Acute kidney injury, formerly called acute renal failure, is a rapid decrease in the kidneys’ ability to filter waste products from the blood. Ultrasound plays an important role in evaluating patients with acute kidney injury by helping determine whether the cause is an obstruction, such as a kidney stone blocking the ureter, which would show up as hydronephrosis. The sonographer assesses kidney size, cortical thickness, echogenicity, and the presence or absence of obstruction in the collecting system. While many causes of acute kidney injury are not visible on ultrasound, ruling out obstruction is a critical first step in guiding treatment.
Sonography Term