Blood in urine many days after partial nephrectomy may be due to postoperative infection, urinary tract injury or urethritis. 1. Postoperative infection: the symptom of blood in urine after many days of partial nephrectomy may be caused by infection due to poor postoperative care, and when the infection is serious, the patient will also have abdominal pain, fever and other symptoms. 2. Urethral injury: during surgery, if the surgery is not performed properly it may lead to damage to the ureter, which is not effectively treated and may lead to blood seepage from the urinary tract, thus causing the symptom of hematuria. 3. Urethritis: Urethritis can cause patients to have painful urination, itchy urethra, foul-smelling discharge from the urethra, which is usually due to bacterial invasion of the urethra caused by inflammation, and when the symptoms are serious, it can cause patients to have blood in the urine. Hematuria after partial nephrectomy may also be caused by other factors, it is recommended that patients go to the regular hospital in time to avoid the deterioration of the condition.