[Morphological examinations of congenital obstructions of the uretero-pelvic junction in children (author's transl)].

Congenital obstructions of the uretero-pelvic junction of the urinary tract have severe sequelae: urine retention, hydronephrosis, and infections, leading to renal insufficiency without adequate therapy. As the operative results are not always optimal, we studied the morphology of 56 operative specimens and analyzed the structural changes. We found the following conditions causing stenosis of the proximal ureter: 47 localized hypoplasia of the proximal segments of the ureter, systematic hypoplasia in 4 cases, and hypertrophy of the total upper urinary tract in 5 cases. The intrapelvic increase of pressure and the necessary additional work cause characteristic changes of the renal pelvis in the form of hypertrophy of the muscularis and the tunica propria, fibrous destruction of the wall, and secondary formation of valves, which eventually enhance the stenotic effect of the proximal ureter. In the kidneys caliectasis, reduction and hypoplasia of the renal medulla with minor reduction of the renal cortex may be observed. Finally, infections complicate the clinical course. The choice of the surgical procedure should be determined by type and progression of the structural changes and not by personal opinions.