Answer 5

5.  Choice C is the correct answer.  Renal ultrasound is the modality of choice.  It has the lowest exposure to radiation, and highest yield.  It is important to note you do not actually see the kidney stone, but you will see the associated hydronephrosis and ureter dilation.  CT scan of abdomen and pelvis without contrast in the non pregnant patient is the ideal test, but is too much radiation exposure when other tests are available.  KUB will have some minimal radiation, but will be low yield.  MRI of the Abdomen and Pelvis is not an ideal modality because of cost and will have virtually radiation exposure.