This study will include adult patients undergoing painless colonoscopy at our hospital. The time required for endoscope insertion to reach the cecum (Cecal Intubation Time, CIT) by physicians of different experience levels will be recorded. CIT roughly reflects the difficulty of colonoscope insertion, which holds important clinical significance and is associated with factors such as abdominal pain, bloating, and the degree of intestinal adhesion. However, due to confounding factors such as operator experience and equipment variability, the objectivity of CIT as an indicator of insertion difficulty is reduced.

In this study, all patients' CIT data will be standardized using three different methods: Z-score standardization, median standardization, and quantile normalization. The goal is to determine which standardized form of CIT can more objectively reflect insertion difficulty and its correlation with important clinical indicators.

The purpose of this study is to establish a novel indicator that can objectively assess colonoscope insertion difficulty across different operating environments, thereby providing a scientific basis for the development of clinical treatment strategies.

Inclusion Criteria:

• Patients who voluntarily undergo colonoscopy

Exclusion Criteria:

• patients who failed to complete the colonoscopy

Patients who undergo colonoscopy at the Second Hospital of Jilin University

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