If colonic polyps cause intussusception, a sausage-like mass can be found in the abdomen without pressure pain. Some patients may show signs of intestinal obstruction. Patients with polyps syndrome have complex extra-intestinal signs. Rectal finger diagnosis: rectal finger diagnosis is very important, and it can find rectal and part of sigmoid colon adenoma. If the tumor is smooth, movable, round, soft and elastic, it is mostly suggested to be tubular adenoma. If the tumor is not smooth, lobulated, flat or broad-based and soft, it is often suggested to be villous adenoma. If the tumor is uneven in texture, fixed, with local nodularity and ulcers on the surface, it suggests the possibility of malignant transformation. Fecal occult blood test (FOB): Those who have family history of colorectal tumor or change in stool habit should do fecal occult blood test for primary screening, and if positive, in-depth X-ray air-barium double contrast imaging and endoscopic pick-up should be performed to exclude colorectal adenoma and other gastrointestinal lesions. Third, radiological examination: oral barium examination is observed after the contrast agent reaches the colon 3~6h after taking barium. This examination method has limitations. For colorectal adenomas less than 1 cm in diameter, the leakage rate of ordinary barium enema examination can reach more than 80%, while for those with a diameter of more than 1 cm, the leakage rate is 20% to 50%. Even with the use of gas-barium double contrast imaging, the leakage rate for adenomas >1 cm in diameter is also 10%-30%, and only about 70% of larger lesions can be shown. The most easily missed sites are the sigmoid colon and cecum. The detection rate is also influenced by the experience and technical level of the examiner. However, barium enema can be used as a supplement to colonoscopy for those who cannot complete the entire colorectal examination, and sometimes even detect lesions that cannot be detected by colonoscopy. In patients who are older, in poor general condition and cannot tolerate colonoscopy, the value of X-ray air-barium dual imaging cannot be ignored. The combined application of barium enema and colonoscopy can improve the detection rate of colorectal adenoma. Endoscopy: In the past, the commonly used hard sigmoidoscopy equipment is simple, inexpensive and easy to grasp, but because it is not easy to inflate, and the actual observed intestinal cavity distance is shorter than the length of the tube, so it is gradually eliminated. Fiberoptic colonoscopy can examine the entire colorectum, which is widely used because it helps to diagnose the site and histology of colorectal adenomas and treat them to some extent. Although this pick-up method also occasionally has complications such as bleeding or perforation, it is still safe if the technique is skilled. At present, the success rate of full colorectal imaging is over 90% with the use of electronic colonoscopy. The direct vision and biting histological examination of intestinal mucosal bulging lesions can enable the detection of tumors below 1 cm that are easily missed by barium enema examination. The biopsy of colorectal adenoma should emphasize several points: ① The biopsy site should be typical: the composition of tumor villous-like structure is not consistent in different areas, so multi-point sampling should be emphasized, and for large adenomas, it is generally required to include the center of the tumor and 5 points at 3, 6, 9 and 12. For adenomas with hard nodes, ulcers and other areas with cancerous tendency should be focused on sampling, and preferably excisional biopsy. For rectal adenomas over 2 cm in diameter, especially those without a tip, transanal or transsacral tumor resection is recommended to avoid the leakage of local malignant changes. The leakage rate of adenoma carcinoma can be more than 30% for clamp biopsy or partial excisional biopsy. All tissues excised by endoscopy as a treatment measure should be sent for pathological examination. For large adenomas with malignant potential, intraoperative rapid frozen pathological examination should be performed when the histology of biopsy contradicts with clinical diagnosis. In addition to multi-point sampling, multi-sectioning and preferably continuous sectioning, histological examination should also be performed from a therapeutic perspective to provide comprehensive information for clinical diagnosis and treatment. A qualified pathology report should include: (1) the type of adenoma and the proportion of the villous component. (2) The degree of atypical hyperplasia. ③If there is cancer, the degree of differentiation, depth of infiltration, location and distance from the cut edge of the cancer should be indicated.