What is a typical appearance of kidney stones on ultrasound?

The typical appearance of kidney stones on ultrasound is hyperechoic with acoustic shadowing. This characteristic arises because kidney stones are dense calcifications that reflect ultrasound waves effectively, resulting in a bright (or hyperechoic) image. The acoustic shadowing occurs because the stone blocks the ultrasound waves, leading to an area of decreased echogenicity behind it where the sound waves cannot penetrate. This shadow is a key diagnostic feature that helps in identifying the presence of stones during a sonographic examination.

Options suggesting hypoechoic with enhancement and isoechoic to renal cortex are not accurate for kidney stones. Hypoechoic lesions typically appear darker on ultrasound and could indicate fluid or certain types of tumors, not calcifications. Isoechoic lesions blend in with surrounding tissue, making them hard to distinguish, which does not apply to the highly reflective nature of kidney stones. Finally, completely anechoic areas are indicative of fluid-filled structures, such as cysts, and would not represent the solid, calcified material of a kidney stone. Thus, the answer highlights the distinct ultrasound characteristics of kidney stones crucial for accurate diagnosis.