Clinical Scenarios in Acute Kidney Injury-Parenchymal Acute Kidney Injury - Vascular Diseases.

Acute cortical necrosis and hemolytic uremic syndrome (HUS) are 2 clinical scenarios of parenchymal acute kidney injury (AKI) related to renal microvascular injury. Acute cortical necrosis is a rare condition related to an ischemic necrosis of renal cortex. Necrotic lesions can be due to several injuries and may be focal, multifocal or diffuse. Renal necrotic lesions become visible with ultrasound only after renal recovery. HUS is a rare disease characterized by hemolytic anemia, thrombocytopenia and AKI. Color Doppler ultrasound is useful during diagnostic and follow-up phase. Renal artery thrombosis and renal vein thrombosis may also cause parenchymal AKI. Acute renal infarction is a rare pathological condition that occurs due to clots or cholesterol aggregates occluding renal artery or its branches. Several causes may lead to partial or massive kidney ischemic necrosis. Contrast-enhanced CT allows definitive diagnosis in 80% of cases and, at present, it is the first imaging technique used. Ultrasound (US) sensitivity and specificity significantly increases with color Doppler and contrast-enhanced US (CEUS). In AKI patients, in whom the use of iodinated contrast media is contraindicated, color Doppler and CEUS may be valid alternatives for the diagnosis of acute renal infarction. Renal vein thrombosis may be primary or secondary to retroperitoneal neoplasm or inflammatory diseases. It rarely causes an acute worsening of renal function because of the presence of several anastomosis that prevent parenchymal necrosis due to venous congestion. Color Doppler US could detect thrombus within the lumen and document the absence of venous flow.