The Rome IV criteria can be used to diagnose IBS based on the proportion of bowel movements rated as constipation or diarrhea compared to those rated as normal. Symptoms need to occur at least once per week for at least three months to be considered IBS.[1] However, there is no exact test for IBS, so a doctor (often a gastroenterologist) may need to rule out other potential diseases with blood and stool tests, and they might also perform a colonoscopy.[2]
How is IBS diagnosed?
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•Last Updated: May 16, 2025
Irritable bowel syndrome (IBS) is diagnosed using the Rome IV criteria, which requires symptoms to occur at least once per week for 3 months, with bowel movements categorized as constipation or diarrhea. Because there is no definitive test for IBS, doctors may conduct blood and stool tests and possibly a colonoscopy to rule out other conditions.