Colonoscopy

A colonoscopy is an outpatient procedure used to see the inside of the colon.


Anatomy
The colon is the part of the large intestine that extends from the small intestine to the anus. The colon extracts water from undigested food and stores the waste, which is excreted through stools.

Purpose
The purpose of the procedure is to allow the doctor to directly see the inside of the colon. Other colon tests, such as ultrasound (using sound waves to create pictures of internal body parts) or barium enema (an X-ray of the bowel after the doctor inserts barium, a contrast dye, into the rectum) can't provide this vital information.

Indications
Colonoscopy may be recommended in a variety of situations. For example, a doctor may use the procedure to:
do a biopsy (take a sample of tissue cells for further analysis)
remove polyps (growths) in the colon
diagnose and monitor inflammatory bowel disease (a chronic disorder in which the bowel becomes inflamed) or other types of inflammation in the colon
evaluate possible causes for iron-deficiency anemia, prolonged diarrhea, changes in bowel habits, rectal bleeding or abdominal pain
identify or treat narrowing of the intestine
remove foreign objects from the colon
follow up after other types of colon exams, such as an abnormal barium enema
monitor benign (noncancerous) polyps or colorectal cancer
treat certain sources of bleeding, such as ulcerations (open sores)
Beginning at age 50, sigmoidoscopy (examination of the rectum, the end of the large intestine and lower part of the colon) is typically recommended every three to five years to screen for colorectal cancer. This test isn't as extensive as a colonoscopy. Colonoscopy may be recommended as a screening test for certain people, however, including those who have a strong family history of colorectal cancer, especially at an early age. Ask your doctor which procedure would be best for you.


Patient preparation
The doctor will review your medical history, including your current medications and allergies, and do a physical exam. He or she will discuss the risks and benefits of the procedure, and you'll be asked to sign an informed consent document.
Most medication can be continued as usual. Some may interfere with your preparation for the procedure, however. Make sure your doctor knows what medications you're taking, especially aspirin, blood thinners (Coumadin, for example), vitamins, iron products, and herbal or dietary supplements. It's also important to tell the doctor if you normally take antibiotics before dental procedures.

For accurate results, the colon must be completely clean. Your doctor will give you specific dietary dos and don'ts, as well as other special instructions to follow. You may need to:

follow a clear liquid diet for 24 to 48 hours before the test
avoid eating or drinking after midnight the night before the test
take a laxative such as magnesium citrate or GoLYTELY solution to clear your bowels the night before the procedure
have an enema to stimulate a bowel movement the night before or morning of the test
Just before the procedure, you'll probably receive a mild sedative through an IV to keep you comfortable and help you relax.


Procedure
Although every surgery has its own standard procedure, your individual health history could play a role in any variation to the procedure. Discuss these issues with your doctor.
Colonoscopy is usually done on an outpatient basis. Depending on the exact procedure, your medical history and current health status, it may be done as an inpatient. Often, the procedure is done by a specialist, such as a gastroenterologist.

As you lie on your left side, a colonoscope (a hollow, flexible tube equipped with a camera lens and light) will be passed into the anus and moved slowly up the colon. As the doctor examines the walls of the colon, air will be inserted through the colonoscope to allow the doctor to view the colon. Various tools can be used inside the colonoscope for diagnosis and treatment. For example, special forceps may be passed through the colonoscope to allow the doctor to biopsy any suspicious lesions. At some point, you may feel pressure, bloating or cramping.

As the colonoscope is withdrawn, the doctor will examine the colon lining again for any abnormalities.

The procedure typically takes between 30 and 60 minutes.


Postprocedure care
You may not be alert after the procedure, so have someone drive you home. Air that reached the colon during the colonoscopy may cause cramping or bloating. This usually disappears once you begin to pass gas. Most people are able to eat soon after the procedure. The doctor may impose dietary restrictions, however. He or she may also place limits on activity, depending on what procedures were done during the colonoscopy. If you had any surgical procedures, such as a biopsy or a polyp removal, you may notice a small amount of blood in your stool.
Call the doctor right away if you develop:

abdominal pain or bloating with an inability to pass gas
fever
chills
profuse rectal bleeding
other symptoms as described by your doctor

Benefits
Colonoscopy allows a doctor to clearly see the entire colon, which can't be done with other procedures. This visual exam helps the doctor accurately diagnose certain diseases. Biopsy can be done through the scope to help diagnose other diseases.

Risks
Complications are rare, but may include:
a reaction to the sedative medication
irritation at the site of the IV
bleeding from the site of a biopsy or removed polyp
a perforation (tear) of the bowel wall, which would require surgery and may lead to infection or hemorrhage (heavy bleeding)

Considerations
Colonoscopy isn't appropriate if:
you have acute colitis (inflammation of the colon) or diverticulitis (inflammation of diverticula -- a small, protruding pouch that can develop in the gastrointestinal tract -- usually in the colon)
you have a perforated cavity or organ
there's an infection in the abdominal cavity
you had a recent heart attack or abdominal surgery
you're pregnant and nearing your due date
you're bleeding heavily from the rectum

Research
Virtual colonoscopy (computed tomographic or CT colonography) is being tested as another tool for use in the early detection of colorectal cancer. Preparation is the same as the conventional colonoscopy, but the virtual procedure allows the doctor to examine the colon with detailed computed tomography scans (computer-generated, cross-sectional pictures of internal body parts), rather than using a scope inside the colon. It's done without sedation, so you can leave as soon as the test is completed.
During the procedure, a tube is inserted through the rectum and the colon is filled with air. You may be given an intravenous medication to minimize muscle spasms and abdominal discomfort. If polyps are found during the exam, conventional colonoscopy must be done to remove them. The virtual colonoscopy may be more accurate in identifying the location of polyps and determining their size and shape, but smaller polyps may not be seen as well.

Currently, virtual colonoscopy isn't recommended by the American Cancer Society for early detection of colorectal cancer. Further studies are underway to improve the test and determine its accuracy.