[Spontaneous fistulae and abscesses of the upper urinary tract (author's transl)]

Spontaneous cutaneous fistulae and abscesses of the renal pelvis and ureter have become rare. Six case reports demonstrate their etiology and differential diagnostic problems. If there is no underlying urologic disease, above all no urolithiasis, other causes of fistulae and abscesses should be kept in mind, the most frequent of these being Crohn's disease.