What is a colonoscopy?

Colonoscopy lets your doctor examine the lining of your large intestine (colon) for abnormalities by inserting a thin flexible tube, as thick as your finger, into your anus and slowly advancing it into the rectum and colon. This instrument, called a colonoscope, has its own lens and light source and it allows your doctor to view images on a video monitor.

Why is colonoscopy recommended?

Colonoscopy may be recommended as a screening test for colorectal cancer. Colorectal cancer is the third leading cause of cancer deaths in the United States. Annually, approximately 150,000 new cases of colorectal cancer are diagnosed in the United States and 50,000 people die from the disease. It has been estimated that increased awareness and screening would save at least 30,000 lives each year. Colonoscopy may also be recommended by your doctor to evaluate for symptoms such as bleeding and chronic diarrhea.

During a colonoscopy, the doctor can also take samples from abnormal-looking tissues. Called a biopsy, this procedure allows the doctor to later look at the tissue with a microscope for signs of disease.