Table : US Characteristics of Normal Kidneys

Feature Normal Characteristic Size Length: Adult: 9-13 cm (decreases with age) Male: 11.4 cm median length Female: 10.9 cm median length Volume: (length × width × height × 0.52) Adult: Male: range: 109-194 mL 151 mL median volume Female: range: 91-151 mL 122 mL median volume Parenchymal thickness: Normal >10 mm Echogenicity of cortex Adult: renal parenchyma echogenicity equal to, or slightly less than, normal liver parenchyma Neonate: renal parenchyma echogenicity usually greater than normal liver parenchyma Echogenicity of medulla Adult: slightly less than renal cortex Neonate: much less than renal cortex Surface Smooth, well-defined, slightly lobulated with V-shaped notches between lobes Peak systolic velocity in main renal artery Normal <180> Renal/aortic velocity ratio Normal <3.5 Resistive index–intrarenal arteries and main renal artery Adult: Normal <0.70>0.70 Systolic rise time (time to early systolic peak) in main renal artery

Normal Newborn Infant Kidney. Longitudinal view of the normal right kidney (between cursors, +, x) of a newborn infant demonstrates echogenicity of the cortex to be slightly greater than the echogenicity of the liver (L). The medulla (arrows) is significantly less echogenic.

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Normal Adult Kidney. The renal cortex (short arrow) is equal in echogenicity to the liver parenchyma (l). The renal pyramids (long arrow) are slightly hypoechoic compared to the renal cortex. The septal cortex extends between the medullary pyramids. The central renal sinus (s) is invested with echogenic fat. The contour of the kidney is sharply defined by fat in the perirenal space. The length of the kidney is measured between cursors (+).

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