Symptom-Based Positive Diagnosis of Irritable Bowel Syndrome

There has been a move in the last 30 years or so towards symptom-based positive diagnosis of irritable bowel. This means that if patients have the classical symptoms of colicabdominant pain, the pain is released by having a bowel movement. But as you said, you can't be absolutely sure about the diagnosis based only on symptoms. And so some screening tests checking the hemoglobin, maybe checking for inflammation like with a serum-cereactive protein are generally recommended.