Endoscopic retrograde cholangiopancreatography (ERCP) is essential for visualising the biliary tree and pancreatic ducts, and carbon dioxide (CO₂) insufflation during ERCP is considered an alternative technique to air insufflation for relieving post-procedural abdominal discomfort (abdominal pain and distension). The aim of the present study was to evaluate the effect of CO₂ insufflation on the remission of abdominal discomfort and the potential side effects by conducting a meta-analysis.

The method recommended by the Cochrane Collaboration was employed to conduct a meta-analysis of randomised controlled trials (RCTs) of CO₂ insufflation versus air insufflation during ERCP. The PubMed, EMBASE, Cochrane Library, ISI Web of Science and China Biology Medicine disc (CBMdisc) databases were comprehensively searched.

Nine high-quality RCTs were reviewed. The updated meta-analysis showed that the CO₂ groups achieved a lower abdominal pain score [1-hour (SMD: −1.44, 95% CI: −2.76, −0.15), 3-hour (SMD: −1.17, 95% CI: −2.18, −0.16) and 6-hour (SMD: −1.39, 95% CI: −2.68, −0.10)], a lower abdominal distension score [1-hour (SMD: −1.05, 95% CI: −1.73, −0.38), 3-hour (SMD: −0.63, 95% CI: −1.10, −0.16) and 6-hour (SMD: −0.54, 95% CI: −0.99, −0.08)] and a lower overall rate of complications (OR: 0.59; 95% CI: 0.37, 0.93). There was no significant difference between the groups regarding abdominal discomfort immediately after recovery or 24-hour post-procedure. There was no evidence to indicate higher pressure of CO₂ (pCO₂) values in the CO₂ groups during the procedure when the patients were under sedation anaesthesia.

Compared to air insufflation, CO₂ insufflation is currently the preferred method for ERCP and decreases post-procedural abdominal pain and distension without significant side effects.