Electrophysiological investigation of hydronephrosis in children.

The hydrostatics and dynamics of the upper urinary tract were studied in 12 children with congenital hydronephrosis by means of intrapelvic pressure and bipolar electromyography leads from the pelvis and ureter. Studies were performed intraoperatively with the child under general anesthesia. Measurements were obtained during a baseline period of normal diuresis and during diuresis induced by furosemide. The baseline pressure in the hydronephrotic pelvis was within normal limits in most cases but a tendency toward an increased mean baseline pressure was observed in severe hydronephrosis when the cases were grouped according to the excretory urogram. During diuresis the average pressure increase in severe hydronephrosis was parallel to that in moderate hydronephrosis. The peristaltic pattern showed discoordination in pelvis conus transmission but usually preserved anterograde transmission from the conus down the ureter. The results seem to indicate a slight functional obstruction at the pelvioureteral junction. This obstruction leads to the observed alterations in peristalsis and to a slight elevation of the intrapelvic pressure in more severe cases.