Urine contains waste products that are removed from the blood by the kidneys and liver. Routine screening of urine often helps to identify serious disease such as diabetes, kidney and liver disease and infection of the urinary tract. The sample can be collected by two methods –free flow (or voiding) or cystocentesis. Collected urine samples should be evaluated within 30 min of collection, but if this is not possible, it may be refrigerated.