hydronephrosis

noun

hy·​dro·​ne·​phro·​sis -ni-ˈfrō-səs 

plural hydronephroses -ˌsēz 

: cystic distension of the kidney caused by the accumulation of urine in the renal pelvis as a result of obstruction to outflow and accompanied by atrophy of the kidney structure and cyst formation