What is a key criterion used to diagnose irritable bowel syndrome (IBS)?

A key criterion used to diagnose irritable bowel syndrome (IBS) is that abdominal pain or discomfort is often relieved with defecation. This symptom is central to the Rome criteria for diagnosing IBS, which include various patterns of abdominal pain along with altered bowel habits. The relief of pain following a bowel movement is significant because it differentiates IBS from other gastrointestinal disorders that may present with abdominal pain but do not improve with defecation.

Chronic constipation is a symptom that can be associated with IBS, but it is not specific to the diagnosis, as it might be present in various other conditions. Persistent vomiting and severe weight loss are more indicative of other underlying gastrointestinal disorders, such as infections, malignancies, or severe metabolic issues, rather than IBS specifically. Thus, the symptom of pain relieved by defecation stands out as a key criterion in the clinical assessment for diagnosing IBS.