Colonoscopy is a procedure in which a doctor uses a colonoscope or scope, to look inside your rectum and colon. Colonoscopy can show irritated and swollen tissue, ulcers, polyps, and cancer.
Your doctor will recommend screening for colon and rectal cancer —also called colorectal cancer—starting at age 45 if you don’t have health problems or risk factors that make you more likely to develop colon cancer.
You have risk factors for colorectal cancer if you:
- are male
- are African American
- or someone in your family has had polyps or colorectal cancer
- have a personal history of inflammatory bowel disease, such as ulcerative colitis and Crohn’s disease
- have Lynch syndrome , or another genetic disorder that increases the risk of colorectal cancer
- have other factors, such as that you weigh too much or smoke cigarettes
If you are more likely to develop colorectal cancer, your doctor may recommend screening at a younger age, and more often.
If you are older than age 75, talk with your doctor about whether you should be screened. For more information, read the current colorectal cancer screening guidelines from the U.S. Preventive Services Task Force (USPSTF).
A colonoscopy can help a doctor find the cause of symptoms, such as
- bleeding from your anus
- changes in your bowel activity, such as diarrhea
- pain in your abdomen
- unexplained weight loss
Doctors also use colonoscopy as a screening tool for colon polyps and cancer. Screening is testing for diseases when you have no symptoms. Screening may find diseases at an early stage, when a doctor has a better chance of curing the disease.
A doctor performs a colonoscopy in a hospital or an outpatient center. A colonoscopy usually takes 30 to 60 minutes.
A health care professional will place an intravenous (IV) needle in a vein in your arm or hand to give you sedatives, anesthesia, or pain medicine, so you won’t be aware or feel pain during the procedure. The health care staff will check your vital signs and keep you as comfortable as possible.
For the procedure, you’ll lie on a table while the doctor inserts a colonoscope through your anus and into your rectum and colon. The scope inflates your large intestine with air for a better view. The camera sends a video image to a monitor, allowing the doctor to examine your large intestine.
The doctor may move you several times on the table to adjust the scope for better viewing. Once the scope reaches the opening to your small intestine, the doctor slowly removes the scope and examines the lining of your large intestine again.
During the procedure, the doctor may remove polyps and will send them to a lab for testing. You will not feel the polyp removal. Colon polyps are common in adults and are harmless in most cases. However, most colon cancer begins as a polyp, so removing polyps early helps to prevent cancer.
If your doctor finds abnormal tissue, he or she may perform a biopsy. You won’t feel the biopsy.
After a colonoscopy, you can expect the following:
- The anesthesia takes time to wear off completely. You’ll stay at the hospital or outpatient center for 1 to 2 hours after the procedure.
- You may feel cramping in your abdomen or bloating during the first hour after the procedure.
- After the procedure, you—or a friend or family member—will receive instructions on how to care for yourself after the procedure. You should follow all instructions.
- You’ll need your pre-arranged ride home, since you won’t be able to drive after the procedure.
- You should expect a full recovery and return to your normal diet by the next day.
After the sedatives or anesthesia wear off, your doctor may share what was found during the procedure with you or, if you choose, with a friend or family member.
If the doctor removed polyps or performed a biopsy, you may have light bleeding from your anus. This bleeding is normal. A pathologist will examine the biopsy tissue, and results take a few days or longer to come back. A health care professional will call you or schedule an appointment to go over the results.