Diagnosing Irritable Bowel Syndrome (IBS)

It's normal to have diarrhea or constipation from time to time. But if these problems happen often and occur with symptoms such as stomach pain or discomfort, you should see a doctor about the possibility of having irritable bowel syndrome (or IBS).

A doctor who suspects IBS may ask about your symptoms, review your medical history, take a physical exam, and perform diagnostic testing.

No matter how embarrassing, it is important to talk with your doctor openly and honestly about your symptoms. You'll need to tell your doctor about stomachaches, bloating, and any change in the appearance and frequency of your bowel movements.

Ruling Out Other Illnesses

Since there appear to be no physical changes associated with IBS, doctors have traditionally made the diagnosis by ruling out other possibilities.

Mention if you've had nausea, vomiting, fever, persistent pain, blood in the stool, or weight loss. These particular symptoms are NOT signs of IBS and may indicate other serious illnesses.

During the medical history review and physical checkup, your doctor will likely try to rule out the presence of other illnesses such as inflammatory bowel disease (IBD), colon cancer, or celiac disease.

Diarrhea, abdominal bloating, and constipation can be particularly misleading symptoms, since they are signs of various ailments. Plus, the physical exam may point to other disorders. For instance, weight loss, ulcers, and arthritis may identify inflammatory bowel disease instead of IBS.

To further exclude other illnesses, doctors may order blood and stool tests. They may ask for a breath test or ask you to temporarily eliminate dairy products from your diet to determine whether you're lactose intolerant.

They may also conduct a flexible sigmoidoscopy, in which a flexible, finger-sized tube with a camera is placed inside the rectum to examine the lower part of the colon.

The entire colon and the rectum may also be analyzed with a colonoscopy, a long flexible, finger-sized tube with a camera placed inside the rectum.

IBS Diagnostic Criteria

Not all doctors agree that the best way to diagnose IBS is through the exclusion of other diseases. Some researchers suggest a more "positive approach" using guidelines called the Rome II criteria.

According to the criteria, certain symptoms must be present before IBS can be diagnosed. The patient must have experienced at least 12 weeks or more of stomach pain and distress in the past year. The pain and distress must be associated with at least two of these three features:

• A bowel movement relieves the ache and suffering.
• There's a change in how often the stool comes out.
• The stool looks different.

Certain symptoms must also distinguish IBS, such as:

• A change in frequency of bowel movements
• A change in the appearance of body waste
• Bowel movements feel uncontrollably urgent, difficult to pass, or incomplete
• Mucus comes out with the stool
• Bloating or abdominal distension

If you are concerned, see your doctor regardless of whether you meet the Rome II criteria. Some doctors say Rome II criteria are too rigid and may miss borderline patients. For instance, some patients may not remember exactly how long their symptoms persist, says Philip Schoenfeld, MD, MSEd, MSc. He is co-author of the American Academy of Gastroenterology's treatment guidelines.

Before or after a visit with your doctor, it may also help to keep a symptom journal. This record of problems and potential triggers could help you and your physician determine what you have, how to avoid trouble, and how to best treat it.