2-Stage of decompensation

progressive urethral obstruction &presence of infection decompensation of the detrussor may occur result in

high residual urine may reach up to 500 ml or more.

Pathogenesis &Pathology:• Upper tract: 1-Ureter: -In early stage the intravesical pressure is not transmitted into the ureters because of the competence of the ureterotrigonal unit. -Later hypertrophy of trigone. -Vesicoureteral reflux. -Intravesical pressure transmitted to urete and pelvis. -Thickening and tourtiousity of the ureter.

2-The kidney: -The pressure in the renal pelvis is zero. -Increase pressure due to obstruction or reflux lead to hydronephrosis> Stage of compensation: Stage of decompensation:

• Effect of hydronephrosis on the kidney: 1-The early changes: The end of the normal calyx is concave with increase

pressure it becomes convex(clubbed). Changes in the parenchyma are due to: a-Compression atrophy. b-Ischemic atrophy mainly manifested in arcuate vessels that run at the base of the pyramid.