KEY FACTS
Terminology
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Perigraft fluid collections include hematomas, seromas, urinomas, lymphoceles, and abscesses
Imaging
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US is 1st-line modality for evaluating renal transplants; excellent for fluid collections
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Collections of variable size and echogenicity, typically walled off due to extraperitoneal placement of kidney
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Anechoic fluid suggests seroma, lymphocele, or urinoma
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Fluid with internal echoes or septations suggests hematoma or abscess
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Definitive diagnosis established by US-guided needle aspiration as well as therapeutic drainage
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Aspirate should be tested for creatinine, which is markedly elevated in urine leak, and for infection
Top Differential Diagnoses
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Ovarian and renal cysts
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Penile prosthesis reservoir
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Peritoneal inclusion cyst
Clinical Issues
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Large collections may compress transplant ureter resulting in hydronephrosis or may compress kidney, causing graft dysfunction
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Small hematomas and seromas are common and usually resolve spontaneously
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Lymphoceles occur in 5-15% patients, usually after 4 weeks; majority are asymptomatic but can be slow growing
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Urinomas occur in 2-5% of patients; within first 2 weeks, secondary to anastomotic leak or ureteric ischemia
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Pain, swelling, discharge from wound, and elevated serum creatinine; intervention required
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Abscesses: Fever, abdominal pain, raised white cell count
Scanning Tips
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Color Doppler to assess for active bleeding
. The allograft is well perfused despite a large, acute, echogenic perinephric hematoma 
.
. The transplant ureter was compressed by a large lymphocele 
, and a ureteral stent is present 
.
. There was a large lymphocele 
anterior and posterior to the transplant, encircling vessels 
.
