What can be done to diagnose ibs (irritable bowel syndrome)?

Rome criteria: Endoscopy is important to rule out a different reason for your problems, but not necessary to diagnose irritable bowel syndrome. The duration of symptoms , the pattern of pain and the association of discomfort with bowel movements can be used to see if they are compaible with a predefined rome iii criteria which can make a diagnosis of irritable bowel syndrome.