There is no such thing as a simple self-test for bowel cancer. Bowel cancer usually refers to colon cancer and rectal cancer according to the site of occurrence. Early symptoms of both are not obvious. Colon cancer can be diagnosed mainly by colonoscopy and X-ray barium enema. Low rectal cancer can be palpated by rectal palpation. Upper rectal cancer also requires endoscopy, which should be performed by specialized physicians, and self-examination is not recommended. Although self-examination is not recommended, it can be slightly judged by changes in daily performance. Changes in bowel habit and fecal character are the earliest symptoms of colon cancer. They include increased frequency of bowel movements, diarrhea, constipation, blood, pus or mucus in feces. Abdominal pain may also appear, which is mostly persistent hidden pain with inaccurate localization. Sometimes, abdominal mass can be seen. Systemic symptoms manifest as anemia, emaciation, fatigue and so on. Common manifestations of rectal cancer include rectal irritation, frequent bowel movement, change of bowel habit, feeling of falling in anus before defecation, feeling of incomplete defecation, lower abdominal pain in advanced stage, blood on the surface of stool or even pus-blood stool. When cancer invasion leads to narrowing of intestinal lumen, obstruction manifestations such as abdominal pain and distension may appear. Most bowel cancers occur after the age of 50. Therefore, colonoscopy is recommended after the age of 50, and earlier to the age of 40 if there is a family history of bowel cancer, which can observe the whole large intestine from anus to ileum and allow early management of pre-cancerous lesions and regular screening for colorectal cancer. If the above symptoms occur, you should consult a doctor for relevant examinations in time to avoid delaying your condition.