The uncertain primary diagnosis of inflammatory bowel diseases.

BACKGROUND: The purpose of this study is to re-evaluate our series of patients affected by a colonic non-neoplastic disease, in order to measure the percentage in whom we were unable to make a correct diagnosis after the first clinical and histological approach and to single-out the reasons for our inability to reach the correct diagnosis.

METHODS: During the period 1985-1999 we observed 1228 patients affected by chronic inflammatory colonic diseases.

RESULTS: In 859 patients (69.9%) an ulcerative colitis was diagnosed for the first time, and 248 patients (20.1%) were affected by Crohn's colitis. One hundred and twenty-one patients (9.8%) were defined as being affected by an undetermined colitis. Forty-three patients of these had a definite diagnosis, afterwards: 27 patients were affected by ulcerative colitis and 16 by Crohn's colitis. Differential diagnosis between inflammatory large bowel diseases (ILBD) and other forms of colitis was set out as follows: 62 cases out of 1228 were consequent on a bacterial infection or parasitosis; in 28 patients a colitis pseudomembranosus was diagnosed. Eighteen cases of ischemic colitis are reported and 14 patients were affected by NSAID-related colitis. In another 6 patients we diagnosed a postradiation colitis. In 22 cases mimicking a Crohn's colitis we ascertained 9 patients affected by intestinal lymphoma, 11 mycobacterium tuberculosis related intestinal infections and 2 cytomegalovirus related colitis.

CONCLUSIONS: Despite progress in scientific acquisitions and in diagnostic methods, correct initial diagnosis of ILBD is still difficult, even though it will be defined with time.