Efficacy of magnesium sulphate as an adjuvant for spinal anaesthesia in caesarean sections: A systematic review & meta-analysis

Abstract

Objective: To assess the effectiveness and safety of magnesium sulphate as an adjuvant to hyperbaric bupivacaine in spinal anaesthesia for patients undergoing caesarean section, with special focus on the duration of action, postoperative analgesia, maternal and neonatal outcomes.

Method: The systematic review and meta-analysis was conducted from June to August 2025, and comprised literature search on PubMed, Cochrane Library and Google Scholar databases along with manual search for randomised controlled trials comparing the use of magnesium sulphate as an adjuvant to intrathecal hyperbaric bupivacaine, regardless of dose, with intrathecal hyperbaric bupivacaine with or without placebo in cases of caesarean section. Standardized forms were used to extract data from the trials. Risk of bias assessment was done using the Cochrane RoB tool 2.0.

Results: Of the 12 studies short-listed, 4(33.3%) were subjected to meta-analysis. Intrathecal magnesium sulphate significantly prolonged both sensory and motor blockade (pooled mean difference of 2.75 minutes; 95% CI: 0.44-5.06; p=0.0001 and 1.14 minutes; 95% CI: 0.6-1.92; p=0.0001 respectively, compared with controls. Nausea and vomiting among pregnant women did not show a significant difference between the two groups (odds ratio [OR] = 0.79; 95% confidence interval [CI]: 0.30 to 2.10; p = 0.072). No adverse clinical effects. Inconsistencies across the studies were reported as followed: sensory blockage I²=97.7%, duration of motor block I²=91.6%, time to rescue analgesia I²=97.4%, vomiting or nausea I²=50.5%, postoperative shivering I²=73.8%, and APGAR scores I²=61.4%. All the parameters showed substantial heterogeneity patterns with statistically significant P<0.05.

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