There are two possible conditions of right hydronephrosis on ultrasound. The first is a potty pelvis, where the width of the pelvis is greater than 1 cm, but the calyces are still flared, which is not a true hydronephrosis and does not require treatment. The second condition is true hydronephrosis due to stones, stenosis, tumors, or posterior vena cava ureter. The identification of the two requires intravenous pyelogram, and if the kidney is poorly visualized, retrograde pyelogram will be added to make a clear diagnosis and then targeted treatment.