For patients with indwelling catheters, it is recommended that the external drainage bag be changed every other week. Replacement can be done completely on your own, without the need to go to the hospital for replacement. Note: 1, use iodophor solution to disinfect the connection between the urethra and the drainage tube. 2, remove the drainage tube from the urethra, discard the used drainage bag after removal, take the new drainage bag and open it without touching the connection between the drainage tube and the urethra with your hands, and then insert the connection part of the drainage bag into the urethra. 3, after insertion, you need to insert it to a certain depth of about 3-4cm, which can ensure that the drainage bag is tightly connected with the urethra, and will not be dislodged or leak with movement. and the ureter is connected closely, will not lead to the drainage tube with the movement, leakage of urine occurs. 4, drainage bag replacement, check the drainage bag drainage urine is normal. If you do not see urine after replacement, you can gently press the patient’s abdomen to see whether there is urine in the drainage tube. If urine can be seen, it means that the replacement is successful and smooth; however, if there has been no urine drainage after the replacement, it is recommended to remove it and reinsert it or go to the hospital for further examination to see if there is any other abnormality.