative opioid consumption compared with wound infiltration.

Design: A double-blind, randomised, placebo-controlled clinical study.

Setting: A single-centre study between August 2019 and May 2020.

Patients: One hundred and sixteen women were randomly allocated into two groups. In the quadratus lumborum group, 20 ml 0.9% saline was injected into the surgical wound followed by bilateral posteromedial quadratus lumborum block using 20 ml 0.25% levobupivacaine per side. In the wound infiltration group, 20 ml of 0.25% levobupivacaine was injected into the surgical wound followed by a bilateral posteromedial quadratus lumborum injection with 20 ml 0.9% saline per side.

Main Outcome Measures: The primary outcome was opioid (piritramide) consumption at 24 h. Secondary outcomes were piritramide consumption at 48 h, time-to-first analgesic request, pain scores at rest and with movement, surgery-to-first-ambulation time, surgery-to-breastfeeding time, sedation, pruritus and complications.

Results: Piritramide consumption in 24 h was significantly lower with posteromedial quadratus lumborum block (1.5 ± 1.8 mg) than with wound infiltration (2.2 ± 1.7 mg) (P = 0.04), mean difference of -0.7 mg, (95% CI -1.3 to -0.03). In those who required piritramide, time-to-first analgesic request was significantly longer with posteromedial quadratus lumborum block 11 [7 to 14] h, than with wound infiltration 7 [5 to 11] h (P = 0.02). Pain scores were low, with no differences recorded at rest and with movement. There were no differences in time-to-ambulation and time-to-breastfeed between the groups.

Conclusion: As a component of multimodal post-caesarean section analgesia, posteromedial quadratus lumborum block was associated with lower 24-h opioid consumption compared with wound infiltration.

Trial Registration: ClinicalTrials.gov identifier: NCT04000308.