Patients with hydronephrosis should pay attention to care if a drainage tube is placed. Specific care is as follows: 1. When ureteral stents need to be left in place for pyeloureteroplasty, they should be removed 4-6 weeks after surgery; adult patients should be removed under outpatient cystoscopy, children should be removed 7-12 days, nephrostomy ureteral stent drainage tubes should be removed 4-6 weeks, and perinephric drainage tubes should be removed 2-3 days after removal of nephrostomy ureteral stent drainage tubes; 2. Infection needs to be prevented during out-of-hospital tube carrying period, which can be done 6 months after surgery. During the period of retaining the drainage tube, it is recommended to drink more water every day to acidify the urine and dilute the crystals in the urine, which can prevent the crystals from being adsorbed on the surface of the ureter wall and forming urine salt deposits, thus blocking the drainage tube and causing poor drainage of urine.