- Patients who could not be properly diagnosed according to the classical morphological criteria and had overlapping features of both diagnoses CD and UC
- In the original description the specimen shows transmural inflammation and deep ulcers and fissures extending into the muscularis propria, but they did not show granulomata and the lymphoid hyperplasia associated with Crohn’s disease.
- In the era of colonoscopy
- Biopsies alone are not sufficient for a diagnosis of indeterminate colitis
- The term IBD unclassified has been agreed on for use in patients not yet operated on and for whom a definite diagnosis cannot be establishes
- The main issue is consideration of restorative procedure in indeterminate colitis given the risk of Crohn’s disease with the potential for significant small bowel loss and perianal fistula disease
- Case series suggest that if features do not suggest Crohns a pouch is a reasonable option
- Given IBD unclassified does not necessarily mean the final histology will show indeterminate colitis most experts recommend a staged procedure to confirm the diagnosis prior to considering a restorative procedure