The aims of the present study is to compare oral sulfate solution (OSS) with low-dose polyethylene glycol plus ascorbic acid (2-L PEG/Asc) for bowel cleansing efficacy.

High-quality bowel cleansing is critical to effective colonoscopy. Studies in the past decade have demonstrated that many clinical practices continue to have rates of adequate preparation as low as 60% to 80%.

Low-volume preparations for colonoscopy are designed to improve patient tolerability, another important aspect of bowel preparation. In addition, low-volume preparations should ideally not sacrifice efficacy. There are few data comparing the efficacy of available low-volume bowel preparations.

In this study, we describe a prospective, single-blind, randomized, controlled trial comparing oral sulfate solution (OSS) (SUPREP, Braintree Laboratories, Braintree, Mass) with low-dose polyethylene glycol plus ascorbic acid (2-L PEG/Asc).

Inclusion Criteria:

• people who receive colonoscopy
• aged : 18-80
• people who sign the consent

Exclusion Criteria:

• those aged over 80 years
• the disabled
• intestinal obstruction
• severe constipation
• previous history of bowel resection
• liver cirrhosis
• heart failure or ischemic heart disease within 6 months
• inflammatory bowel disease
• pregnant women
• severe renal insufficiency
• people who refuse to sign the consent