When other diseases of the GI tract have been ruled out, clinicians will rely on Rome criteria to help us diagnosis functional disorders like IBS.
For IBS, Rome Criteria require that patients have had recurrent abdominal pain, on average, at least 1 day per week during the past 3 months associated with 2 or more of the following:
The pain is related to defecation and may be increased or unchanged by defecation
The pain is associated with a change in stool frequency, and/or
The pain is associated with a change in stool form or appearance.
Subtypes of IBS are based on how frequently a patient experiences very loose or very hard stools.
If a patient experiences very loose stools greater than 25% of the time and very hard stools less than 25% of the time, this classifies as IBS-D.
If a patient experiences very hard stools greater than 25% of the time and very loose stools less than 25% of the time, this classifies as IBS-C.