Table 1.

Summary of diagnostic criteria used to define irritable bowel syndrome

Diagnostic criteria	Symptoms, signs, and laboratory investigations included in criteria
Manning (1978)	IBS is defined as the symptoms given below with no duration of symptoms described. The number of symptoms that need to be present to diagnose IBS is not reported in the paper, but a threshold of three positive is the most commonly used:
	Abdominal pain relieved by defecation
	More frequent stools with onset of pain
	Looser stools with onset of pain
	Mucus per rectum
	Feeling of incomplete emptying
	Patient-reported visible abdominal distension
Kruis (1984)	IBS is defined by a logistic regression model that describes the probability of IBS. Symptoms need to be present for more than two years.
	Symptoms:
	Abdominal pain, flatulence, or bowel irregularity
	Description of character and severity of abdominal pain
	Alternating constipation and diarrhea
	Signs that exclude IBS (each determined by the physician):
	Abnormal physical findings and/or history pathognomonic for any diagnosis other than IBS
	Erythrocyte sedimentation rate > 20 mm/2 h
	Leukocytosis > 10000/cc
	Anemia (Hemoglobin < 12 for women or < 14 for men)
	Impression by the physician that the patient has rectal bleeding
Rome I (1990)	Abdominal pain or discomfort relieved with defecation, or associated with a change in stool frequency or consistency,
	PLUS two or more of the following on at least 25% of occasions or days for 3 mo:
	Altered stool frequency
	Altered stool form
	Altered stool passage
	Passage of mucus
	Bloating or distension
Rome II (1999)	Abdominal discomfort or pain that has two of three features for 12 wk (need not be consecutive) in the last one year:
	Relieved with defecation
	Onset associated with a change in frequency of stool
	Onset associated with a change in form of stool
Rome III (2006)	Recurrent abdominal pain or discomfort three days per month in the last 3 mo associated with two or more of:
	Improvement with defecation
	Onset associated with a change in frequency of stool
	Onset associated with a change in form of stool

IBS: Irritable bowel syndrome; 5-HT: 5-hydroxytryptamine.