Irritable Bowel Syndrome

Diagnosis

Mayo offers the latest in screening and diagnostic services for IBS. Physicians work together to rule out diseases such as inflammatory bowel disease, celiac disease or microscopic colitis that can be misdiagnosed as IBS. The diagnosis of IBS is determined through various tests:

• A complete medical history and physical exam
• Stool studies
• Flexible sigmoidoscopy, which examines the lining of the lower third of the large intestine (the sigmoid colon) with a flexible, lighted tube or scope
• Colonoscopy, which examines the entire length of the colon with a small, flexible tube to help rule out conditions such as ulcerative colitis, Crohn's disease or colorectal cancer
• Tests to rule out lactose intolerance, an inability to tolerate sugar (lactose) in dairy products or sorbitol
• In patients whose primary symptom is constipation, a number of tests can help clarify the source of the problem

Rome Criteria

Researchers have developed the Rome Criteria to assist in the diagnosis of IBS. The most important are abdominal pain and diarrhea or constipation lasting at least three months in one year. Under this criteria, IBS patients also have at least two of the following symptoms one-fourth or more of the time:

• A change in the frequency or consistency of the stool; for example, from having one normal stool every day to several loose stools per day — or to only one hard stool every three to four days
• Straining, urgency or a feeling that bowels cannot be emptied completely
• Mucus in the stool
• Bloating or abdominal distention
• Abdominal pain/cramps relieved by bowel movements