Inflammatory bowel disease (IBD), although occasionally used to encompass a variety of infective and purely inflammatory bowel conditions, usually refers to two idiopathic conditions:
Indeterminate colitis is added to the list and represents approximately 6% of inflammatory bowel disease cases . It has features both on imaging and histologically which overlap both Crohn disease and ulcerative colitis.
Strictly speaking, microscopic colitis (with its two subtypes lymphocytic and collagenous) also belongs to the list. Characterized by chronic diarrhea with normal radiologic and endoscopic findings and typical findings on histologic examination of colonic tissue and as such a medical differential diagnosis, they will not be covered here.
For specifics regarding above listed dominating entities please refer to their separate articles. Other than sharing a common lack of understanding as to their underlying etiologies, they are separate entities with little overlap.
Recognized classifications include:
- Montreal classification of inflammatory bowel disease
- Vienna classification of inflammatory bowel disease