Neuraxial magnesium sulfate improves postoperative analgesia in Cesarean section delivery women: A meta-analysis of randomized controlled trials.

Background: We conducted this meta-analysis to elucidate whether additional neuraxial magnesium sulfate (MgSO) can improve postoperative analgesia in women undergoing Cesarean section (CS) delivery.

Method: We searched Pubmed, Embase and ClinicalTrial.gov. We included only randomized controlled trials that have compared the quality of postoperative analgesia with and without additional neuraxial MgSO in women undergoing CS delivery with neuraxial anesthesia regimens. The primary outcomes included analgesic duration of neuraxial anesthesia, postoperative pain scores and postoperative consumption of analgesics. The secondary outcomes included patients' satisfaction and adverse effects related to postoperative analgesia.

Results: Nine relevant studies comprising a total of 827 women undergoing CS delivery were included. Analyses revealed that CS women receiving additional neuraxial MgSO (the MgSO group) had longer duration of neuraxial anesthesia (effect size [ES] = 1.920, 95% confidence interval [CI] = 0.999 to 2.842, P < 0.001), longer duration of sensory block (ES = 1.020, 95% CI = 0.463 to 1.577, P < 0.001), lower postoperative pain scores at rest (ES = -1.206, 95% CI = -2.084 to -0.329, P = 0.007), pain scores with motion (ES = -1.435, 95% CI = -2.631 to -0.240, P = 0.019) and consumption of analgesics (ES = -1.620, 95% CI = -2.434 to -0.806, P < 0.001) than CS women without receiving additional neuraxial MgSO (the control group). Of note, the MgSO group tended to have higher rate on rating satisfaction as "excellent" than the control group did (odds ratio = 3.748, 95% CI = 2.218 to 6.332, P < 0.001). However, the incidences of adverse effects (i.e., nausea and vomiting, pruritus and hypotension) were not significantly different between these two groups.

Conclusion: Neuraxial MgSO improves postoperative analgesia in CS women.