The right kidney is normal in appearance, with a relatively hypoechoic cortex, and a more echogenic medulla including medullary fat and inapparent collecting system. You need to know how sagittal images are oriented in order to interpret them. The head, by convention, is always to the LEFT of the image, and feet to the RIGHT.

The left kidney also has a hypoechoic cortex, but the calyces and renal pelvis are enlarged and full of urine, indicating hydronephrosis. Water and all liquids (like urine, bile, blood) are very dark on ultrasound, which is different from other imaging modalities.

head

feet