[Prerequisites for therapy of inflammatory bowel diseases. Pathophysiology--symptomatology--diagnosis]

The etiology of the idiopathic chronic inflammatory bowel diseases Crohn's disease and ulcerative colitis remains unclear. Differences in prognosis, medical and surgical treatment, and the nature of expected complications require not only a differential diagnosis vis-a-vis other disorders, but also the correct diagnosis of these two diseases. Symptomatology and clinical presentation can be mimicked both by infectious, ischemic and other chronic bowel diseases such as collagenous colitis, eosinophilic colitis, and Behçet's disease. This means that, in the absence of pathognomonic changes, the correct diagnosis can be established only on the basis of all the findings (laboratory, endoscopy, X-rays), and sometimes only on the basis of the course of the condition. The most important differential diagnostic procedure has proved to be ileocolonoscopy, since in addition to gross evaluation of the mucosa, targeted removal of biopsy specimens is also possible.