“Tests and procedures used for colon/rectal cancer diagnosis include:

• Using a scope to examine the inside of the colon. Colonoscopy uses a long, flexible and slender tube attached to a video camera and monitor to view the whole colon and rectum. A doctor may pass surgical tools through the tube to take tissue samples and remove polyps.
• Removing a sample of tissue for testing. A biopsy is a procedure to remove a sample of tissue for testing in a lab. For colon cancer, the tissue sample is often collected during a colonoscopy. Sometimes surgery is needed to get the tissue sample. In the lab, tests can show whether the cells are cancerous and how quickly they’re growing. Other tests can give more information about the cancer cells. Your health care team uses the results to understand your prognosis and create a treatment plan.
• Blood tests. Blood tests aren’t used to diagnose colon cancer. But blood tests can give clues about overall health, such as how well the kidneys and liver are working. A blood test might be used to look for a low level of red blood cells. This result might indicate that a colon cancer is causing bleeding.