Lower GI Endoscopy (Colonoscopy)What is a colonoscopy?
Colonoscopy is a diagnostic procedure that allows the endoscopist to examine the entire length of the large intestine. Colonoscopy can assist in identifying problems with the colon, such as early signs of cancer, inflamed tissue, ulcers, and bleeding. Colonoscopy is also used to screen for colorectal cancer.
A long, flexible, lighted tube (also called a colonoscope), is inserted through the rectum into the colon. In addition to allowing visualization of the internal colon, the colonoscope enables the endoscopist to irrigate, suction, inflate with air, and access the bowel with surgical instruments. During a colonoscopy, the endoscopist may remove tissue for further examination and treat any problems that are discovered.
Other related procedures that may be used to assess problems of the colon include abdominal x-ray, computed tomography (CT scan) of the abdomen, abdominal ultrasound, barium enema, and sigmoidoscopy.
The procedure can be done either in the doctor's office or in a special procedure room of a local hospital. An intravenous (IV) line will be started in a vein in the arm. The patient is generally given a sedative and a pain-killer through the IV line.
During the colonoscopy, the patient will be asked to lie on his/her left side with his/her knees drawn up towards the abdomen. The doctor begins the procedure by inserting a lubricated, gloved finger into the anus to check for any abnormal masses or blockage. A thin, well-lubricated colonoscope will then be inserted into the anus and it will be gently advanced through the colon. The lining of the intestine will be examined through the scope. Air will be pumped through the colonoscope to help clear the path or open the colon to enable mucosal (lining) inspection. If there are excessive secretions, stool, or blood that obstruct the viewing, they will be suctioned out through the scope. The doctor may press on the abdomen or ask the patient to change his/her position in order to advance the scope through the colon.
The entire length of the large intestine can be examined in this manner. If suspicious growths are observed, tiny biopsy forceps or brushes can be inserted through the colonoscope and tissue samples can be obtained. Small polyps can also be removed through the colonoscope. After the procedure, the colonoscope is slowly withdrawn and the instilled air is allowed to escape. The anal area is then cleansed with tissues.
The procedure may take anywhere from 30 minutes to over an hour depending on how easy it is to advance the scope through bends in the colon. Colonoscopy can be a long and uncomfortable procedure, and the bowel cleaning preparation may be tiring and can produce diarrhoea and cramping. During the colonoscopy, the sedative and the pain medications will keep the patient very drowsy and relaxed. Most patients complain of minor discomfort and pressure from the colonoscope moving inside.
Reasons for the Procedure
A colonoscopy may be used to examine colon polyps, tumours, ulceration, inflammation, diverticula (pouches), strictures (narrowing), and foreign objects within the colon. It may also be used to determine the cause of unexplained chronic diarrhoea or gastrointestinal bleeding or to evaluate the colon after cancer treatment.
Colonoscopy may be indicated when the results of a barium enema and/or sigmoidoscopy warrant further examination of the colon.
- persistent bleeding after biopsy
- peritonitis (inflammation of the lining of the abdominal cavity)
- perforation of the intestinal wall (rare)