Author: OncoLink Team
Last Reviewed: April 12, 2022

What is a colonoscopy?

A colonoscopy is a medical test that looks at the lower GI tract. It uses a thin tube (endoscope) with a camera and other tools attached to the end of it. Your GI tract is a long tube and the endoscope (or "scope") can easily pass through it. Using an endoscope, your provider can assess the health of the rectum, colon, and small intestines. Colonoscopy is used to look for polyps which are precancerous or cancerous lesions. It is also used for patients who have rectal bleeding or abnormal bowel movements to identify the causes of these problems. Most colonoscopies are done as outpatient procedures.

How do I prepare for a colonoscopy?

You will be given instructions to follow prior to the test being done. It is important to follow these instructions to entirely clear out the bowel. Call your provider if you have any questions. In general:

  • You will need to maintain a clear liquid diet for 1-2 days and take a laxative 24 hours prior to the procedure. This is to ensure that all stool is out of the bowel and that the provider can see the lining of the intestine clearly.
  • Because sedation will be used, you must fast (not eat) for 8 hours prior to the procedure.
  • Be sure to discuss any allergies or heart and lung problems you have with the provider, as this can impact the types of medications that can be used for sedation.
  • If you are on blood thinners, your provider will likely have you stop them several days in advance.

How is this test performed?

An intravenous line (IV) will be placed. You will be asked to lie on your side on a table or gurney. You will be given a sedative through your IV to help you relax. The provider will insert the scope gently into the anus and push it through to the end of the lower bowel. The provider then slowly removes the scope, examining the bowel as the scope passes through.

The endoscope has a light, a camera, and biopsy tools attached to it, in case a biopsy is needed. The test takes about 30-60 minutes. Be prepared to be at the endoscopy facility for several hours. This is because you will need to be monitored after the test, until you are completely awake. Likely, you will not remember having the test done.

What to expect after your colonoscopy?

You will not be allowed to drive yourself home after the test. You may feel bloated, or have a small amount of bleeding and slight discomfort in the anal area, which will resolve within a few days. A small amount of blood in your stool after the procedure is normal. You should also expect to return to your normal bowel habits in 2-3 days.

How do you receive the results of your colonoscopy?

The provider will typically talk to you about the findings of the test before you go home. Any biopsies that were taken will be sent to a pathologist to be reviewed. The results of this are usually available in 7-10 days. Your care provider will be able to discuss these results with you.

When to contact your provider:

  • Severe abdominal pain. If your abdomen becomes bigger and hard to the touch, this can be a sign of a tear or perforation in your colon and is a medical emergency.
  • Bright red blood in two or more bowel movements or consistent leaking of bright red blood.
  • Nausea and vomiting with blood in it.
  • Fever (temperature >100.4°F (38°C).


MedLine Plus. Colonoscopy.

Society Of American Gastrointestinal And Endoscopic Surgeons (SAGES). Colonoscopy Patient Information from Sages.


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