There is no test to diagnose IBS-C, so doctors often use blood and stool tests to rule out other diseases before reaching an IBS-C diagnosis. Rome IV criteria can be used to diagnose IBS-C based on the proportion of bowel movements rated as constipation compared to those rated as normal.[1] Symptoms need to occur at least once per week for at least three months to be considered IBS.[2]
How is IBS-C diagnosed?
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•Last Updated: May 16, 2025
IBS-C (constipation-predominant IBS) is diagnosed by ruling out other diseases through blood and stool tests because there is no specific test for IBS-C. The Rome IV criteria are used to assess the proportion of bowel movements that are classified as constipation, and symptoms need to occur at least once per week for 3 months to confirm the diagnosis.