Is "indeterminate colitis" Crohn's disease in the long-term follow-up?

The diagnosis of "indeterminate colitis" was found in 6 patients of 147 operated patients (4%) as compared to the indeterminate diagnosis in 59 of 465 non-operated colitis patients (13%) at the register of inflammatory bowel diseases of Tampere University Hospital. The long-term natural course of the six surgically treated "indeterminate colitis" patients was analysed. The term "indeterminate colitis" included macroscopically either Crohn's colitis or ulcerative colitis which histologically remained indeterminate both pre and peroperatively. Clinicopathological follow-up after the median 5 1/2 years indicated typical Crohn's disease in one case and probable in two cases. However, the final diagnosis remained indeterminate in three cases. The results of the present study showed that patients with indeterminate colitis may have a tendency for Crohn's colitis in the long-term follow-up and thus should be considered when planning an ileal pouch-anal anastomosis.