Colonoscopy

Answer 1

Definition

A colonoscopy is an internal examination of the colon (large intestine) and rectum, using an instrument called a colonoscope.

How the test is performed

The colonoscope has a small camera attached to a flexible tube. Unlike sigmoidoscopy, which can only reach the lower third of the colon, colonoscopy examines the entire length of the colon.

You will lie on your left side with your knees drawn up toward the chest. After you have received a sedative and pain reliever, the colonoscope is inserted through the anus and gently advanced to the lowest part of the small bowel.

Air will be inserted through the scope to provide a better view. Suction may be used to remove fluid or stool.

Because the health care provider gets a better view as the colonoscope is pulled back out, a more careful examination is done while the scope is being pulled out. Tissue samples may be taken with tiny biopsyforceps inserted through the scope. Polyps may be removed with electrocauterysnares, and photographs may be taken.

Specialized procedures, such as laser therapy, may also be done.

How to prepare for the test

You will need to completely cleanse the bowel. Your health care provider will give you instructions for doing this. This may include a combination of enemas, not eating solid foods for 2 or 3 days before the test, and taking laxatives. You will usually be told to stop taking aspirin, ibuprofen, naproxen, or other blood-thinning medications for several days before the test.

You will be asked to drink plenty of clear liquids for 1 - 3 days before the test. Examples of clear liquids are: fat-free bouillon or broth, water, clean coffee or tea, strained fruit juices, sports drinks, and Gelatin.

Unless otherwise instructed, continue taking any regularly prescribed medication. Stop taking iron preparations a few weeks before the test, unless otherwise instructed by your health care provider. Iron residues produce a dark black stool, which makes the view inside the bowel less clear.

People with some heart valve diseases may receive antibiotics before and after the test to prevent infection. Outpatients must plan to have someone take them home after the test, because they will be woozy and unable to drive.

Infants and children:

The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust. For general information regarding how you can prepare your child, see the following topics:

• Infant test or procedure preparation (birth to 1 year)
• Toddler test or procedure preparation (1 to 3 years)
• Preschooler test or procedure preparation (3 to 6 years)
• School age test or procedure preparation (6 to 12 years)
• Adolescent test or procedure preparation (12 to 18 years)

How the test will feel

The sedative and pain medication will relax you and make you feel drowsy. Many patients do not remember having the colonoscopy. A rectal examination usually is done before the test to widen (dilate) the rectum and make sure there are no major obstructions. You may have the urge to defecate when the rectal exam is performed or as the colonoscope is inserted.

You may feel pressure as the scope moves inside. You may feel brief cramping and gas pains as air is inserted or the scope advances. Passing gas is necessary and should be expected.

You can reduce discomfort by taking slow, deep breaths. This will also help relax the abdominal muscles. Mild abdominal cramping and considerable passing of gas may occur after the exam. Sedation should wear off in a few hours. Because of the sedation, you may not feel any discomfort and may have no memory of the test.

Why the test is performed

Colonoscopy may be used for the following reasons:

• Anemia (usually when no other cause has been found)
• Blood in the stool, or black, tarry stools
• Symptoms such as abdominal pain, changes in bowel movements, or weight loss
• Abnormal changes (such as polyps) found on sigmoidoscopy or x-ray tests (CT scan or barium enema)
• Inflammatory bowel disease (ulcerative colitis and Crohn's disease)
• Follow-up of a previous finding, such as polyps or colon cancer
• Screen for colorectal cancer

Normal Values

Normal findings are healthy intestinal tissues.

What abnormal results mean

• Diverticulosis (abnormal pouches on the lining of the intestines, which increase with age)
• Inflammatory bowel disease
• Lower gastrointestinal (GI) bleeding
• Polyps (which can be removed through the colonoscope during the exam)
• Tumor

Additional conditions under which the test may be performed:

• Cytomegalovirus, gastroenteritis, or colitis
• Colon cancer screening
• Colorectal polyps
• Ischemic colitis
• Pseudomembranous colitis

What the risks are

• Bowel perforation (a hole or tear in the wall of the colon), requiring a repair operation (between 1 and 3 times out of 1,000 tests)
• Heavy or persistent bleeding from biopsy or polyp-removal sites (about 7 times out of 1,000 tests in which polyp-removal is done -- the larger the polyp, the higher the risk)
• Adverse reaction to sedative medication, causing breathing problems or low blood pressure (6 to 7 out of 10,000 tests)
• Infection requiring antibiotic therapy (very rare)
• Nausea, vomiting, bloating, or rectal irritation caused by medicines, taken by mouth, that cleanse the bowel

Special considerations

You must sign an informed consent form. Several hours of rest is recommended after the test. To replace fluids lost because of laxatives and fasting, drink plenty of liquids after the test.

References

Pasricha PJ. Gastrointestinal endoscopy. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 136.

Answer 2

A colonoscopy is a procedure where a flexible tube with a camera is inserted into the rectum to examine the large intestine for abnormalities such as polyps or signs of colorectal cancer. It is commonly used for screening and diagnosing various conditions like inflammatory bowel disease or gastrointestinal bleeding. Patients are usually sedated during the procedure to minimize discomfort.

Answer 3

Definition

A colonoscopy is an internal examination of the colon (large intestine) and rectum, using an instrument called a colonoscope.

The colonoscope has a small camera attached to a flexible tube that can reach and examine the entire length of the colon.

How the test is performed

You will usually be given medicine into a vein to help you relax and not feel any discomfort. You will be awake during the test and may even be able to speak, but you will likely not remember anything.

You will lie on your left side with your knees drawn up toward your chest. The colonoscope is inserted through the anus. It is gently moved into the beginning of the large bowel and slowly moved as far as the lowest part of the small intestine.

Air will be inserted through the scope to provide a better view. Suction may be used to remove fluid or stool.

Because the health care provider gets a better view as the colonoscope is pulled back out, a more careful examination is done while the scope is being pulled out. Tissue samples may be taken with tiny biopsyforceps inserted through the scope. Polyps may be removed with snares, and photographs may be taken.

Specialized procedures, such as laser therapy, may also be done.

How to prepare for the test

You will need to completely cleanse your intestines. If you do not do this, a problem in your large intestine that needs to be treated may be missed during the test.

Your health care provider will give you instructions for cleansing your intestines. This may include enemas, not eating solid foods for 2 or 3 days before the test, and taking laxatives.

You will be asked to drink plenty of clear liquids for 1 - 3 days before the test. Examples of clear liquids are:

• Clean coffee or tea
• Fat-free bouillon or broth
• Gelatin
• Sports drinks
• Strained fruit juices
• Water

You will usually be told to stop taking aspirin, ibuprofen, naproxen, or other blood-thinning medications for several days before the test. Unless you are told otherwise, continue taking your other medicines.

Stop taking iron pills or liquids a few weeks before the test, unless your health care provider tells you otherwise. Iron can produce a dark black stool, which makes the view inside the bowel less clear.

How the test will feel

Because of the medicines that make you sleepy, you may not feel any discomfort and may have no memory of the test.

You may feel pressure as the scope moves inside. You may feel brief cramping and gas pains as air is inserted or the scope advances. Passing gas is necessary and should be expected.

You may have mild abdominal cramping and pass a lot of gas after the exam.

Why the test is performed

Colonoscopy may be used for the following reasons:

• Abdominal pain, changes in bowel movements, or weight loss
• Abnormal changes (such as polyps) found on sigmoidoscopy or x-ray tests (CT scan or barium enema)
• Anemia due to low iron (usually when no other cause has been found)
• Blood in the stool, or black, tarry stools
• Follow-up of a past finding, such as polyps or colon cancer
• Inflammatory bowel disease (ulcerative colitis and Crohn's disease)
• Screening for colorectal cancer

Normal Values

Normal findings are healthy intestinal tissues.

What abnormal results mean

• Abnormal pouches on the lining of the intestines, called diverticulosis
• Areas of bleeding
• Cancer in the colon or rectum
• Colitis (a swollen and inflamed intestine) due to Crohn's disease, ulcerative colitis, infection, or lack of blood flow
• Small growths called polyps that stick out of the lining of your colon (which can be removed through the colonoscope during the exam)

What the risks are

• Heavy or persistent bleeding from biopsy or polyp-removal sites
• Hole or tear in the wall of the colon that requires a repair operation
• Infection needing antibiotic therapy (very rare)
• Reaction to sedative medication, causing breathing problems or low blood pressure

Special considerations

After the test, you will feel sleepy for a period of time. You may have a headache or feel sick to your stomach or bloated, but this is not common. You may pass a lot of gas.

You should be able to go home about 1 hour after the test. You must plan to have someone take you home after the test, because you will be woozy and unable to drive. The nurses and doctors will not let you leave until someone arrives to help you.

When you are home:

• Drink plenty of liquids. Eat a healthy meal to restore your energy.
• You should be able to return to your regular activities the next day.
• Avoid driving, operating machinery, drinking alcohol, and making legal decisions for at least 24 hours after the test.

References

Kimmey MB. Complications of gastrointestinal endoscopy. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa: Saunders Elsevier;2010:chap 40.

Pasricha PJ. Gastrointestinal endoscopy. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 136.

Reviewed By

Review Date: 11/09/2011

George F. Longstreth, MD, Department of Gastroenterology, Kaiser Permanente Medical Care Program, San Diego, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.