Examination of a fresh urine specimen provides the best results. If a specimen cannot be examined immediately, it may be refrigerated for up to 12 hours. Refrigeration prevents decomposition of casts, cells and the overgrowth of bacteria. The urine sediment elements begin to lyse after 1-3 hours at room temperature.

Although the most commonly received urine specimen is the random urine collection, the specimen of choice for urinalysis is the first morning urine. The first morning urine is more concentrated and allows for the detection of substances which may not be present in a more dilute random sample.

Once the physical and chemical characteristics of the urine have been determined, the microscopic exam is performed on the sediment.