August 31, 2012

ESWL-induced Perinephric Hematoma

Ultrasound image of the kidney shows a crescentic heterogeneous hypoechoic lesion in the perinephric space (arrows). The kidney is marked by the calipers. 
Axial unenhanced CT images confirm a thick left perinephric hematoma (stars) and several fragmented stones in the lower pole of the left kidney.
  • ESWL (Extracorporeal Shock Wave Lithotrypsy) is a common and standard treatment for renal/proximal ureteric calculi in majority of patients
  • Most common complication = microscopic hematuria
  • Perinephric hematoma and infection (including pyelonephritis) can occur
  • Incidence of hematoma varies depending on method of diagnosis. By US, incidence is about 0.1-0.6%. By CT/MRI, incidence rises to 20-25% of cases. 
  • No clear correlation between number of shockwaves or intensity given and incidence of hematoma
  • Most perinephric hematoma resolves spontaneously within 2 years and the renal function is preserved. They are mostly treated conservatively
Imaging: US and CT
  • Crescent-shaped collection surrounding the affected kidney
  • Hypoechoic on US, hyperattenuating on non-contrast CT and no enhancement after IV contrast
  • Displacement or compression of adjacent renal parenchyma
  • Differentiate from subcapsular hematoma by appearance and pressure effect to underlying kidney.
  • "Page" kidney occurs when (usually) subcapsular hematoma causes chronic renal parenchymal compromise and then hypertension

Labanaris AP, Kuhn R, Schott GE, Zugor V. Perirenal hematomas induced by extracorporeal shock wave lithotripsy (ESWL). Therapeutic management. TheScientificWorldJOURNAL 2007;7:1563-1566.

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