How are IBS subtypes distinguished?
IBS subtypes are differentiated based on stool form and not stool frequency.
Using the Rome III definition, subtypes are differentiated based on the percent of bowel movements with hard or lumpy stools versus those with loose or watery stools. It should be noted that patients frequently switch between subtypes.
Approximately one third of patients with IBS have IBS with diarrhea (IBS-D), one third have IBS with constipation (IBS-C), and the remainder have IBS with mixed constipation and diarrhea (IBS-M)