Impact of Bowel Preparation With Low-Volume (2-Liter) and Intermediate-Volume (3-Liter) Polyethylene Glycol on Colonoscopy Quality: A Prospective Observational Study

Digestion. 2015;92(3):156-64. doi: 10.1159/000439299. Epub 2015 Sep 10.


Background/aims: Two-liter polyethylene glycol (PEG) is the most commonly used bowel-cleansing regimen in Taiwan, but its efficacy is unsatisfactory. The aim of this study was to compare 2-liter and 3-liter PEG in terms of their impact on colonoscopy quality among an average-risk population.

Methods: Two-liter PEG was provided between August 2012 and May 2013, while 3-liter PEG was provided between June 2013 and March 2014. A split-dose regimen was provided for morning colonoscopy and a same-day regimen was provided for afternoon colonoscopy. The level of bowel cleansing was prospectively scored.

Results: A total of 407 consecutive subjects completed the 2-liter regimen, and another 407 consecutive subjects completed the 3-liter regimen. The 3-liter group had a significantly higher rate of excellent or good preparations, equivalent to a Boston bowel preparation scale of ≥7, than the 2-liter group (90 vs. 73%, p < 0.0001). More subjects in the 3-liter preparation group compared with the 2-liter group had overall adenoma (70 vs. 54%, p < 0.0001), proximal adenoma (47 vs. 35%, p = 0.0006), sessile serrated adenoma (28 vs. 6%, p < 0.0001), and advanced adenoma (21 vs. 9%, p < 0.0001).

Conclusions: Three-liter PEG provided better cleansing quality and higher adenoma detection rate than 2-liter PEG.

Publication types

  • Comparative Study
  • Observational Study

MeSH terms

  • Adenoma / diagnosis*
  • Adult
  • Aged
  • Cathartics / administration & dosage*
  • Colonic Neoplasms / diagnosis*
  • Colonoscopy*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Outcome Assessment, Health Care
  • Polyethylene Glycols / administration & dosage*
  • Prospective Studies


  • Cathartics
  • Polyethylene Glycols