Magnesium sulfate reduces postoperative pain in women with cesarean section: A meta-analysis of randomized controlled trials

Abstract

Objectives: The use of magnesium sulfate (MgSO₄ ) as an adjunct in different anesthetic regimens for cesarean section (CS) delivery often reports conflicting results. This study aimed to review the effectiveness of MgSO₄ on improving postoperative analgesia after CS systematically.

Methods: PubMed, Embase, and the Cochrane library were searched for randomized controlled trials (RCTs) published from inception to February 2020.

Results: A total of 880 women were included (440 in each group). MgSO₄ had a statistically significant effect compared to the control group on the highest VAS (weighted mean difference [WMD] = -0.74, 95% confidence interval [CI] = -1.03 to -0.46, p < 0.001, I² = 91.7%, p_{heterogeneity} < 0.001) and the last VAS (WMD = -0.47, 95% CI = -0.71 to -0.23, p < 0.001, I² = 95.0%, p_{heterogeneity} < 0.001). MgSO₄ prolonged the time to the first use of analgesia compared to the control group (standardized mean difference [SMD] = -3.03 min, 95% CI = -4.32 to -1.74, p < 0.001, I² = 96.3%, p_{heterogeneity} < 0.001). MgSO₄ decreased the consumption of analgesia compared to the control group (SMD = -3.20 mg of IV morphine equivalent, 95% CI: -5.45 to -0.95, p = 0.005, I² = 97.6%, p_{heterogeneity} < 0.001).

Discussion: MgSO₄ decreases the highest VAS in women who underwent general anesthesia, spinal anesthesia, or epidural for CS (all p < 0.05). Additional MgSO₄ significantly reduces postoperative pain in women undergoing CS.

Keywords: cesarean section (CS); magnesium sulfate; meta-analysis; pain; postoperative.