A randomized single-blind trial of whole versus split-dose polyethylene glycol-electrolyte solution for colonoscopy preparation

Gastrointest Endosc. 2003 Jul;58(1):36-40. doi: 10.1067/mge.2003.318.


Background: Colonoscopy preparation regimens are often poorly tolerated because they require use of large-volume bowel preparation solution and diet restrictions for adequate cleansing. This study evaluated the efficacy and tolerability of a split-dose polyethylene glycol-electrolyte solution plus bisacodyl and a regular diet.

Methods: A total of 187 patients (104 men, 83 women; age range 18-91 years) were randomly assigned to receive either 3 L of polyethylene glycol-electrolyte solution (n = 96; Group A) with a liquid diet on the day before colonoscopy, or 2 L of polyethylene glycol-electrolyte solution, one tablet of bisacodyl, and a minimally restricted diet on the day before colonoscopy, and then 1 L of the same solution on the day of colonoscopy (n = 91; Group B). Acceptability, adverse events, and willingness to retake the preparation were assessed by questionnaire. The quality of the preparation was graded by an endoscopist, blinded to the type of preparation, by using a previously described scale (excellent to poor).

Results: There were 96 patients in Group A and 91 in Group B. Colon cleansing was significantly better in Group B with regard to the overall quality of the preparation (p lt; 0.05). Compliance was significantly higher in Group B as evidenced by the lower number of patients who discontinued the preparation (4 vs. 15; p = 0.02) because of side effects such as nausea or vomiting. The degree of discomfort, adverse events, and willingness to retake the preparation were not significantly different between the groups.

Conclusions: Colonic preparation with split-dose polyethylene glycol-electrolyte provided better quality colon cleansing and higher compliance, with less dietary restrictions, than preparation with whole-dose polyethylene glycol-electrolyte.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Chi-Square Distribution
  • Colonoscopy / methods*
  • Detergents / pharmacology*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Patient Compliance
  • Polyethylene Glycols / adverse effects
  • Polyethylene Glycols / pharmacology*
  • Probability
  • Sensitivity and Specificity
  • Single-Blind Method
  • Therapeutic Irrigation / methods*


  • Detergents
  • Polyethylene Glycols