People with irritable bowel syndrome (IBS) experience recurrent bouts of abdominal pain, cramping, bloating, gas, diarrhea and/or constipation in the absence of identifiable metabolic, anatomic or infectious disease. In most cases, a primary care physician or gastroenterologist will diagnose IBS on the basis of patient history and physical findings. Some people require additional tests, such as a colonoscopy, in order to exclude more serious conditions, such as cancer or malabsorptive diseases, as the cause of their symptoms.
Indications for Colonoscopy
According to the American College of Gastroenterology, unintentional weight loss, unexplained or recurrent fevers, anemia, bleeding from the rectum, and/or chronic severe diarrhea constitute "alarm signals," which suggest conditions other that IBS. African American patients over 45 years of age and all other patients over 50 years of age also require colonoscopy in order to rule out cancer.
Preparation
Patients preparing for a colonoscopy for IBS should discuss any medications they are taking, including vitamins and dietary supplements, with their gastroenterologist before scheduling the procedure. Many patients with IBS manage their symptoms with aspirin or aspirin derivatives called "salicylates;" these must be discontinued up to two weeks before a colonoscopy due the risk of bleeding.
Clear Liquid Diet
Bowel preparation for a colonoscopy begins with a clear liquid diet consisting of foods such as fruit juice without pulp, broth, gelatin and sports drinks for one to three days before the procedure. Patients with constipation-predominant IBS should expect to start sooner. All patients must avoid foods with red, orange or purple dyes because these can stain the colon and create a false impression of inflammation.
Laxative
In addition to the clear liquid diet, a gastroenterologist or surgeon will usually prescribe a laxative cocktail to be taken 24 hours before the procedure, in order to clear the colon of any residual stool. Patients who regularly use laxatives may need to take up to twice the normal dosage.
Procedure
In order to perform a colonoscopy, a gastroenterologist or surgeon inserts a flexible tube into the colon via the rectum. The end of the tube supports a tiny camera which provides real time video images. Additional attachments enable the gastroenterologist to obtain specimens for biopsy, remove polyps and cauterize bleeding if it occurs.
Findings
A gastroenterologist or surgeon shares any findings and discusses the plan for follow-up at the end of the procedure. Uncomplicated IBS produces no physical findings and the patient usually follows up with the gastroenterologist for information on lifestyle change and, in some cases, medication.
References
- Irritable Bowel Syndrome (Chapter); C. Owyang; "Harrison's Principles of Internal Medicine, 17th edition;" A.S. Fauci et al. (Eds.); 2008
- National Institutes of Health: How to Prepare for a Colonoscopy
- American Society of Colon and Rectal Surgeons: Colonoscopy
- American Academy of Gastroenterology: Understanding Irritable Bowel Syndrome
