Differential Diagnosis

The Rome IV criteria aids in the diagnosis of irritable bowel syndrome (IBS), as well as in the classification of IBS. Colonoscopy is indicated when alarm symptoms/signs, risk factors, and/or abnormal physical exam findings are present. In this chapter, we describe various conditions that should be considered in the differential diagnosis of IBS, including bile acid diarrhea, celiac disease, food, chronic gastrointestinal infection, inflammatory bowel disease, microscopic colitis, colorectal cancer, drug-induced diarrhea or constipation, amyloidosis, and small intestinal bacterial overgrowth. When Rome IV features for IBS are negative, other functional gastrointestinal disorders, including functional abdominal pain, functional bloating, functional constipation, functional diarrhea, or unspecified functional bowel disorder, should be considered.