Low volume bowel preparation for colonoscopy: randomized, endoscopist-blinded trial of liquid sodium phosphate versus tablet sodium phosphate

Am J Gastroenterol. 2003 Apr;98(4):827-32. doi: 10.1111/j.1572-0241.2003.07380.x.


Objective: The aim of this study was to compare the colon-cleansing effectiveness, ease of consumption, and side effect profiles of two commercially available preparations of sodium phosphate: liquid Fleet Phospho-soda and Visicol tablets.

Methods: Outpatients undergoing elective colonoscopy were sequentially randomized to one of two preparation groups: liquid: 45 ml at 7:00 PM, 45 ml 3 h before colonoscopy; or tablet: 20 tablets at 7:00 PM, 20 tablets 3-5 h before colonoscopy. Subjects rated preparation tolerability on a 5-point Likert scale. A Residual Stool Score was calculated for each subject based on the amount of stool, consistency of residual stool, and percent of bowel visualized (range 0-11, 0 = best). The endoscopists were blinded to the preparation used.

Results: A total of 101 subjects were enrolled (43 male, 58 female, mean age 58.2 yr). The groups were similar in age and indications for colonoscopy. Overall, bowel cleansing was rated "Excellent" or "Good" in 92% of liquid preparation subjects, compared with 74% of tablet preparation subjects (p = 0.03). Subjects in the liquid group demonstrated significantly less residual stool than did tablet subjects (Residual Stool Scores: liquid 1.3 +/- 1.2 vs tablet 1.9 +/- 1.5, p < 0.05). Subjects rated the liquid preparation easier to swallow (p < 0.005) and more convenient to take (p < 0.005) than tablets. Among liquid subjects, 45 of 50 reported a willingness to take their preparation for future colonoscopies, compared with 36 of 49 who took tablet sodium phosphate (p < 0.04).

Conclusions: Liquid sodium phosphate is better tolerated and more effective at colon cleansing when compared with sodium phosphate in tablet form.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Adult
  • Aged
  • Attitude of Health Personnel
  • Cathartics / administration & dosage*
  • Cathartics / therapeutic use*
  • Colonoscopy*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Patient Satisfaction
  • Pharmaceutical Solutions*
  • Phosphates / administration & dosage*
  • Phosphates / therapeutic use*
  • Preoperative Care
  • Single-Blind Method
  • Tablets*


  • Cathartics
  • Pharmaceutical Solutions
  • Phosphates
  • Tablets
  • sodium phosphate