The kidneys are a pair of bean-shaped organs located in the retroperitoneum, one on each side of the spine, responsible for filtering waste products from the blood, regulating fluid and electrolyte balance, and producing urine. On ultrasound, the normal kidney measures approximately 9 to 12 centimeters in length, with a bright echogenic central sinus surrounded by less echogenic cortical tissue that is normally equal to or slightly less echogenic than the adjacent liver or spleen. Renal ultrasound evaluates kidney size, shape, echotexture, the presence of cysts, masses, stones, and hydronephrosis, and Doppler assessment of renal blood flow. The kidneys are among the most commonly examined organs in diagnostic ultrasound.
Sonography Term