Patients with hydronephrosis should visit the urology department of a formal hospital, because the conditions causing hydronephrosis are often surgical in nature. The most common cause is urological stones, which block the ureter or the bladder opening, causing urine to accumulate within the urinary system and leading to hydronephrosis. Additionally, patients with benign prostatic hyperplasia may also experience this condition. Tumors in the urinary system may compress the ureter and cause hydronephrosis. Some patients have congenital deformities of the ureter, where changes in the anatomical structure can lead to hydronephrosis. In summary, these conditions often require surgical treatment, thus necessitating consultation at a formal hospital's urology department.