High quality bowel cleaning preparation was most important prerequisites of a accurate colonoscopy, because even a small amount of residual fecal matter can obscure small polyps and increase unnecessary procedure time. Until now, several studies evaluated the impact of bowel preparation on the quality of colonoscopy using comparison of the polyp detection rate in patients with adequate bowel preparation status to that in patients with inadequate bowel preparation status during colonoscopy. However, there was no direct measurement the effect bowel preparation status on the polyp missing rate, the quality of colonoscopy, using tandem colonoscopic evaluation in prospective setting.

1. Study flow

1. All patients perform Colonoscopy

   • record the polyp size, shape, location and number

   • record the factors affecting polyp missing rate

     • Patients' age / gender
     • Indication of colonoscopy
     • colonoscopist career
     • colonoscopy withdrawal time
     • bowel preparation status according to scale of U.S. Multi-Society Task Force on colorectal cancer, Aronchick's scale and Ottawa bowel preparation quality scale

2. the patients needed or wanted to 2nd stage colonoscopic polypectomy (2nd stage polypectomy was performed within 6 month)

   • record additionally detected polyp - size, shape, location and number

Inclusion Criteria:

• The patients underwent colonoscopy and 2nd stage colonoscopic polypectomy at Konkuk University Medical Center

Exclusion Criteria:

• Colonoscopy was not reached the caecum
• The patients with 10 or more polyps (who suspected polyposis syndrome)
• Bowel preparation was inadequate when 2nd stage colonoscopic polypectomy
• The patients with inflammatory bowel disease or suspected inflammatory bowel disease
• The patients had a history of bowel resection

The patients underwent colonoscopy and 2nd stage colonoscopic polypectomy at Konkuk University Medical Center