A meta-analysis of the safety and efficacy of 2 L versus 3 L polyethylene glycol in bowel preparation for colonoscopy

To systematically evaluate the safety and efficacy of 2 L polyethylene glycol (PEG) versus 3 L PEG in bowel preparation for colonoscopy, and to assess whether 2 L PEG can serve as a safe and effective standard regimen. A comprehensive search was conducted in PubMed, Embase, Cochrane Library, Web of Science, Chinese Biomedical Literature Database (CMB), CNKI, Wanfang, and VIP databases from inception to November 22, 2024. Literature screening, data extraction, and quality assessment were performed according to the Cochrane Handbook 5.1.0. Meta-analysis was conducted using RevMan 5.4 and stata 15.0 software. Thirteen randomized controlled trials involving a total of 8,953 participants were included. The meta-analysis showed no statistically significant differences between the 2 L and 3 L PEG groups in terms of bowel preparation success rate (RR = 0.93, 95% CI:0.84–1.02, P = 0.12), high-quality preparation rate (RR = 0.74, 95% CI:0.53–1.04, P = 0.09), or polyp detection rate (RR = 0.99, 95% CI: 0.95–1.03, P = 0.62). However, the 2 L PEG group had significantly lower incidence of nausea (RR = 0.81, 95% CI: 0.71–0.92, P = 0.002), vomiting (RR = 0.70, 95% CI: 0.56–0.87, P = 0.001), bloating (RR = 0.73, 95% CI: 0.57–0.93, P = 0.01), and abdominal pain (RR = 0.73, 95% CI: 0.56–0.95, P = 0.02). Moreover, the willingness to repeat colonoscopy was significantly higher in the 2 L group compared to the 3 L group (RR = 1.22, 95% CI: 1.16–1.29, P < 0.01). The 2 L PEG regimen can be considered a safe and effective standard option for bowel preparation. It offers comparable cleansing efficacy to 3 L PEG while reducing adverse events and enhancing patient willingness to undergo repeat colonoscopy.