Describe typical findings on an ultrasound of the urinary tract.

Kidneys: smooth in outline; 9 to 13 cm long in adults
Renal cortex: homogenous echoes that are less echogenic than the adjacent liver or spleen
Renal pyramids: triangular sonolucent areas adjacent to the renal sinus (not to be mistaken for hydronephrosis)
Ureters: not usually visualized (a calculus may be visualized in the UVJ)
Urinary bladder: examine while distended; walls sharply defined and barely perceptible

D, diaphragm; L, liver; U, upper pole of the kidney; C, renal cortex; E, central echo complex (surrounded by parenchyma; contains fat, vessels, and the collecting system); P, renal pyramid.