Mechanism of upper tract dilatation in patients with thick walled bladders, chronic retention of urine and associated hydroureteronephrosis.

The mechanism of upper tract dilatation in patients with obstructive uropathy associated with thick walled trabeculated bladders and painless retention of urine has been determined in 9 cases by simultaneous measurement of renal pelvic and bladder pressures under baseline conditions and after administration of different stresses to the urinary tract. Under basal conditions no pelvic pressure increase was observed during detrusor contraction or other alteration of lower urinary tract pressure. However, after the flow in the upper tract was increased by oral water load, intravenous furosemide or direct pelvic perfusion, pelvic pressures were markedly elevated and reflected accurately any change in intravesical pressure. Under such conditions, pelvic pressures frequently exceeded 40 cm. water. These observations provide an explanation for the increasing size of the upper tract and a clarification of the mechanism whereby renal function might gradually deteriorate in these patients.