High-quality colonoscopy is considered the gold standard for the detection and prevention of colorectal cancer, and its efficacy is predicated on optimal colon cleansing.However, about 18%-35% of patients were still reported to suffer inadequate bowel preparation. Although several predictive models exist, the current guideline indicates that there is insufficient evidence to recommend the use of a predictive model for clinical practice.

Inclusion Criteria:

• patients undergoing colonoscopy.
• patients older than 18 years.

Exclusion Criteria:

• Emergency colonoscopy.
• Have a serious medical condition, such as heart failure, acute liver failure, severe kidney disease (dialysis or predialysis patients) or New York heart association class iii-iv.
• Pregnant or breastfeeding.
• No bowel preparation or poor compliance (no bowel preparation as instructed or laxatives < 90% of prescribed dose).
• Refuse to sign informed consent.
• The patient was rescheduled after the previous colonoscopy due to insufficient bowel preparation.
• Temporarily change to colonoscopy for other reasons.
• Incomplete colonoscopy due to insufficient parenteral preparation.
• Lack of complete data.

1. patients undergoing colonoscopy.
2. patients older than 18 years