[Fold formations in the proximal ureter].

Over a period of thirteen years in 28 children (age 4 weeks to 11 years) mucosal membranes of the proximal ureter were diagnosed by intravenous urography. In 61% of all cases the anomalies were demonstrated within the first year of life. Predominantly boys were affected (75%). Most of the associated anomalies (n = 15) were related to the urogenital system (n = 7). The membranes were bilateral in 12 cases and either separate (n = 15) or multiple (n = 25), resulting in a cork-screw-like structure. Minor signs of obstruction of the corresponding renal pelvis were found in 45%, independent of the number of membranes. Urinary tract infection (UTI) occurred in half of all cases. Kidney length was not reduced in any child. The mean serum creatinin (SCR) level was 0.6 +/- 0.4 mg/dl. Surgical correction was never performed. The clinical follow-up investigation (n = 14) after a mean period of 5.1 (1-14) years revealed recurrent UTI in only 2 patients. The mean SCR level remained normal (0.5 +/- 0.3 mg/dl). The tendency of involution of the membranes, supposed by the clinically benign course, is demonstrated to serve as an example. Although a predisposing effect to UTI cannot be excluded, ureteral membranes must be regarded as harmless and transitory anomalies of the growing ureter in childhood which do not require urologic intervention.