Pressure Atrophy Atrophy of the kidney o Due to hydronephrosis which presents distension and dilation of the renal pelvis and calyces,usually caused by obstruction. o This increased pressure within the renal pelvis and calyces results in renal parenchyma atrophy (renal cortex or medulla). Atrophy due to hydronephrosisPressure Atrophy Atrophy of the kidney  Due to hydronephrosis which presents distension and dilation of the renal pelvis and calyces, usually caused by obstruction.  This increased pressure within the renal pelvis and calyces results in renal parenchyma atrophy (renal cortex or medulla). Atrophy due to hydronephrosis