After removing the catheter there are impurities discharged from the urine to consider the metabolites produced by bacterial infection or crystals formed by substances left in the urine in the urinary catheter. 1. urinary tract infection: urinary tract infection is a metabolite produced by bacterial infection in the urine, the formation of impurities in the urine, if it is a urinary tract infection or appropriate according to the results of the drug sensitivity to select sensitive antibacterial drugs, such as levofloxacin capsules, cefuroxime, clindamycin and other drugs to fight infection treatment. 2. Urinary catheter crystallization: After the urinary catheter is placed for a long time, the substances in the urine will become crystallized in the urinary catheter, that is, the stones, the crystals fall in the bladder, so when the catheter is removed, the smaller stones in the urine will be discharged with the urine. After removing the catheter if there are impurities in the urine discharged should go to the hospital to do routine urine examination, to clarify whether there is a urinary tract infection, choose the appropriate treatment program.