In the case of right hydronephrosis, ultrasound examination is needed to clarify the severity of the hydronephrosis. If it is a mild separation of the pelvis and calyces, this is not a serious stage, but the specific cause of the hydrocele needs to be clarified. If it is a right ureteral stenosis, dilation of the ureteral stenosis is needed. If the fluid is caused by a right ureteral stone, the stone needs to be crushed and expelled to relieve the fluid. If it is due to neurogenic bladder, urethral stricture, prostatic hyperplasia, as well as external vessels and ligaments jamming the ureter, including pelvic ureteral junction stricture, treatment of the primary disease is needed to alleviate the progression of hydronephrosis. If the examination reveals significant thinning of the kidney cortex and significant and severe effusion, this is a serious stage and blood tests are needed to clarify the creatinine urea nitrogen level. An assessment of unilateral renal function should also be performed. If the function of the divided kidney is significantly decreased, timely relief of obstruction, including double J-tube placement to drain the urine, is required. After relieving the hydronephrosis, the cause of the specific hydronephrosis will be clarified and treated.