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Irritable Bowel Syndrome Diagnosis (Rome III criteria)

Irritable Bowel Syndrome Diagnosis and Treatment

Recurrent abdominal pain or discomfort (uncomfortable sensation not described as pain) at least 3 days/month in the last 3 months with symptom onset at least 6 months prior to diagnosis?

Is there improvement  with defecation?

Is the onset associated with a change in frequency of stool?

Is the onset associated with a change in form (appearance) of stool?

Updated Diagnostic Criteria - Rome IV

The Rome IV criteria introduced two major changes compared to the previous Rome III criteria. 5,6  The new criteria no longer includes abdominal discomfort as part of the definition of IBS. Abdominal pain is now required  in order to meet the new diagnostic criteria.  Another important change was the change in symptom frequency:

Rome IV: Abdominal pain should be present at least 1 day per week on average during the preceding month.  Rome III:  at least 3 days per month.  The new criteria are not likely to change the incidence of IBS in clinical populations.5 

Access our IBS diagnosis calculator based on the Rome IV criteria

info  The diagnosis of IBS requires not only meeting the diagnostic criteria, but also on a limited number of additional tests based on the symptoms reported.

The Rome IV criteria also redefined the four subtypes of IBS as follows:
  • IBS with constipation (IBS-C):   >25% hard stools and <25% loose stools
  • IBS with diarrhea (IBS-D): >25% loose stools and <25% hard stools
  • IBS with mixed bowel habits (IBS-M):  >25% loose stools and >25% hard stools
  • Unclassified IBS (IBS-U):  <25% loose stools and <25% hard stools.

This new approach is more likely to reflect experience from clinical practice and should substantially reduce the IBS-U group while increasing the IBS-M group.


Rome III Diagnostic Criteria for Functional Gastrointestinal Disorders. Appendix A. Accessed: July 2017. Guidelines.  

 [In pathophysiology research and clinical trials, a pain/discomfort frequency of at least 2 days a week during screening evaluation is recommended for subject eligibility. ]
Rome iii criteria for IBS