Colonoscopy is the visual examination of the large intestine (colon) using a lighted, flexible fiber-optic or video endoscope.  
The colon begins in the right-lower abdomen and looks like a big question mark as it moves up and around the abdomen, ending in the rectum.  It is 5 to 6 feet long.  The colon has a number of functions including withdrawing water from the liquid stool that enters it so that a formed stool is produced.


Reasons For The Exam
There are many types of problems that can occur in the colon. Medical history, the physical exam, laboratory tests and x-rays can provide information useful in making a diagnosis. Directly viewing the inside of the colon by colonoscopy is usually the best exam.  

Colonoscopy is used for:

  • Colon cancer—a serious but highly curable malignancy

  • Polyps—fleshy tumors which usually are the forerunners of colon cancer

  • Colitis (Ulcerative or Crohn's)—chronic, recurrent inflammation of the colon

  • Diverticulosis and Diverticulitis—pockets along the intestinal wall that develop over time and can become infected

  • Bleeding lesions—bleeding may occur from different points in the colon

  • Abdominal symptoms, such as pain or discomfort, particularly if associated with weight loss or anemia

  • Abnormal barium x-ray exam

  • Chronic diarrhea, constipation, or a change in bowel habits

  • Anemia

The Procedure
Colonoscopy is usually performed on an outpatient basis.  The patient is mildly sedated, the endoscope is inserted through the anus and moved gently around the bends of the colon.  If a polyp is encountered, a thin wire snare is used to lasso it. Electrocautery (electrical heat) is applied to painlessly remove it.  Other tests can be performed during colonoscopy, including biopsy to obtain a small tissue specimen for microscopic analysis.

The procedure takes 15 to 30 minutes and is seldom remembered by the sedated patient.  A recovery area is available to monitor vital signs until the patient is fully awake. It is normal to experience mild cramping or abdominal pressure following the exam. This usually subsides in an hour or so.

Benefits
A colonoscopy is performed to identify and/or correct a problem in the colon. The test enables a diagnosis to be made and specific treatment can be given. If a polyp is found during the exam, it can be removed at that time, eliminating the need for a major operation later.  If a bleeding site is identified, treatment can be administered to stop the bleeding.  Other treatments can be given through the endoscope when necessary.