A colonoscopy is a diagnostic test done to detect abnormalities in the large intestine, colon and rectum. 

Why Colonoscopy is performed?

Colonoscopy is done to:

• Investigate intestinal signs and symptoms- A colonoscopy can help the doctor explore possible causes of abdominal pain, rectal bleeding, chronic constipation, chronic diarrhea and other intestinal problems.

• As a screening for colon cancer 

• Look for polyps- If patient had polyps before, the doctor may recommend a follow-up colonoscopy to look for and remove any additional polyps. This is done to reduce the risk of colon cancer.

What are the risks of Colonoscopy ?

A colonoscopy have few risks:

• Reaction to the sedative used during the test
• Bleeding from the site where a tissue sample was taken for biopsy or a polyp or other abnormal tissue was removed
• A tear in the colon or rectum wall  

Preparations for Colonoscopy

Before the start of colonoscopy, patient need to empty the colon. Any residue in colon may obscure the view of the colon and rectum during the exam. This is done by dietary management a day prior to the procedure, use of laxative and / or using enema to clear the colon. Certain medications may have to be modified or stopped altogether based on instructions from the Doctor 

During the procedure

During a colonoscopy, a mild sedative is given. In other cases, the sedative is combined with an intravenous pain medication to minimize any discomfort. Patient will begin the test lying on side on the exam table, usually with the knees drawn toward the chest. The doctor will insert a colonoscope into rectum.

The scope which is long enough to reach the entire length of the colon, contains a light and a tube that allows the doctor to pump air or carbon dioxide into the colon. The air or carbon dioxide inflates the colon, which provides a better view of the lining of the colon. When the scope is moved or air is introduced, patient may feel abdominal cramping or the urge to have a bowel movement. The colonoscope contains a tiny video camera at its tip. The camera sends images to an external monitor so that the doctor can study the inside of the colon.

The doctor can also insert instruments through the channel to take tissue samples for biopsies or remove polyps or other areas of abnormal tissue. A colonoscopy typically takes about 30 to 60 minutes.

After the procedure

After the exam, it takes about an hour to begin to recover from the sedative. Patient will need someone to take him/her home because it can take up to a day for the full effects of the sedative to wear off. A patient has to take a day off and cannot drive or return to work. If the doctor removed a polyp during the colonoscopy, patient may be advised to eat a special diet temporarily. Patient may feel bloated or pass gas for a few hours after the exam, as patient clear the air from colon. Walking may help relieve any discomfort.Patient may also notice a small amount of blood with the first bowel movement after the exam. Usually this isn't cause for alarm. Consult the doctor if bleeding continues or blood clots or if have persistent abdominal pain or a fever.