Hubungan derajat hidronefrosis dan leukosit urin terhadap komplikasi demam dan retropulsi pada batu non-opaque yang dilakukan ureteroskopik lithotripsi di RSUD dr. Fauziah Bireuen = Relationship between grade of hydronephrosis and urine leucocyte with fever and retropulsion as complication of ureteroscopic lithotripsy in patients with non opaque stone