There is no single test to definitively diagnose IBS.
However, symptom-based diagnosis of IBS can be made with a high degree of confidence using the Rome IV criteria. These criteria include abdominal pain lasting on average at least one day a week over the last three months and associated with at least two of the following factors:
- Pain and discomfort are related to having a bowel movement
- Altered frequency of passing stool
- Change in consistency of stool
Other symptoms that may be associated with IBS include the passage of mucus, straining to pass stool, urgency or a feeling of incomplete evacuation.