Comparison of using the same-day 2 sachets picosulfate versus high volume PEG bowel preparation for afternoon colonoscopy Morning only same-day 2 sachets picosulfate may enhance patient tolerability and have similar bowel cleansing efficacy compared to standard method using high volume split-dose PEG.

The investigators aimed to evaluate the efficacy and tolerability of bowel preparation protocols with same-day 2 sachets picosulfate compared to conventional high volume (4L) split-dose for afternoon colonoscopy.

Split-dose PEG (4L) regimens is a standard regimen for bowel preparation because it has better preparation quality and tolerability than single dose 4L PEG regimens. However, although patients drink each 2L separately, the total volume of 4 L PEG is still quite burdensome volume to ingest. In addition, in split dose method, night dose of day before the procedure make patient to suffer from sleep disturbance because of frequent diarrhea and abdominal discomfort.

The investigators aimed to evaluate the efficacy and tolerability of bowel preparation protocols with same-day 2 sachets picosulfate compared to conventional high volume (4L) split-dose for afternoon colonoscopy.

Inclusion Criteria:

• Adult outpatients who undergo afternoon colonoscopy for screening, surveillance or with symptoms

Exclusion Criteria:

• pregnancy,
• breast feeding,
• prior history of surgical large bowel resection,
• severe medical condition such as severe cardiac,
• hepatic, or
• renal failure (creatinine ≥ 3.0 mg/dL (normal 0.8-1.4 mg/dL)),
• significant gastric paresis or gastric outlet obstruction or ileus,
• known or suspected bowel obstruction or perforation,
• drug addiction or major psychiatric illness,
• allergy to PEG and refusal to participate in the study