Constant perfusion provocation in idiopathic hydronephrosis.
Twenty-two hydronephrotic units in 20 patients underwent preoperative pressure flow study in combination with electromyographic study of pelvic and ureteric peristalsis. Ten units had a continuous pressure rise during perfusion, whereas the rest had a stabilization of the intrapelvic pressure below 20 cm. of water. The high pressure group was identical with the low pressure group concerning degree of hydronephrosis judged by intravenous urography and function judged by the two-minute uptake of isotope on the renogram. The major difference was the presence of aberrant vessels which were present in 7 of 10 high pressure units and absent in 8 of 12 low pressure units. Long-term records prior to surgery were obtainable in only 1 patient who had spontaneous progression of hydronephrosis during a ten-year period. This unit had a low pressure response to perfusion. The investigation seems to indicate that pressure flow studies might reveal external obstruction, an obstruction which might not be fundamental to the course of the disease. More studies are needed before consequence are to be taken from urodynamic studies of the upper urinary tract.