Diagnostic Ultrasound - Abdomen and Pelvis

Perinephric Hematoma
TERMINOLOGY
Definitions
• Hemorrhagic collection in perinephric spaces: Subcapsular,
perirenal, anterior and posterior pararenal
IMAGING
General Features
• Best diagnostic clue
○ Avascular solid or cystic masses in 1 or more perinephric
spaces
– Echogenicity of blood changes over time
Ultrasonographic Findings
• Grayscale ultrasound
○ Sonographic features vary over time
– Acute: Highly echogenic perinephric mass
– Subacute: Partial liquefaction, echogenic debris,
retractile clot with thick septa
– Chronic: May be almost anechoic
• Color Doppler
○ Useful to assess perfusion in compressed kidney
○ Subcapsular collection will indent and compress renal
contour, causing Page kidney
○ Sometimes reveals etiologies such as pseudoaneurysm
○ No vascular flow within hematoma
CT Findings
• CECT
○ Highly sensitive for detection of perinephric fluid
collection, its extent, and underlying causes
○ In trauma or suspected active bleeding: Delayed images
to evaluate for pooling of extravasated vascular or
excreted urinary contrast
○ Hematoma: High attenuation (> 28 HU) may show
hematocrit level
Imaging Recommendations
• Best imaging tool
○ CT is diagnostic method of choice
○ US is ideal adjunct to CT and can guide aspiration to
determine nature of fluid collection
• Protocol advice
○ US is initial investigation for perinephric fluid collection
and guided aspiration
○ CT is required to identify cause of perinephric hematoma
or characterize fluid collections
○ Angiography is offered for superselective embolization
of bleeding tumor
○ For suspected occult renal cell carcinoma (RCC) as cause
of hematoma, consider follow-up ± biopsy by US or CT
DIFFERENTIAL DIAGNOSIS
Lymphoma Infiltration
• Lymphoma may completely encircle kidney, producing
hypoechoic collar
Cystic Lymphangioma
• Multilocular cystic lesion, occurs anywhere in
retroperitoneum
Perinephric Abscess
• Subacute complication of pyelonephritis; difficult or
impossible to differentiate from hematoma by US
PATHOLOGY
General Features
• Etiology
○ Causes include trauma, renal biopsy, renal tumor
rupture, renal cyst rupture, anticoagulant therapy, aortic
aneurysm rupture
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Flank pain, often severe, palpable mass, shock
• Other signs/symptoms
○ Diminished hematocrit may prompt evaluation
○ Subcapsular hematoma may cause hypertension
Natural History & Prognosis
• Hematoma without underlying significant pathology
usually resolves spontaneously with good prognosis
Treatment
• Subcapsular or perinephric hematoma: Treatment varies
with etiology
○ Extrafascial nephrectomy for malignant tumors or
extensive hemorrhage
○ Superselective embolization or covered stent for active
bleeding with clinical instability
○ Managed conservatively in benign entities
DIAGNOSTIC CHECKLIST
Consider
• Must identify underlying etiology in spontaneous
perinephric hematoma to exclude malignancy
Image Interpretation Pearls
• US provides noninvasive means of assessing fluid collection
resolution over time
SELECTED REFERENCES
1. Kozminski MA et al: Symptomatic Subcapsular and Perinephric Hematoma
Following Ureteroscopic Lithotripsy for Renal Calculi. J Endourol. ePub, 2014
2. Lee SW et al: Experience of ultrasonography-guided percutaneous core
biopsy for renal masses. Korean J Urol. 54(10):660-5, 2013
3. Sunga KL et al: Spontaneous retroperitoneal hematoma: etiology,
characteristics, management, and outcome. J Emerg Med. 43(2):e157-61,
2012
4. Chan YC et al: Management of spontaneous and iatrogenic retroperitoneal
haemorrhage: conservative management, endovascular intervention or
open surgery? Int J Clin Pract. 62(10):1604-13, 2008
5. Shih WJ et al: Spontaneous subcapsular and intrarenal hematoma
demonstrated by various diagnostic modalities and monitored by
ultrasonography until complete resolution. J Natl Med Assoc. 92(4):200-5,
2000
Diagnoses: Urinary Tract
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