Urinary: Perfusion/Vascular

Question 1

Hypertension s/p renal biopsy

Answer 1

Page kidney (hypertension secondary to a sub capsular hematoma compressing the kidney)

Note: This occurs because the renal capsule does not expand.

Question 2

Delayed vs persistent nephrogram

Answer 2

A delayed nephrogram usually only affects one kidney (due to pressure: obstruction, sub capsular hematoma, renal vein thrombosis, etc.)

A persistent nephrogram is usually bilateral and can persist for hours (seen with hypotension/shock and acute tubular necrosis)

Question 3

Wedge shaped renal hypodensity…

Answer 3

• Think renal infarction (if there is a rim of cortical enhancement)
• Think pyelonephritis (if hypodensity extends through the cortex to the edge, no “cortical rim” sign)

Question 4

Cortical rim sign

Answer 4

A rim of enhancing tissue peripheral to a wedge-shaped renal hypodensity, suggesting infarction rather than pyelonephritis (due to the dual blood supply of the cortex)

Note: The cortical rim sign takes 8 hours-multiple days to show up and will not be present immediately after infarction.

Question 5

Reversed diastolic flow in the renal artery and absent venous flow…

Answer 5

Renal vein thrombosis

Question 6

Common causes of renal vein thrombosis

Answer 6

• Nephrotic syndrome (most common in adults)
• Dehydration
• Indwelling umbilical venous catheters (neonates)

Question 7

CT findings of renal vein thrombosis

Answer 7

Unilateral enlarged kidney with a delayed nephrogram

Question 8

Answer 8

Acute cortical necrosis

Note: Relative hypodensity of the renal cortex (“reverse cortical rim” sign).

Question 9

Common causes of acute cortical necrosis

Answer 9

Severe hypovolemia:

• Shock
• Intravascular hemolysis
• OBGYN complications (e.g. placental abruption)