This study has three main purposes：screening: the first purpose is to evaluate the diagnostic value of combintion of the life risk factors and immunochemical fecal occult blood test (FIT) on detection of colorectal neoplasia in Chinese population; resection: the second objective is to investigate the complete resection rate of colorectal adenoma and risk factors of incomplete resection in China; identification and classification: the third objective is to initially establish an artificial intelegence-assissted recognition and classification system of polyp based on deep learning.

This study is a multi-center cross-sectional survey and diagnostic test led by the National Clinical Research Center for Digestive Disease (Shanghai) (Department of Gastroenterology, Changhai Hospital, Naval Medical University), which is conducted at about 175 digestive endoscopy centers nationwide in China, with the expectation of including 12,000 patients (10,000 screenig and 2,000 adenoma resection). The basic characteristics of patients, bowel preparation method and quality, and related information of colonoscopy are recorded in detail. According to the research purpose, the whole project can be divided into three sections.

1. Screening section: All patients receive FIT test and colonoscopy, whose age, sex, family history, smoking history, body mass index (BMI), diabetes and other risk factors are collected by researchers through pad, equipped with a specially designed database and app. Using colonoscopy results as the gold standard, the risk prediction model for the Chinese population is explored, and the optimal strategy of colonoscopy practice for the Chinese established initially.
2. Resection section: During the polypectomy, for all pathologically confirmed or NBI-predicted adenomas with size<10mm, 1-2 biopsies were randomly performed on the edge after resection to determine the completion rate of the polypectomy.
3. Identification and classification section: For Patients regardless of cancer diagnosis or polypectomy, if there is polyp, observation of narrow band imaging (NBI) with or without magnification is required, with 4 white light and NBI images collected and reserved, respectively. If there is magnifying endoscopy, another 4 endoscopic images of magnification are also required. Endoscopists are invited to predict the pathology of polyps according to the NBI International Colorectal Endoscopic (NICE) classification principle and endoscopic images, and upload the pathological results and endoscopic images within 2-4 week after colonoscopy.

Inclusion Criteria:

1. Age between 18 to 75 years old and patients with or without alarming gastrointestinal symptoms were analyzed separately.
2. 3-4 L polyethylene glycol and foaming agent are used for bowel preparation.
3. Withdrawal time ≥6mins (excluding the time of biopsy)

Exclusion Criteria:

1. A history of acute myocardial infarction (within 6 months), severe heart, liver, kidney dysfunction, or mental illness.
2. Patients taking anticoagulants such as aspirin and warfarin, or who have coagulopathy.
3. Patients with inflammatory bowel disease and colon polyposis.
4. History of colonic procedure (including surgery, polypectomy, EMR, and ESD) in the screening section
5. Diameter of polyp greater than 1cm, lateral developmental lesions (LST), colon cancer, lesions requiring ESD and surgery
6. Patients participating in other clinical trials now or within 60 days.
7. Intestinal obstruction.

Patients who referred to the outpatient and received colonoscopy.