Diagnostic Ultrasound - Abdomen and Pelvis

Renal Transplant Pseudoaneurysm
TERMINOLOGY
Abbreviations
• Pseudoaneurysm (PA)
Definitions
• Contained rupture secondary to defect in artery wall
IMAGING
General Features
• Best diagnostic clue
○ Focal outpouching from artery
• Location
○ Usually in renal parenchyma, rarely extrarenal
• Size
○ Usually ≤ 1 cm
○ Extrarenal PA may be larger
• Morphology
○ Saccular or fusiform
○ Narrow or wide neck
Ultrasonographic Findings
• Grayscale ultrasound
○ Mimics simple or complex renal cyst
○ Pulsations or swirling internal echoes
○ Internal clot when large
• Pulsed Doppler
○ High velocity jet into sac
○ Internal turbulent flow
○ To-and-fro waveform in neck
• Color Doppler
○ Swirling yin-yang internal flow
○ Aliasing in neck
Angiographic Findings
• Ovoid or spherical outpouching from artery
• May contain intraluminal thrombus
Imaging Recommendations
• Best imaging tool
○ Color Doppler sonography for screening
○ Angiography for confirmation and endovascular
intervention
• Protocol advice
○ Always turn on color Doppler when evaluating renal
cystic lesions
CTA and MRA
• Outpouching from arterial lumen enhancing during arterial
phase
• Provide more information about state of arterial tree as
well as size and morphology of pseudoaneurysm
• Noninvasive but require intravenous contrast
DIFFERENTIAL DIAGNOSIS
Cyst
• Anechoic, thin walled with posterior enhancement
• No flow on color Doppler
Arteriovenous Fistula
• May coexist with PA
• Low-resistance, high-velocity waveform
• Pulsatile draining vein
Perinephric Collection
• Cystic ± internal echoes
• Avascular
PATHOLOGY
General Features
• Etiology
○ Intrarenal: Iatrogenic injury during biopsy or
percutaneous procedure
○ Extrarenal: Surgical complication at anastomosis or
infection (mycotic)
○ Rarely secondary to trauma, inflammation, or neoplasm
in renal transplants
• Associated abnormalities
○ Arteriovenous fistula (AVF) or multiple PA
Microscopic Features
• Confined by organized thrombus or fibrous tissue
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Most asymptomatic
• Other signs/symptoms
○ Hematuria, abnormal renal function
○ Pain, bleeding/hypotension from rupture
○ Bruit or pulsatile mass if large
Demographics
• Epidemiology
○ Less frequent than AVF
○ Extrarenal < 1%
Natural History & Prognosis
• Smaller PA: Self-limiting with spontaneous thrombosis
• Larger or enlarging PA: More prone to rupture
Treatment
• Selective embolization
• Thrombin injection
DIAGNOSTIC CHECKLIST
Consider
• Increased risk of rupture when extrarenal and > 2 cm
Image Interpretation Pearls
• To-and-fro flow in neck is diagnostic of PA
SELECTED REFERENCES
1. Rodgers SK et al: Ultrasonographic evaluation of the renal transplant. Radiol
Clin North Am. 52(6):1307-24, 2014
2. Glebova NO et al: Endovascular interventions for managing vascular
complication of renal transplantation. Semin Vasc Surg. 26(4):205-12, 2013
3. Aktas S et al: Analysis of vascular complications after renal transplantation.
Transplant Proc. 43(2):557-61, 2011
4. Rivera M et al: Asymptomatic large extracapsular renal pseudoaneurysm
following kidney transplant biopsy. Am J Kidney Dis. 57(1):175-8, 2011
5. Jin KB et al: Delayed presentation of arteriovenous fistula and
pseudoaneurysms in a renal transplant patient 10 years after percutaneous
allograft biopsy. Transplant Proc. 40(7):2444-5, 2008
Diagnoses: Kidney Transplant
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