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A colonoscopy is a procedure that examines the inside of the large intestine (colon) with a colonoscope - a flexible tube with a light and camera on the end. This tube is passed through the rectum and into the large intestine.


The most common reasons for a doctor to prescribe a colonoscopy are:

  • To look for signs of colorectal cancer or polyps (small growths);
    • Colonoscopy is recommended as a routine test for anyone over 50 years of age;
    • If a person has a family history of colorectal cancer or a higher risk for cancer, screenings may be recommended before 50 years of age;
  • Diagnose and possibly treat bleeding and causes of blood in stool;
  • Diagnose the reason for chronic diarrhea;
  • Screen the colon if abnormal results come back from a stool or barium enema test;
  • Diagnose inflammatory bowel disease (IBD);
  • Diagnose the reason for unexplained abdominal pain.


It is very important that the colon be empty (free of stool) before a colonoscopy so that a complete view of the colon can be seen during the procedure. A clear liquid diet will be prescribed for 1 – 2 days prior to the test, which only allows for liquids such as fat-free broth, water, plain coffee or tea, and diet soda. Popsicles or Jello may be allowed, except for flavors that are red in color. Laxatives taken the night before and the morning of the test will ensure the colon is free from any obstructions. All patients will receive specific instructions from their gastroenterologist.

Patients must have a responsible adult available to drive them to and from the colonoscopy appointment and assist them home. Patients will not be able to drive after the test, due to the sedatives they will receive that make them sleepy and comfortable.


Diagram of GI tractThe patient receives sedatives before the procedure. No pain is associated with a colonoscopy.

The gastroenterologist will guide the colonoscope through the colon and take images and videos during the process that he/she can watch on a monitor. The gastroenterologist examines the lining of the colon to look for inflammation, diagnose reasons for abnormal bowel movements, or find signs of cancerous tissue. If diseased tissue is found, the doctor may take biopsy specimens (tiny bits of tissue) or remove polyps (small growths).

Women who are pregnant and people who have abdominal infections or diverticulitis have higher chances of complications from a colonoscopy and should only have a colonoscopy if a doctor deems it necessary.


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


The colon’s lining appears smooth and pink, with no growths or bleeding. The folds are regularly spaced.


Common abnormalities that can be found by colonoscopy include hemorrhoids, polyps, tumors, or inflammation. The lining may appear swollen and red (colitis), which can be caused by an infection or by inflammatory bowel disease (IBD).

Polyp and Tumor Removal

Bleeding therapy

Stent placement

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