[Prestenotic narrowing in the upper urinary tract (author's tract)].

While prestenotic dilatation in the upper urinary tract is considered as a characteristic radiological feature, earlier narrowing due to compensating hypertrophy of the musculature is either ignored or misinterpreted. Several examples of prestenotic narrowing are demonstrated and their significance in radiological diagnosis is stressed. This raises the question whether the narrowing of the ureters, seen in cases of bladder neck obstruction, particularly with prostatic hypertrophy, can be explained by a similar physiopathological response. This question can only be answered by performing pressure measurements during the course of radiological examination; the results would, however, be of doubtful value since the introduction of the ureteric catheter would lead to an additional unphysiological state.