In this Article

• What is irritable bowel syndrome (IBS)?
• What causes IBS?
• What are IBS symptoms?
• What are the complications of IBS?
• How is IBS diagnosed?
• How is IBS treated?
• Is there a relationship between IBS and small intestinal bacterial overgrowth?
• What is a reasonable approach to IBS?
• What is in the future for IBS?
• IBS At A Glance
• Patient Discussions: Irritable Bowel Syndrome - How Was Diagnosis Established
• Irritable Bowel Syndrome Glossary
• Irritable Bowel Syndrome Index

IBS At A Glance

• IBS is a functional disease, that is, a disease in which the intestine (bowel) functions abnormally.
  
  
• Theories of the cause of IBS include abnormal input from intestinal sensory nerves, abnormal processing of input from the sensory nerves, and abnormal stimulation of the intestines by the motor nerves.
  
  
• The primary symptoms of IBS are constipation, diarrhea, and abdominal pain. Secondary symptoms include abnormal passage of stool, abnormal form of stool, increased amounts of mucus in the stool, and a subjective feeling of abdominal distention (bloating).
  
  
• IBS is diagnosed on the basis of typical symptoms (Rome Criteria) and the absence of other intestinal and non-intestinal diseases that might give rise to the symptoms. Testing in IBS is directed primarily at excluding the presence of other intestinal diseases and non-intestinal diseases.
  
  
• Treatment of IBS consists primarily of medications to control constipation, diarrhea, and abdominal pain. Anti-depressant medication and psychological treatments also may be used. It is not clear if dietary alterations have much effect on the symptoms of IBS except for increases in dietary fiber, which may improve constipation.
  
  
• Although it has been hypothesized that IBS may be caused by intestinal bacteria, specifically by small intestinal bacterial overgrowth, there is little rigorous scientific support for the hypothesis.
  
  
• Future advances in the treatment of IBS depend on a clearer understanding of its cause(s).

Previous contributing editors: Leslie J. Schoenfield, MD, PhD and Dennis Lee, MD

Irritable Bowel Syndrome - How Was Diagnosis Established

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