Colonoscopy

Colonoscopy

Author
Jerome D Waye, MD
Section Editor
John R Saltzman, MD, FACP, FACG
Deputy Editor
Shilpa Grover, MD, MPH

Disclosures

COLONOSCOPY OVERVIEW — A colonoscopy is an exam of the lower part of the gastrointestinal tract, which is called the colon or large intestine (bowel). Colonoscopy is a safe procedure that provides information other tests may not be able to give. Patients who require colonoscopy often have questions and concerns about the procedure.

Colonoscopy is performed by inserting a device called a colonoscope into the anus and advanced through the entire colon (figure 1). The procedure generally takes between 20 minutes and one hour.

Other tests that are sometimes used to screen for colon cancer, like virtual colonoscopy (also called CT colonography), are discussed separately. (See “Patient information: Colon cancer screening”.)

More detailed information about colonoscopy is available by subscription. (See “Tests for screening for colorectal cancer: Stool tests, radiologic imaging and endoscopy”.)

REASONS FOR COLONOSCOPY — The most common reasons for colonoscopy are to evaluate the following:

As a screening exam for colon cancer
Rectal bleeding
A change in bowel habits, like persistent diarrhea
Iron deficiency anemia (a decrease in blood count due to loss of iron)
A family history of colon cancer
As a follow-up test in people with colon polyps or colon cancer
Chronic, unexplained abdominal or rectal pain
An abnormal X-ray exam, like a barium enema or CT scan
COLONOSCOPY PREPARATION — Before colonoscopy, your colon must be completely cleaned out so that the doctor can see any abnormal areas. To clean the colon, you will take a strong laxative and empty your bowels the night before your test.

Your doctor’s office will provide specific instructions about how you should prepare for colonoscopy. Be sure to read these instructions ahead of time so you will be prepared for the prep. If you have questions, call the doctor’s office in advance.

You will need to avoid solid food for at least one day before the test. You should also drink plenty of fluids on the day before the test. You can drink clear liquids up to several hours before your procedure, including:

Water
Clear broth (beef, chicken, or vegetable)
Coffee or tea (without milk)
Ices
Gelatin (avoid red gelatin)
The day or night before the colonoscopy, you will take a laxative in two parts:

A pill that you take by mouth
A powder that is mixed with water
The most common laxative treatment is called Go-Lytely® or Half-Lytely®. You can add a flavoring (included), which, unfortunately, only partially hides the unpleasant taste. Most doctors do not recommend that you add other flavorings to the solution.

Refrigerating the solution can make it easier to drink. Drinking this solution may be the most unpleasant part of the exam. You will begin to have watery diarrhea within a short time after drinking the solution. If you become nauseated or vomit while drinking the solution, call your doctor or nurse for instructions. (See “Bowel preparation for colonoscopy”.)

Medicines — You can take most prescription and nonprescription medicines right up to the day of the colonoscopy. Your doctor should tell you what medicines to stop. You should also tell the doctor if you are allergic to any medicines.

Some medicines increase the risk of heavy bleeding if you have a biopsy during the colonoscopy. Ask your doctor how and when to stop these medicines, including warfarin/Coumadin® and clopidogrel/Plavix®.

Transportation home — You will be given a sedative (a medicine to help you relax) during the colonoscopy, so you will need someone to take you home after your test. Although you will be awake by the time you go home, the sedative medicines cause changes in reflexes and judgment that can interfere with your ability to make decisions, similar to the effect of alcohol.

WHAT TO EXPECT — Before the test, a doctor will review the test, including possible complications, and will ask you to sign a consent form.

The nurse will start an IV line in your hand or arm. Your blood pressure and heart rate will be monitored during the test.

THE COLONOSCOPY PROCEDURE — You will be given fluid and medicines through an IV line. Many people sleep during the test, while others are very relaxed, comfortable, and generally not aware.

The colonoscope is a flexible tube, approximately the size of the index finger. The scope pumps air into the colon to inflate it and allow the doctor to see the entire lining. You might feel bloating or gas cramps as the air opens the colon. Try not to be embarrassed about passing this gas, and let your doctor know if you are uncomfortable.

During the procedure, the doctor might take a biopsy (small pieces of tissue) or remove polyps. Polyps are growths of tissue that can range in size from the tip of a pen to several inches. Most polyps are benign (not cancerous). However, some polyps can become cancerous if allowed to grow for a long time. Having a polyp removed does not hurt. (See “Patient information: Colon polyps” and “Endoscopic removal of large colonic polyps”.)

RECOVERY FROM COLONOSCOPY — After the colonoscopy, you will be observed in a recovery area until the effects of the sedative medication wear off. The most common complaint after colonoscopy is a feeling of bloating and gas cramps. You may also feel groggy from the sedation medications. You should not return to work or drive that day. Most people are able to eat normally after the test. Ask your doctor when it is safe to restart aspirin and other blood-thinning medications.

COLONOSCOPY COMPLICATIONS — Colonoscopy is a safe procedure, and complications are rare but can occur:

Bleeding can occur from biopsies or the removal of polyps, but it is usually minimal and can be controlled.
The colonoscope can cause a tear or hole in the colon. This is a serious problem, but it does not happen commonly.
It is possible to have side effects from the sedative medicines.
Although colonoscopy is the best test to examine the colon, it is possible for even the most skilled doctors to miss or overlook an abnormal area in the colon.
You should call your doctor immediately if you have any of the following:

Severe abdominal pain (not just gas cramps)
A firm, bloated abdomen
Vomiting
Fever
Rectal bleeding (greater than a few tablespoons)
AFTER COLONOSCOPY — Although many people worry about being uncomfortable during a colonoscopy, most people tolerate it very well and feel fine afterward. It is normal to feel tired afterward. Plan to take it easy and relax the rest of the day.

Your doctor can describe the results of the colonoscopy as soon as it is over. If s/he took biopsies or polyps, you should call for results within one to two weeks.

WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

 

Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient Level Information:

Patient information: Colon cancer screening
Patient information: Colon polyps

Professional Level Information:

Bleeding after colonic polypectomy
Bowel preparation for colonoscopy
Endoscopic diagnosis of inflammatory bowel disease
Endoscopic procedures in patients with disorders of hemostasis
Endoscopic removal of large colonic polyps
Overview of procedural sedation for gastrointestinal endoscopy
Alternatives and adjuncts to moderate procedural sedation for gastrointestinal endoscopy
Screening for colorectal cancer: Strategies in patients at average risk
Sedation-free gastrointestinal endoscopy
Tattooing and other methods for localizing colonic lesions
Tests for screening for colorectal cancer: Stool tests, radiologic imaging and endoscopy
Wireless video capsule endoscopy

The following organizations also provide reliable health information.

National Library of Medicine
(www.nlm.nih.gov/medlineplus/colonoscopy.html)

American Society for Gastrointestinal Endoscopy
(www.asge.org/PatientInfoIndex.aspx?id=382)

REFERENCES
Unger RZ, Amstutz SP, Seo da H, et al. Willingness to undergo split-dose bowel preparation for colonoscopy and compliance with split-dose instructions. Dig Dis Sci 2010; 55:2030.
Crispin A, Birkner B, Munte A, et al. Process quality and incidence of acute complications in a series of more than 230,000 outpatient colonoscopies. Endoscopy 2009; 41:1018.
ASGE Technology Committee, Mamula P, Adler DG, et al. Colonoscopy preparation. Gastrointest Endosc 2009; 69:1201.
Jechart G, Messmann H. Indications and techniques for lower intestinal endoscopy. Best Pract Res Clin Gastroenterol 2008; 22:777.