Urine specimen collection methods and handling

Proper collection and handling of a urine specimen is what makes the rest of the urinalysis trustworthy. This chapter covers the main collection methods you’ll encounter as a medical assistant - the 24-hour collection and the clean-catch midstream specimen - along with how to handle and transport a specimen once it’s collected so its results stay accurate.

24-hour specimen collection

A 24-hour urine specimen is collected over 24 hours to provide a quantitative chemical analysis, such as hormone levels and creatinine clearance rates. The patient must understand the proper way to collect a 24-hour urine specimen.

Patient instructions for an at-home 24-hour urine collection are as follows:

• Do not put anything but urine into the container.
• Do not pour out any liquid or powdered preservative from the container.
• If you accidentally spill some of the preservative on yourself, immediately wash with water and call the POL, provider’s office, or testing laboratory.
• Always keep the collection container cool. Refrigerate the container or keep it in an ice-filled cooler or pail.
• Keep the cap on the container.

Clean-catch midstream specimen collection

A clean-catch midstream specimen (CCMS) is ordered when the provider suspects a urinary tract infection. When a UTI is possible, the provider will order a urine culture and sensitivity (C&S). For a C&S procedure, the specimen is cultured on microbiological media to detect bacterial or fungal growth. This is followed by screening the bacteria that grows for antibiotic sensitivity. A C&S is performed in the microbiology department of a referral laboratory, while a routine dipstick urinalysis is CLIA-waived and can be performed right in the POL - this distinction is what determines which test the medical assistant can run in-house versus which one must be sent out.

The clean-catch technique is used to eliminate microorganisms from the urinary meatus (the external opening of the urethra). In the medical facility, collecting CCMS samples starts by instructing the patient to thoroughly cleanse around the meatus and then micturate (urinate) a small amount into the toilet. This is done to flush out the distal portion of the urethra, where normal flora can accumulate. The patient then collects a CCMS specimen. Prior to collection, the medical assistant needs to give complete, understandable instructions to the patient on the method of collection. Failure to do so may mean that the patient will have to return to the office to provide another specimen. For a urine C&S, the urine is collected either by catheterization or the clean-catch method into a sterile container.

When both a routine urinalysis and a C&S are ordered on the same specimen, handle the sterile portion first: pour off or aliquot the amount needed for culture into the sterile culture container before performing any routine urinalysis testing on the remaining sample. Testing the routine UA first risks contaminating or using up the portion that needs to stay sterile for culture.

Handling and transporting a specimen

Proper handling of specimens is essential. The chemical and cellular components of urine change if the urine warms to room temperature. Urine specimens should therefore be tested within 1 to 2 hours of collection. A specimen that cannot be tested in that time should be refrigerated. If the specimen must be transported to a referral laboratory, evacuated transport tubes are available. These tubes contain preservatives and look like blood collection tubes. The preservatives in the tube prevent the overgrowth of bacteria and will prevent chemical changes in the urine that may affect test results. Chemical reagent strip testing can be performed on preserved specimens within 72 hours. Tubes may be held at room temperature during this time.

A different preservative must be used for urine culture specimens. The preservative used for culture specimens helps maintain the number of bacteria present at the time of collection. This type of transport system should be used only for urine specimens that will be cultured. Results on the chemical reagent strip may be altered by the alternative preservatives. Culture and sensitivity testing should be performed within 72 hours. The C&S tubes can be held at room temperature.

A laboratory request form (paper or electronic) must be completed for every specimen sent to another site for analysis, and typically includes the patient’s name and date, the type of urinalysis ordered, the ordering provider’s name, the appropriate ICD-10 diagnosis code (and, if included, the CPT code for the test ordered), and the ordering provider’s signature authorizing the test.

Changes in urine at room temperature

Constituent	Change
Clarity	Urine becomes cloudy as crystals precipitate and bacteria multiply
Color	May change if pH becomes alkaline
pH	Becomes alkaline as bacteria form ammonia from urea
Glucose	Decreases as it is metabolized by bacteria
Ketones	Decrease because of evaporation
Bilirubin and urobilinogen	Undergo degradation in light
Blood	May hemolyze; false-positive results are possible because of bacterial enzymes
Nitrite	Test result may change from negative to positive as bacteria multiply and reduce nitrates to nitrites
Casts	Lyse or dissolve in alkaline urine
Cells	Lyse or dissolve in alkaline urine
Bacteria	Multiply twofold approximately every 20 minutes
Yeasts	Multiply
Crystals	Precipitate as urine cools; may dissolve if pH changes

• Always handle specimens by the container and not the lid to avoid accidental spills

Specimens are sent to the laboratory in a plastic biohazard bag that zips closed and has an outside pocket, where a paper laboratory request is placed if the order has not been placed in the electronic medical record, and the specimen is labeled with the appropriate order information. After the test has been performed, the lab physically sends a paper report or electronically sends the results to the provider.

Components of physical and chemical urinalysis

Physical property	Chemical component
Color	Protein
Clarity	Glucose
Specific gravity	Ketones
Volume	Bilirubin
Odor	Blood
Foam	Nitrite
	Urobilinogen
	Leukocyte enzyme