Please note: This information was current at the time of publication but now may be out of date. This handout provides a general overview and may not apply to everyone. 

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Am Fam Physician. 2001;63(7):1383-1384

What is flexible sigmoidoscopy?

Flexible sigmoidoscopy is a way to look at the colon (the large bowel) using a flexible, lighted tube to see the inside of the bowel for any abnormal growths or inflammation of the colon wall. The anal canal also is examined with a short tube as part of this exam for colon diseases.

What are the benefits of flexible sigmoidoscopy?

Flexible sigmoidoscopy is an effective tool to prevent and detect early colon cancer. Colon cancer is the second most common cause of death from cancer in the United States. Many lives can be saved if precancerous growths (called polyps) are discovered before they become cancerous, or if colon cancer is discovered before it has spread. Sigmoidoscopy also can diagnose inflammation of the colon from conditions such as ulcerative colitis or Crohn's disease. Other colon conditions such as diverticulosis also can be diagnosed.

Who should have the procedure?

People who have problems such as persistent abdominal pain, rectal bleeding, persistent diarrhea or anemia (low blood counts) may need flexible sigmoidoscopy. Everyone (even those without these complaints) older than 50 years should undergo the exam every 3 to 5 years to screen for colon diseases.

How do I prepare for the procedure?

Eat a clear liquid diet the afternoon and evening of the day before the scheduled sigmoidoscopy. Take two Fleet enemas at home just before the exam. Your doctor will tell you how to prepare.

Is the exam uncomfortable?

The exam produces some discomfort and abdominal pressure. Air is placed in the colon to allow for viewing, and the air can produce cramping. Most people tolerate the exam well and prefer not to be sedated so that they can resume normal activities immediately afterward. People who are sedated have a slightly increased risk of colon perforation (a hole created in the wall of the colon). The short exam time (usually 5 to 20 minutes) helps make this a tolerable procedure.

Are biopsies performed during sigmoidoscopy?

Most procedures do not require biopsies, but occasionally a biopsy of a growth is needed. The biopsy specimen is obtained by clipping a small piece of tissue inside the colon and removing it through the viewing tube. If a biopsy is performed, you may have some minimal discomfort or slight bleeding from the rectum for several days.

Preparing for Flexible Sigmoidoscopy

  1. you may have a clear liquid diet the afternoon and evening before the exam. This includes broth, juices, clear beverages and clear soups.

  2. Avoid taking aspirin, iron pills or the blood-thinning medicine called Coumadin for one week before the procedure.

  3. Purchase two Fleet enemas at any pharmacy. These should be used the day of the exam. The first enema is given 2 hours before the scheduled exam. The second enema is given 1 hour before the scheduled exam. Try to hold each enema for several minutes and then evacuate the bowel completely.

  4. Arrive at the office at least 20 minutes before the scheduled exam. Let the nurse know if you do not think your bowel was completely emptied, or if the second enema still produced a large amount of solid stool.

  5. If you are diabetic and take insulin, take your usual insulin dose the morning of the procedure. Make up your calories with clear liquids as you would on a sick-day diet. You can check your blood sugar frequently and carry juice with you if you should develop hypoglycemia.

Following Flexible Sigmoidoscopy

  1. You may feel full of air and feel discomfort following the procedure. You will be offered the opportunity to go to the bathroom immediately after the procedure or once you have dressed.

  2. Your doctor will return and discuss the findings of the exam. Feel free to ask any questions you may have.

  3. You should be able to drive yourself home following the procedure unless you required additional sedative medicines (oral sedatives or intravenous medicines) for completion of the procedure.

  4. You will probably continue to note air and cramping once you leave the office. Walking can help to eliminate excess air left in your colon following the procedure.

  5. You can help relieve any discomfort after the procedure by taking ibuprofen (brand names: Advil, Motrin, Nuprin), three 200-mg tablets three times a day with food, or you can take acetaminophen (brand name: Tylenol), two 325-mg tablets every 4 hours.

  6. The rare, but more severe, complications of sigmoidoscopy usually produce severe abdominal pain, vomiting and an enlarging abdomen. If any of these symptoms occur, or if you don't feel well following the procedure, please call your doctor's office right away.

  7. Minimal bleeding into your stool can be noted after flexible sigmoidoscopy. If the scope slides past a hemorrhoid or if biopsies are performed, bleeding is more likely. If you have excessive bleeding or large blood clots in your stool, contact your doctor's office right away.

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