Urine samples have the potential to become contaminated either by their own route or through the sample tube. If the area around the perineal skin is not cleaned when a urine sample is taken, there is a good chance that a large number of pathogens, such as viral or bacterial ones, will be present and may lead to contamination of the urine sample when it is collected. It is also possible that the sample tube, which is not strictly cleaned and sterilized, may lead to contamination of the urine sample. If a variety of pathogenic microorganisms can be cultured during the urine sample test, it may be caused by contamination of the urine when it is retained, and care needs to be taken to clean the perineum properly and re-retain the urine for testing.