Skip to content

Colorectal Cancer Health Center

Font Size

Colonoscopy

How It Feels

The colon prep will cause diarrhea. Some people also have cramping.

During the test, you may feel very sleepy and relaxed from the sedative and pain medicines. You may have cramping or feel brief, sharp pain when the scope is moved or air is blown into your colon. As the scope is moved up the colon, you may feel the need to have a bowel movement and pass gas. If you are having pain, tell your doctor.

The suction machine used to remove stool (feces) and secretions may be noisy but does not cause pain.

You will feel sleepy after the test for a few hours. Many people say they do not remember very much about the test because of the sedative.

After the test, you may have bloating or crampy gas pains and may need to pass some gas. If a biopsy was done or a polyp taken out, you may have traces of blood in your stool (feces) for a few days. If polyps were taken out, your doctor may instruct you to not take aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) for 7 to 14 days.

Risks

There is a small chance for problems from a colonoscopy. The scope or a small tool may tear the lining of the colon or cause bleeding.

After the test

After the test, call your doctor immediately if you:

  • Have heavy rectal bleeding.
  • Have severe belly pain.
  • Develop a fever.
  • Are very dizzy.
  • Are vomiting.
  • Have a swollen and firm belly.

Results

Colonoscopy is a test that allows your doctor to look at the inner lining of your large intestine (rectum and colon). If a sample of tissue (biopsy) was collected during the colonoscopy, it will be sent to a lab for tests.

  • Samples of colon tissue are usually sent to a pathology lab, where they are looked at under a microscope for diseases.
  • Other samples of colon tissue may be sent to a microbiology lab to see whether an infection is present.

Your doctor may be able to tell you the results immediately after the procedure. Other test results are ready in 2 to 4 days. Test results for certain infections may be ready in several weeks.

Colonoscopy
Normal:

The lining of the colon looks smooth and pink, with a lot of normal folds. No growths, pouches, bleeding, or inflammation are present.

Abnormal:

Some abnormal findings of colonoscopy include hemorrhoids (the most common cause of blood in the stool), polyps , cancer , one or more sores (ulcers), pouches in the wall of the colon (diverticulosis), or inflammation. A red, swollen lining of the colon (colitis) may be caused by infection or inflammatory bowel disease (IBD).

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

  • Having a barium enema within a week before the test. Barium can block your doctor's view of the colon.
  • Not doing a good colon prep before the test. If you still have stool (feces) in the colon, your doctor may cancel the test and you will have to reschedule and do the colon prep again.
  • Having a colon that has many turns, past surgery on the colon, or a lot of pain during the test.
  • Taking iron supplements. This may make your stool turn black and make it hard to clean out the colon. Do not take iron supplements for several days before a colonoscopy.
  • Drinking red or purple fluids, such as grape juice or fruit punch.
  • Eating red or purple foods, such as grape ice pops or cherry gelatin.

WebMD Medical Reference from Healthwise

Last Updated: October 30, 2013
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

Today on WebMD

Colorectal cancer cells
The right diagnosis is the most important factor.
man with a doctor
Our health check will steer you in the right direction.
 
sauteed cherry tomatoes
Fight cancer one plate at a time.
bladder cancer x-ray
Do you know the warning signs?
 
bread
ARTICLE
Colon vs Rectal Cancer
VIDEO
 
New Colorectal Treatments
VIDEO
can lack of sleep affect your immune system
FEATURE
 
Cancer Facts Quiz
QUIZ
Virtual Colonoscopy
VIDEO
 
Picture of the Colon
ANATOMY
Vitamin D
SLIDESHOW
 

WebMD Special Sections