I had larascopic pyeloplasty right kidney march 2014 for puj obstruction.. it was a success but within 6 months i have hydronephrosis again. why?

Maybe OK: You still may have some degree of dilation of the renal pelvis even after corrective surgery for UPJ obstruction depending upon how much dilation was present to start. The crucial piece of information is how well your kidney actually empties, usually defined by a test such as a Lasix (furosemide) renal scan/renogram. As long as the kidney empties with Lasix (furosemide) challenge, some dilation is not a problem.