The colonoscope passes through different parts of the large intestine through the anus to reach the end of the cecum, and then slowly retracts to the end of the small intestine, ascending colon, transverse colon, descending colon, sigmoid colon, rectum back to the anus, doctors can display every part of the large intestine on the high-definition display Observe carefully to find out the hidden scrotum. If necessary, the doctor can use special tools to extract the diseased tissue through the endoscope for testing. The process only takes 20-30 minutes.

Colorectal cancer is the most common cancer in Hong Kong. According to data from the Department of Health, colorectal cancer is the second most common cancer in Hong Kong. In 2016, there were 2,089 colorectal cancer deaths, accounting for 15% of all local cancer deaths. About 85% of bowel cancers originate from intestinal polyps. The process of colorectal cancer evolving from polyps to cancer is about ten years. As long as the polyps in the intestines are detected and removed during this period, it is the most effective way to prevent colorectal cancer.

If it can be detected early, treatment and medical costs are relatively simple and low. High-risk factors for colorectal cancer include age, family history of colorectal cancer, ulcerative colitis, or Crohn's disease. Lack of physical activity, high-fat diet and insufficient fiber, drinking and smoking, and obesity all increase the chance of colorectal cancer; some symptoms include changes in bowel habits (constipation or diarrhea), blood in the stool, and unexplained weight loss and abdominal discomfort.