Effects of preemptive analgesia on acute postoperative pain, 24-hour PCEA consumption, haemodynamic parameters, and adverse events following caesarean section: a systematic review and meta-analysis.

BACKGROUND: Preemptive analgesia, defined as the initiation of multi-target and multi-mechanism analgesic interventions prior to noxious stimulation, has been suggested to reduce postoperative pain intensity, decrease opioid consumption, and minimise pain-related adverse events following caesarean section. METHODS: A systematic search was conducted in PubMed, Cochrane Library, Web of Science, MEDLINE, ClinicalTrials.gov, CNKI, VIP, and Wanfang databases up to December 31, 2025. Meta-analysis was conducted using STATA to evaluate the effects of preemptive analgesia on postoperative acute pain, physiological parameters, and adverse events in women undergoing caesarean section. RESULTS: A total of 17 RCTs involving 1,277 participants were included. Meta-analysis demonstrated that preemptive analgesia significantly reduced postoperative acute pain following caesarean section, but did not significantly decrease 24-hour patient-controlled epidural analgesia (PCEA) consumption. In addition, no significant reduction in mean arterial pressure was observed, whereas slight decreases in oxygen saturation and heart rate were noted. No significant effect on postoperative adverse events was identified. For postoperative pain, subgroup analyses indicated that study location - which was fully confounded with study quality - was a significant source of heterogeneity, with a larger pooled effect in trials from East Asia (SMD -2.59, 95% CI -3.20 to -1.98) than in those from West Asia or the Middle East (SMD -1.07, 95% CI -1.82 to -0.32; P for subgroup differences = 0.048). For 24-hour PCEA consumption, none of the prespecified subgroup factors (maternal age, type of analgesic agent, route of administration, study location, or study quality) explained the observed heterogeneity. CONCLUSIONS: Preemptive analgesia demonstrates clear efficacy in reducing postoperative acute pain following caesarean section, indicating promising clinical applicability. However, its effects on 24-hour analgesic consumption and overall adverse events remain limited. Further large-scale, high-quality randomised controlled trials are warranted to validate the effectiveness of different preemptive analgesia strategies in this population.