Rome IV IBS Subtype Screener
The Rome IV consensus defines Irritable Bowel Syndrome (IBS) as recurrent abdominal pain occurring at least 1 day per week over the previous 3 months, with symptom onset at least 6 months prior. The pain must be associated with at least two of the following features: related to defecation, associated with a change in stool frequency, or associated with a change in stool form.
IBS is categorized into four clinical subtypes based on the Bristol Stool Scale proportions observed on symptomatic days: IBS-C (constipation-predominant), IBS-D (diarrhea-predominant), IBS-M (mixed bowel habits), and IBS-U (unclassified). Complete the 4-step questionnaire below to determine which category your symptom pattern matches.
Abdominal Pain Frequency & Duration
Understanding the four Rome IV IBS subtypes
Subtyping is not determined by how you feel on normal days, but specifically by the consistency of stool passed during days with abdominal pain or altered bowel movements:
Constipation predominant
More than 25% of bowel movements are Bristol Types 1 or 2 (pellets, hard sausage), and fewer than 25% are Bristol Types 6 or 7. Often linked to delayed colonic transit.
Diarrhea predominant
More than 25% of bowel movements are Bristol Types 6 or 7 (mushy, liquid), and fewer than 25% are Bristol Types 1 or 2. Associated with rapid transit and visceral hypersensitivity.
Mixed bowel habits
More than 25% of bowel movements are hard (Bristol 1-2) AND more than 25% are loose (Bristol 6-7). Bowel habits fluctuate unpredictably from week to week.
Unclassified
Diagnostic pain criteria are met, but fewer than 25% of movements are hard and fewer than 25% are loose. Stool forms remain mostly intermediate (Bristol 3-5).
Why longitudinal logging is mandatory
Clinical gastroenterologists do not make definitive IBS management plans based on retrospective memory alone. Studies show patients consistently overestimate diarrhea episodes and underestimate normal bowel movements. Rome IV consensus guidelines recommend prospective daily symptom logging for at least 8 to 12 weeks to establish an accurate Bristol percentage baseline and identify food triggers.