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Patient education: Colonoscopy (The Basics)

Patient education: Colonoscopy (The Basics)

What is a colonoscopy? — A colonoscopy is a test that looks at the inner lining of a person's large intestine. The large intestine is also called the colon (figure 1).

Often, people have a colonoscopy as a screening test to check for polyps or for cancer in the colon or rectum. Polyps are growths in the colon that might turn into cancer. If you have polyps, the doctor can usually take them out during the colonoscopy. Taking polyps out lowers your chances of getting cancer. People can also have a colonoscopy if they have any of the symptoms listed below.

Cancer screening tests are tests that are done to try and find cancer early, before a person has symptoms. Cancer that is found early often is small and can be cured or treated easily.

Doctors can use 5 or 6 different tests to screen for colon cancer. But most doctors think that colonoscopy is the best test to screen for colon cancer.

When should I have colon cancer screening? — Doctors recommend that most people begin having colon cancer screening at age 45. Some people have an increased chance of getting colon cancer, because of a strong family history or certain medical conditions. These people might begin screening at a younger age.

What are other reasons my doctor might order a colonoscopy? — Your doctor might order a colonoscopy if you have:

Blood in your bowel movements

A change in your bowel habits

A condition called anemia that can make you feel tired and weak

Long-term belly or rectal pain that you cannot explain

Abnormal results from a different type of colon test

A history of colon cancer or polyps in your colon

What should I do before a colonoscopy? — Your doctor will give you instructions about what to do before a colonoscopy. They will tell you what foods you can and cannot eat. They will also tell you if you need to stop taking any of your usual medicines beforehand. Make sure to read the instructions as soon as you get them. You might have to stop some medicines up to a week before the test.

The colon needs to be cleaned out before a colonoscopy. Your doctor will give you a special drink that causes watery diarrhea. It is important to drink all of it to make sure your colon is clean. If your colon is clean, your doctor will get a better look at the inside lining of the colon. A clean colon also makes the test easier to do and more comfortable. Let your doctor know if you have trouble getting ready for your colonoscopy.

What happens during a colonoscopy? — Your doctor will give you medicine to make you feel relaxed. Then they will put a thin tube with a camera and light on the end into your anus and up into the rectum and colon (figure 2). Your doctor will look at the inside lining of the whole colon.

During the procedure, your doctor might do a test called a biopsy. During a biopsy, a doctor takes a small piece of tissue from the colon. Then they look at the tissue under a microscope to see if it has cancer. Your doctor might also remove growths that they see in the colon. You will not feel it if the doctor takes a biopsy or removes a growth.

What happens after a colonoscopy? — Your doctor will give you instructions about what to do after a colonoscopy. Most people can eat as usual. But most doctors recommend that people do not drive or go to work for the rest of the day. Your doctor will tell you when to start taking any medicines you had to stop before the test.

When should I call my doctor or nurse? — Call your doctor or nurse immediately if you have any of the following problems after your colonoscopy:

Belly pain that is much worse than gas pain or cramps

A bloated and hard belly



A lot of bleeding from your anus

More on this topic

Patient education: Colon and rectal cancer screening (The Basics)
Patient education: Colon polyps (The Basics)
Patient education: Cancer screening (The Basics)
Patient education: Bloody stools (The Basics)
Patient education: Gas and bloating (The Basics)
Patient education: Stomach ache and stomach upset (The Basics)
Patient education: Anemia caused by low iron (The Basics)
Patient education: Colon and rectal cancer (The Basics)

Patient education: Colonoscopy (Beyond the Basics)
Patient education: Screening for colorectal cancer (Beyond the Basics)
Patient education: Colon polyps (Beyond the Basics)

This topic retrieved from UpToDate on: Jan 01, 2023.
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