Author: OncoLink Team
Last Reviewed: April 12, 2024

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 look at your rectum, colon, and small intestines. A colonoscopy is used to look for polyps which are precancerous or cancerous lesions (an area of damaged tissue). It is also used for patients who have rectal bleeding or abnormal bowel movements to find the causes of these problems. Most colonoscopies are done as outpatient procedures. In some cases, you may be able to get a virtual colonoscopy. This uses CT to look at your colon. Your provider will tell you if this is an option for you.

How do I prepare for a colonoscopy?

You will be given instructions to follow before the test. It is important to follow these instructions to empty your bowel. Call your provider if you have any questions. In general:

  • You will need to be on a clear liquid diet for 1-2 days and take a laxative 24 hours before the procedure. This helps make sure all stool is out of the bowel and that the provider can see the lining of the intestine clearly.
  • Because sedation (medication used to help you feel calm and sleepy during a procedure) will be used, you can not eat for 8 hours before the procedure.
  • Talk to your provider about any allergies or heart and lung problems you have, 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 before your procedure.

How is this test done?

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. Your provider will put the scope gently into the anus and push it through to the end of the lower bowel. Your provider then slowly removes the scope, looking at the bowel as the scope passes through. 

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

What to expect after a 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 get better within a few days. A small amount of blood in your stool after the procedure is normal. You can expect to return to your normal bowel habits in 2-3 days. 

How do I get the results of my colonoscopy?

Your provider will 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 ready in 7-10 days. Your provider will be able to talk about these results with you. 

When to contact your provider:

Contact your provider if you have:

  • 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. 2024.

Society Of American Gastrointestinal And Endoscopic Surgeons(SAGES)Colonoscopy Patient Information from Sages. 2015.

National Cancer Institute. NCI Dictionaries. Retrieved 2024.

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