I think the information that you have given is good enough to give an opinion. A majority of mild hydronephrosis due to VU junction obstruction DO NOT need surgery as they usually stabilize. Surgery is indicated only if the hydronephrosis/hydroureter is increasing, or the kidney function shows evidence of deterioration. You really need to have a good opinion with review of all the films before you plan for surgery. Meanwhile, it may be a good idea to get a DTPA renal scan done.