Normal saline vs. lactated ringer’s for fluid resuscitation in acute pancreatitis: a systematic review and meta-analysis

Background Intravenous fluid resuscitation is fundamental in acute pancreatitis (AP), but optimal crystalloid selection remains debated. This meta-analysis compares lactated ringer’s (LR) and normal saline (NS) for outcomes in AP. Methods We conducted the systematic review and meta-analysis in accordance with the PRISMA 2020 guidelines. We systematically searched PubMed, Web of Science, Embase, CNKI, and WanFang (Until July 2025) for studies comparing LR and NS in AP. Primary outcomes included mortality, systemic inflammatory response syndrome (SIRS), ICU transfer, pancreatic necrosis, organ failure, and hospital length of stay (LOS). Random- or fixed-effects models were used based on heterogeneity ( I 2 ). Results Overall mortality did not differ between LR and NS (OR = 1.020, 95% CI: 0.865–1.359, p = 0.895). No mortality benefit was observed for LR in any severity subgroup, including severe acute pancreatitis (SAP) (OR = 0.931, 95% CI: 0.157–5.505, p = 0.937). LR significantly shortened LOS in RCTs (SMD = −0.307, 95% CI: −0.511 to −0.102, p = 0.003) and small-sample studies (100 cases; SMD = −0.271, 95% CI: −0.519 to −0.022, p = 0.033), but the overall pooled analysis showed no significant difference (SMD = −0.121, p = 0.201). Notably, SAP patients receiving LR had a longer LOS (SMD = 0.368, 95% CI: 0.072–0.664, p = 0.015). No significant differences were observed for SIRS, ICU transfer, pancreatic necrosis, or organ failure, though organ failure showed a non-significant trend favoring LR (OR = 0.563, p = 0.063). High heterogeneity existed in non-RCT and large-sample (100 cases) subgroups. Trial sequential analysis confirmed true negative findings for mortality, ICU transfer and SIRS, but indicated insufficient power for pancreatic necrosis, organ failure and LOS. Conclusion LR and NS demonstrate comparable mortality and safety profiles, with no significant difference in overall LOS. Although LR may shorten LOS in certain subgroups, its association with prolonged LOS in patients with SAP requires further validation. Therefore, based on current evidence, no preference can be recommended for either fluid, and larger standardized trials are warranted. Systematic review registration CRD420251112118.