Three small stones in right kidney, which not causing any problem (Non obstructing). Two small stones in left kidney, which are also not creating any problem but two stones of significant size, present in left lower ureter, causing obstruction, means not allowing urine from left lotto flow without any blockage, thatwhy upstream ureter and kidney become swollen up ( Hydro-ureteronephrosis & hydronephrosis). In short left side ureteric stones require surgical stone removal, less likely to pass automatically. And same time left renal stone can be removed so at least one kidney become stone free. I think it will be enough.