Contained rupture secondary to defect in artery wall

Usually in renal parenchyma, rarely extrarenal

Usually ≤ 1 cm

Extrarenal pseudoaneurysm may be larger

Saccular, round or ovoid lesion

Mimics simple or complex renal cyst on grayscale but with pulsations or swirling internal echoes

Doppler: High-velocity jet into sac with internal turbulent flow

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  Swirling yin-yang internal flow

  
  
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  To-and-fro waveform in neck

Internal clot when large

CTA/MRA are confirmatory tests, which provide additional information about entire arterial tree

Cyst

Arteriovenous fistula, may coexist with pseudoaneurysm

Perinephric collection (extra renal pseudoaneurysm)

Intrarenal: Iatrogenic injury during biopsy or percutaneous procedure

Most asymptomatic

Hematuria, abnormal renal function

Pain, bleeding/hypotension from rupture

Increased risk of rupture when extrarenal and > 2 cm

Always turn on color Doppler when evaluating renal cystic lesions

Look for characteristic to-and-fro flow in neck