Cystitis is easily induced after bladder instillation because of chemical stimulation, and symptoms of frequent urination, urinary urgency and painful urination can occur, which will usually be relieved after one week. In clinic, bladder and ureteral urothelial cancer need to be treated with bladder perfusion after surgery. Bladder perfusion generally in refers to the injection of chemotherapy drugs into the bladder to suppress the tumor and prevent recurrence. Chemotherapy drugs can stimulate the bladder to produce chemical cystitis resulting in frequent, urgent and painful urination, which usually recovers slowly in about a week. If the symptom of painful urination is more obvious, you can first suspend the bladder perfusion treatment, etc., improve the urine routine and other related examinations, give appropriate treatment, and then perform perfusion after the symptoms disappear.