Urine Specimen Types, Collection, and Preservation

Why is urine studied?

Urinalysis is a non-invasive way to evaluate the kidneys, body homeostasis, metabolic diseases, and treatment effectiveness.

What is urine?

Urine is an ultrafiltrate of plasma

Why is urine a useful specimen?

It is usually readily available and can provide information about kidney function and overall health.

What type of container is recommended for urine collection?

A disposable, wide-mouthed, flat-bottomed container with a cap.

What should a urine container be like?

Clear and able to hold at least 50 mL.

What type of container is needed for urine cultures?

A sterile container

What type of container is used for a 24-hour urine collection?

A large plastic container.

What can be used to collect urine from pediatric patients?

Adhesive plastic urine collection bags.

What information should be on a urine specimen label?

Patient’s name, unique identification number, and date and time of collection.

What additional information may be included on the label?

Date of birth and ordering physician.

Where should the specimen label be placed?

On the container, not the lid.

What information should accompany a urine specimen?

A requisition form.

What information should match between the specimen and requisition?

Patient identification and specimen information.

What is a first-morning urine specimen?

Urine collected first thing in the morning after the bladder was emptied before going to bed.

Why is first-morning urine often preferred?

Why is first-morning urine often preferred?

What is first-morning urine commonly used for?

Routine screening.

What can affect a random urine specimen?

Excess fluid intake or exercise.

What is a random urine specimen?

A urine specimen collected at any time without special timing.

What is a timed urine specimen?

A urine collection performed over a predetermined period of time or at a specified time of day.

What is routine voided urine?

Urine collected when the patient voids directly into an appropriate container.

Does routine voiding usually require patient preparation?

No

What types of specimens can be collected by routine voiding?

Random or first-morning specimens.

What is a midstream clean-catch specimen?

A urine specimen collected from the middle portion of urination after cleaning the genital area.

Why is a clean-catch specimen collected?

To reduce contamination and for bacterial cultures.

How is a clean-catch specimen collected?

Clean the genital area, begin urinating into the toilet, collect the midstream urine in the container, and finish voiding into the toilet.

What does a clean-catch collection require?

Cleaning supplies, patient instructions, and a sterile container.

What is a catheterized specimen?

Urine collected by inserting a sterile catheter through the urethra into the bladder.

Who collects a catheterized specimen?

Medical personnel.

Where does urine go during catheterization?

Directly into a collection bag.

What is a catheterized specimen commonly used for?

Culture and sensitivity

What is suprapubic aspiration?

A procedure where a needle and syringe collect urine directly from the bladder through the abdominal wall.

Who performs suprapubic aspiration?

Medical personnel

Why is suprapubic aspiration used?

Mainly for cultures, infants, or when catheterization is not possible.

Why is bladder urine useful for cultures?

Urine in the bladder is normally sterile.

How is urine commonly collected from pediatric patients?

Using a plastic urine collection bag attached with hypoallergenic adhesive.

What should be done before attaching a pediatric urine bag?

Clean the patient’s perineal area.

When should a pediatric urine bag be removed?

As soon as possible after urine is collected.

What type of testing is a pediatric bag specimen appropriate for?

Routine testing.

What are timed urine collections commonly performed over?

12 or 24 hours.

Why might a chemical preservative be added to a timed urine collection?

To maintain the integrity of the analyte being tested.

How does a timed urine collection begin and end?

It begins and ends with an empty bladder.

What happens to the first void in a timed urine collection?

It is discarded

How should a timed urine specimen be stored during collection?

On ice or refrigerated.

How do you know which preservative to use for a timed collection?

Check the laboratory collection manual.

When should a completed timed urine specimen be delivered to the laboratory?

Immediately after the collection period ends.

Why are timed urine specimens more accurate than random urine for some tests?

They provide a more accurate measurement of urine chemistry over a specific period.

What must be documented for drug specimen collection?

Proper collection, labeling, and handling.

What is chain of custody?

Documentation tracking the specimen from collection through receipt of laboratory results.

Why is chain of custody important?

It ensures the specimen can withstand legal scrutiny and has not been tampered with.

What accompanies a drug specimen?

A standardized form.

What identification may be required for a drug specimen donor?

Photo ID or identification by the employer.

What must not happen to a drug specimen?

Unauthorized access, adulteration, substitution, or dilution.

What is a witnessed drug collection

A collection where an authorized person directly observes the collection.

What is an unwitnessed drug collection?

A collection where the collector does not directly observe the urine being produced.

Who determines whether a drug collection is witnessed or unwitnessed?

The individual ordering the test.

When must the temperature of a drug specimen be checked?

Within 4 minutes of collection.

What is the acceptable temperature range for a drug urine specimen?

32.5–37.7°C.

What should be done if a drug specimen temperature is outside the acceptable range?

Report it immediately and collect another specimen as soon as possible.

What should be inspected in a drug specimen besides temperature?

The urine color for anything unusual.

Why might urine creatinine help identify urine?

Urine creatinine concentrations are about 50 times higher than plasma.

Which substances are higher in urine than in other body fluids?

Urea, sodium, and chloride.

What is the normal urine specific gravity range?

1.002–1.035.

What is the normal urine pH range?

4.0–8.0.

What substances are normally absent from healthy urine?

Protein and glucose.

Why might a urine specimen be rejected?

Because of improper labeling, contamination, insufficient quantity, improper transport, or improper storage.

What labeling problems can cause specimen rejection?

An unlabeled container or a mismatch between the label and requisition.

What types of contamination can cause specimen rejection?

Stool, toilet paper, or contamination on the outside of the container.

What transportation problems can cause specimen rejection?

Delayed or improper transport.

What storage problem can cause specimen rejection?

Failure to refrigerate when required.

How long should urine ideally be tested after collection?

Within 2 hours.

What should be done if urine testing is delayed?

Refrigerate the specimen or use an appropriate chemical preservative.

What causes most problems in unpreserved urine?

Bacterial growth.

What happens to urine color when it is left unpreserved?

It may become darker or change due to oxidation or reduction of metabolites.

What happens to urine clarity when it is left unpreserved?

Clarity decreases because of bacterial growth and precipitation of amorphous material.

What happens to urine odor when it is left unpreserved?

Odor increases because bacteria multiply and break down urea into ammonia.

What happens to urine pH when it is left unpreserved?

pH increases because bacteria break down urea into ammonia and CO₂ is lost.

What happens to glucose in unpreserved urine?

Glucose decreases because of glycolysis and bacterial use.

What happens to ketones in unpreserved urine?

Ketones decrease because of volatilization and bacterial metabolism.

What happens to bilirubin in unpreserved urine?

Bilirubin decreases because of light exposure and photooxidation.

What happens to urobilinogen in unpreserved urine?

Urobilinogen decreases because it oxidizes to urobilin.

What happens to nitrite in unpreserved urine?

Nitrite increases because nitrate-reducing bacteria multiply.

What happens to RBCs, WBCs, and casts in unpreserved urine?

They decrease because they disintegrate, especially in dilute alkaline urine.

What happens to bacteria in unpreserved urine?

Bacteria increase because they multiply.

What are the main effects of delayed urine testing?

Increased or changed color, turbidity, pH, nitrite, bacteria, and odor, with decreased glucose, ketones, bilirubin, urobilinogen, RBCs, WBCs, and casts.

Why is urine refrigerated?

To slow bacterial growth and preserve the specimen.

What type of specimen requires refrigeration for culture?

Culture specimens.

What can refrigeration do to urine?

Increase specific gravity and cause precipitation of amorphous crystals.

What should be done before chemical testing of refrigerated urine?

Allow the urine to return to room temperature.

What are chemical preservatives used for?

To maintain the integrity of urine when testing is delayed.

What are commercial transport tubes?

Tubes designed to help preserve and transport urine specimens.

What is important when choosing a chemical preservative?

It must be compatible with the chemical testing being performed.

What are the characteristics of an ideal urine preservative?

It should kill bacteria, inhibit urease, and preserve formed elements.