Duration and severity of congenital hydronephrosis as a cause of smooth muscle deterioration in pyelo-ureteral junction obstruction.

A potential relationship between duration and severity of obstructive hydronephrosis and the histological structure of the upper urinary tract smooth musculature has been studied in a series of prenatally diagnosed cases. Between 1981 and 1988, fifty-five monolateral pyelo-ureteral junction obstructions (PUJO), prenatally diagnosed (16th-37th week of gestational age), underwent pyeloplasty between 4 and 90 days of life. Gestational age at the diagnosis, delta t (duration of hydronephrosis from first detection in utero to surgery) and V (volume of the hydronephrotic kidney) were related to the frequency of muscle hypotrophy and fibrosis of both pelvis and ureter just above and below the junction. A close correlation between duration (delta t) and the severity of the involvement of the smooth musculature of the upper urinary tract was found. The larger the volumes (V), the more severe the muscular damage. In the long-term follow-up, poor results were obtained only in 5 of the 19 newborn who had severe hypotrophy and fibrosis of the pelvis. In conclusion, in PUJO, the shorter the delta t and the lower the V, the better one expects the smooth musculature of the upper urinary tract to be.