What Is a Colonoscopy?
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A colonoscopy is a procedure that allows your health care provider to check the inside of your colon or large intestine. The procedure is done using a long flexible tube, called a colonoscope. The colonoscope has a tiny camera and light on one end that is put in your rectum and moved into your colon. The camera sends images back to your provider for evaluation and can show inflamed tissue, polyps, ulcers and other abnormal growths. Your provider may remove tissue or abnormal growths for further examination.
What does the colon do and how many different sections are there?
What happens during a colonoscopy?
At what age should I have my first colonoscopy and how often do I need one?
Are there alternative procedures or tests to a colonoscopy that provide the same results?
What are the associated risks and complications with a colonoscopy?
What does the colon do and how many different sections are there?
The colon, or large intestine, is the last part of your digestive system. It absorbs water to change waste from liquid to solid stool. The large intestine is about five feet long in adults and has four different sections:
- Ascending colon: Extends upward on the right side of your belly
- Transverse colon: Extends from the ascending colon across your body to the left side of your belly
- Descending colon: Extends from the transverse colon down the left side of your belly
- Sigmoid colon: Extends from the descending colon to your rectum, in an “S”shape
The rectum joins the anus, which is the opening where stool passes out of your body.
You may have a colonoscopy to:
- Look for problems in your colon such as early signs of cancer, red or swollen (inflamed) tissue, open sores (ulcers) or bleeding.
- Examine the inside of your colon to check for polyps, and screen for colorectal cancer; check for the cause of blood in the stool or rectum, chronic diarrhea, iron deficiency anemia, or long-term, unexplained belly or rectal pain.
- Examine the inside of your colon after abnormal test results from a barium enema, blood in stool test, CT colonography scan, stool DNA test or sigmoidoscopy.
- Treat colon problems such as inflammatory bowel disease (IBD).
- Clean the lining of your colon with a water jet (irrigate).
- Remove any liquid stool with a suction device.
- Inject air into your bowel to make it easier to see inside.
- Work inside your bowel with surgical tools.
A colonoscopy is used to screen for colorectal cancer. A screening means looking for cancer in people who don’t have any symptoms of the disease. A colonoscopy can help your provider look for and treat (if needed) problems in your colon such as colon polyps, tumors, ulcers, redness or swelling (inflammation), pouches (diverticula) along the colon wall, narrow areas (strictures) of the colon, and any objects that might be in the colon.
More information on colorectal cancer and other gastrointestinal procedures is found under Colonoscopy and Colorectal Cancer.
What happens during a colonoscopy?
More information is found under “What to Expect on the Day of your Procedure”
You may have your colonoscopy as an outpatient, meaning you go home the same day. Or your colonoscopy may be done as part of a hospital stay. The way your procedure is done varies depending on your condition and your health care provider’s practices. The colonoscopy follows this general process:
- Arrive and check-in approximately 45 minutes prior to your scheduled appointment time.
- You may be asked to remove any jewelry or other objects that might get in the way.
- You will be asked to remove your clothing and be given a gown to wear.
- An IV (intravenous) line with a sedative or pain medicine will be inserted in your arm or hand.
- You may be given oxygen to breathe.
- Your heart rate, blood pressure, respiratory rate and oxygen level will be monitored.
- You’ll be asked to lie on your left side with your knees pulled up towards your chest.
- Depending on the type of anesthesia or sedative, you may be completely asleep. If you’re awake, you may be asked to take slow, deep breaths or change your position while the tube is being inserted. This helps to relax your abdominal muscles and decrease discomfort.
- A colonoscope will be lubricated, put into your anus, and moved into your rectum and colon. You may feel mild pain, pressure or cramping but the sedative should reduce your discomfort.
- Your health care provider will check your colon and may take photos. If a polyp is found, it may be taken out or left there until another procedure is done.
- Once finished, the tube will be taken out and you will be moved to another room to recover.
At what age should I have my first colonoscopy and how often do I need one?
In general, you should have your first colonoscopy when you are 45. If you don’t have any risk factors, it’s screening is recommended every 10 years. If you have risk factors (e.g., personal or familial history of polyps, familial history of colorectal cancer, a personal medical history of cancer), you should be screened more frequently, such as every five or seven years. There are additional factors that may increase your risk of developing a polyp or colorectal cancer. Talk to your doctor about when and how frequently you should have a colonoscopy.
Are there alternative procedures or tests to a colonoscopy that provide the same results?
A colonoscopy is the best way to identify polyps or other risks for colon cancer, but for some patients with fewer risk factors, there are alternatives that your provider may recommend between colonoscopies. One alternative to a colonoscopy is a fecal immunochemical test (FIT). This test looks for hidden blood in the stool that may indicate the presence of polyps or cancer. Speak with your primary care provider (PCP) to see if you are a candidate for FIT testing, and if so, your PCP will order it. Another alternative to a colonoscopy is Cologuard, a colon cancer screening tool done at home. Our providers do not typically recommend or order Cologuard testing.
More about other gastrointestinal procedures can be found under “Other Gastrointestinal and Endoscopic Procedures”
What are the associated risks and complications with a colonoscopy?
All procedures have risks. Some possible risks of a colonoscopy include:
- Continued bleeding after tissue sample (biopsy) or polyp removal
- Nausea, vomiting, bloating, or rectal irritation caused by the procedure or by the bowel cleansing (prep)
- Bad reaction to the pain medicine or the medicine used to relax you (sedative)
- A perforation (small hole) or tear of the colon wall that may cause bleeding, which is rare
Depending on your condition, you may have other risks. Discuss any concerns with your provider before your procedure.
Other Gastrointestinal and Endoscopic Procedures
The following procedures are also used to examine the colon. Many of these procedures may be done before a colonoscopy. Depending on the results, your doctor may recommend a colonoscopy for further examination.
- Sigmoidoscopy
- Upper Gastrointestinal (UGI) Endoscopy
- CT Colonography
- Fecal Immunochemical Test (FIT Test)
- Stool DNA Test (Cologuard)
- Barium Enema
This diagnostic procedure examines the sigmoid colon, the lowest part of your colon closest to the rectum. This test is used to diagnose conditions with symptoms of diarrhea, constipation, belly pain, polyps and bleeding. Similarly to a colonoscopy, during a sigmoidoscopy, a long flexible tube, called a sigmoidoscope, is put into your rectum and moved into your sigmoid colon. The sigmoidoscope has a tiny camera and light on one end that are used to look for colon polyps and signs of ulcerative colitis.
Upper Gastrointestinal (UGI) Endoscopy
This diagnostic procedure examines the upper gastrointestinal tract, which contains the mouth, esophagus, stomach and first part of the small intestine (the duodenum). During a UGI endoscopy, a long flexible tube, called an endoscope, is put into your mouth, and moved into your throat, esophagus, stomach and duodenum. The endoscope looks for ulcers, narrowing or blockages, swelling, celiac disease, or Crohn’s disease. Your provider may insert additional tools to obtain tissue samples for a biopsy, remove stuck items or stop bleeding.
This diagnostic procedure is a virtual colonoscopy in which a CT (computed tomography) scan is used to examine the inside of the colon and rectum. You will likely be asked to follow a prep procedure, similar to the one for a colonoscopy, to clear out your bowels before the procedure. The scan uses low-dose radiation to take pictures of the inside of your colon and rectum to look for polyps and cancer.
Fecal Immunochemical Test (FIT Test)
This test is used to determine if there is blood in your stool, which may indicate polyps on the colon, hemorrhoids (swollen blood vessels), ulcers, Crohn’s disease or diverticulitis. This is an at-home test in which three stool samples will be collected and examined by your provider.
This test looks for abnormal DNA that may be related to colon polyps and/or colon cancer. Similarly to a colonoscopy, this test is done to screen for colon cancer or colon polyps in people with no symptoms. Our providers don’t order Cologuard, but instead order FIT testing when appropriate.
This test looks for abnormal growths on the lower gastrointestinal tract, including the colon and rectum. The colon is filled with barium sulfate that appears white on X-ray films. During this test, an X-ray is taken of the lower gastrointestinal tract to view abnormalities, such as inflammation (swelling), polyps or cancer.
The following procedures are done by our providers to diagnose other gastrointestinal conditions and diseases.
- Video Capsule Endoscopy
This painless and noninvasive approach may be used to examine your gastrointestinal tract. During this procedure, you swallow a disposable, miniature video camera contained in a capsule. It delivers high-quality color images while you continue normal daily activities. This technology can diagnose conditions such as Crohns’ disease, celiac disease, tumors, iron deficiency anemia and obscure bleeding. - Endoscopic Ultrasound
This procedure plays an important role in the management of upper gastrointestinal disorders of the esophagus, pancreas, stomach, lung and bile duct. With this technology, our doctors can view various types of cancers, evaluate chronic pancreatitis, and study abnormalities of the bile duct and lesions in the intestinal wall. - Photodynamic Laser Therapy
This is a nonsurgical treatment of esophageal cancers and Barrett’s esophagus. Through an IV, a photosensitive drug is delivered to your cancer cells. A laser then activates the drug, which then destroys the abnormal cells. - Double Balloon Enteroscopy (DBE)
This procedure is performed with one of the few specialized scopes available in the United States. DBE allows the doctor to view your entire small intestine. More importantly, it allows your doctor to perform various procedures throughout the small intestine.
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