Hydronephrosis refers to the accumulation of urine in parts such as the renal pelvis and calyces due to some reason causing the urinary system to not smoothly excrete urine. After the kidneys produce urine, it cannot be excreted smoothly, leading to the accumulation called hydronephrosis. Generally, it is necessary to visit the urology department, as the most common causes of hydronephrosis are stones or tumors in the urinary system and prostatic hyperplasia, among other issues, all of which require urological treatment. In most cases, surgery may be necessary to relieve the obstruction and resolve the hydronephrosis. However, there are also a small number of patients who may have hydronephrosis due to other reasons, such as cervical cancer or colorectal cancer patients, where enlarged tumors may compress the ureter leading to hydronephrosis. Patients with cervical cancer need to undergo surgical treatment in gynecology, while those with colorectal cancer may need treatment in general surgery.