Sonography of Urolithiasis and Hydronephrosis

Urolithiasis, the presence of renal calculi within the urinary tract, is the most common cause of extrarenal obstructive uropathy. Following a review of normal anatomy and sonographic technique, this article focuses on urolithiasis as a disease process, its findings on ultrasound, and its effects on the kidney and the collecting system. The authors discuss the physiologic changes that accompany hydronephrosis following obstruction of the collecting system and the important causes to consider when presented with hydronephrosis.