IBS Fact : Evidence-based management of irritable bowel syndrome

Flexible sigmoidoscopy in irritable bowel syndrome (IBS)

Flexible sigmoidoscopy is a visual inspection of the rectum and the lower part of the colon (also known as the sigmoid colon, hence sigmoidoscopy). This is performed using an endoscope, which consists of a thin flexible tube with a camera and a light source mounted on its top. Using the endoscope, the doctor can inspect the lining of the colon for inflammation, ulcers, abnormal growth such as tumours and polyps, and bleeding. It also allows collection of small tissue samples (biopsies) from any suspicious area. These can be further analysed by microscopy to determine more precisely the type of inflammation or to exclude any possible malignancy. Polyps (cherry-like protuberances), which are usually harmless, can also be removed if found. Since IBS is not accompanied by any visible changes of the intestinal wall, sigmoidoscopy is primarily performed to exclude other diseases, particularly in patients with certain red flags such as abdominal pain, rectal bleeding, constipation, unexplained weight loss, or black, tarry stools. Patients above 50 and those with a familial history of intestinal cancers may also be recommended to undergo a sigmoidoscopy to check for colon and rectal cancer. Sigmoidoscopy may be indicated in persons with a familial history of IBD, such as Crohns disease and ulcerative colitis.

What is the preparation for flexible sigmoidoscopy?

To enable visibility, the colon has to be cleaned out prior to the procedure. This is usually done by enema right before the examination. You may also be required to drink only clear liquids for 12 to 24 hours beforehand and refrain from ingesting any food eight hours before the procedure. Although laxatives are usually not required, they may be prescribed in some hospitals or clinics. These are usually taken the night before the procedure and require frequent bathroom visits, which is considered by many patients more cumbersome than the actual procedure. You may also be requested to refrain from taking certain medications prior to the exam. Sedation is usually not required for this test, but it may be an option to discuss with your doctor ahead of time. If you choose to have a sedative, you will need to make sure that someone accompanies you home. You should also not drive a car for the rest of the day.

What will I experience during flexible sigmoidoscopy?

Sigmoidoscopy is usually performed at the hospital or clinic in a dedicated room. Your doctor will have you lie on your left side, with your knees drawn up. He will insert the sigmoidoscope through the rectum and pass it into your sigmoid colon. The doctor will use a small amount of air to expand the colon for better visibility. You will be encouraged to pass wind to prevent cramping. The doctor will carefully retract the sigmoidoscope while examining the lining of your bowel on a display. You may feel mild cramping during the procedure. The exam takes 10 to 20 minutes. The collection of tissue samples or removal of polyps may be experienced as slightly painful.

What can I expect after a sigmoidoscopy?

Once you have had your test, you will be monitored in a recovery area until well enough to get up. Usually you can resume regular activities right away after the procedure. If you have had sedation, you may feel sleepy for up to 24 hours. Ask your doctor if you’ll need to miss work for a sigmoidoscopy. You will also be given information about follow-up care and what to do if you have a problem. After a sigmoidoscopy, you can expect some abdominal cramping or bloating during the first hour after the procedure. Mild anal bleeding is common and normal, particularly if polyps were removed. Although complications are rare, you should call you doctor immediately if you experience severe abdominal pain, fever or heavy rectal bleeding.

How are the results of a sigmoidoscopy interpreted?

Results of a sigmoidoscopy are generally available right after the procedure. Biopsy results may take a few days. For the majority of patients with suspected IBS, sigmoidoscopy will yield normal (negative) results, i.e. normal appearance of the intestinal mucosa. This further strengthens the diagnosis of IBS and excludes the majority of conditions with similar symptoms with high accuracy. In case of abnormal findings, further examinations, such as colonoscopy (see below) may be indicated.

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