Pre-conception physical exams, pre-marital physical exams, and IVF pre-screening all require urine tests for routine urinalysis, and many women hastily leave urine for testing, resulting in various abnormal test results. Here we will briefly explain several precautions for urine testing. 1, avoid the 3 days before and after the menstrual period. Because the menstrual period to leave urine, easily mixed with menstrual blood, resulting in urine routine results show positive red blood cells, can not be distinguished from pathological hematuria. 2. Avoid retaining urine on an empty stomach. The urine retained when hungry often has ketone bodies, which is physiological. It is recommended that urine be retained half an hour after eating. 3.Pay attention to cleanliness. Because the urethral opening is very close to the vaginal opening, it is easy to mix vaginal secretions when retaining urine, so it is recommended to wipe the vulva with a tissue before retaining urine. 4. Retain the middle part of the urine. In order to further reduce the interference of vaginal secretions, please discard the initial section of urine and start to receive urine from the middle, and the latter section should also be discarded. 5.Usually, 30ml of urine can be retained.