General Laboratory Guidelines

Refer to the University of Colorado Hospital Clinical Laboratory Test Catalog for the most current and complete specimen collection and testing information:

Test Catalog

Need to collect and send specimens to Cytology, Histology, or Surgical Pathology?  Go to the UCD Pathology  page.

Cerebrospinal fluid specimens

Spinal fluid tubes are properly labeled with the patient’s name and medical record number and identified with sequential numbers: #1, #2, #3, and #4. Default testing for each tube is as follows:

#1 Cell counts (appearance, color, RBC, nucleated cells)

#2 Cultures (viral, bacterial)

#3 Chemical tests (glucose, lactate, LDH, protein, etc.)

#4 Cell counts/other (repeat cell count especially if #1 is bloody, additional volume for repeat or additional testing such as VDRL, oligocolonal banding, West Nile virus serology, and others)

Ideally, CSF specimens should consist of these four (4) tubes each containing 2-3 ml of fluid. This will provide enough sample to perform multiple tests with adequate volume for repeat analysis and add-on tests. To ensure the best patient care, if at all possible, CSF samples should be submitted in this manner.

Under extreme circumstances, a bare minimum of two (2) tubes each containing 2-3 ml of CSF can be submitted. This often provides sufficient sample to perform chemical tests, cell counts and culture though, depending on the exact volume submitted, the laboratory cannot guarantee the ability to perform every ordered test. Tests ordered for which there is not enough CSF to perform the test will be resulted as “quantity not sufficient for analysis” (QNS). In addition, submitting fewer than four tubes will necessitate that a single sample be shared among multiple laboratory departments which may increase the result turnaround time.

If a less than ideal volume of CSF is submitted you may wish to indicate which tests are a priority for your patient (i.e. “please perform cell count first”) and the laboratory will direct the sample accordingly.

Orders received without tube number specification will be ordered by the laboratory as described below:

Default tube numbers for type of testing
Number of tubes submitted 4 tubes 3 tubes 2 tubes* 1 tube*
Chemistry (glucose, lactate, LDH, protein, etc) 3 3 1 1
Cultures (bacterial, viral) 2 2 2 1
Cell Count (appearance, color, RBC, nucleated cells) 1 and 4 1 and 3 2 1
Other (oligoclonal banding, VDRL, etc. 4 1 1 1

*It is inadvisable to submit one or two tubes only if more are possible. Indicate order of preference for tests requested.

Client services provided by the clinical laboratory

The Clinical Laboratory at University of Colorado Hospital offers its services to internal and external customers for all tests it performs.

The laboratories at University of Colorado Hospital and the University of Colorado Denver are uniquely qualified to offer the services of their sophisticated laboratories and expert scientific, doctoral and medical staff to provide state-of-the-art testing procedures and diagnostic interpretive consultations.

Client services such as monthly billing, multiple chart or result reporting and 24-hour therapeutic drug monitoring are available.

To arrange to use the services provided by the laboratories of University of Colorado Hospital and the University of Colorado Denver, call Clinical Laboratory Client Services at 720-848-4401.

Client services specimen packaging and transport

To ensure optimum testing conditions for a specimen that is sent to University of Colorado Hospital Reference Laboratory, the client must determine two things:

  1. Determine the nature of the specimen to be sent, using the definitions below.
  2. Determine the temperature at which the specimen must be maintained during transport, using instructions for individual tests listed in the Test Catalog.

Ship to:

University of Colorado Hospital – Clinical Lab
12401 E. 17th Avenue, Room 253
Aurora, CO 80045

Nature of Specimen to be Transported

Exempt Human Specimens: A clinical specimen (blood, secreta, tissue, tissue fluid) known to contain a Risk Group I agent or not known to contain, or suspected to contain, a pathogen from Risk Group II, III, IV or a Biological Substance, Category B in which the pathogen has been neutralized or inactivated to it cannot cause a disease when exposure to it occurs.

Biological Substances, Category B: Any human or animal material, including excreta, secreta, blood and its components, tissue and tissue fluids, being transported for diagnostic or investigational purposes, but excluding live infected humans or animals. Note: specimens known to originate from patients with a Risk Group II or II pathogen should be shipped as Biological Substances.

The following Biological Substance Shipping Guidelines (IATA Packing Instructions 650) are to be utilized.

  1. A watertight primary receptacle.
  2. A watertight secondary receptacle.
  3. An absorbent material placed between the primary receptacle and the secondary receptacle.
  4. A sturdy outside packaging constructed of corrugated fiberboard, wood, metal or plastic.

Specimen from Patient with Known or Suspected Creutzfeldt-Jakob or Other Prion Disease:

  1. Labeling: Specimens must be CLEARLY AND PROMINENTLY labeled as to the potential hazard. The specimen container and the request form must be labeled with the hazard warning “R/O CJD” or “R/O Prion Disease”.
  2. Packaging: Follow the guidelines above for packaging of Biological Substances adding EXTRA PRECAUTIONS.
  3. EXTRA PRECAUTIONS require that the specimen is placed in a tertiary container that is able to withstand rough handling. A 95 kPa bag or container is recommended. If one is not available, a screw-top container or extra padding is acceptable.
  4. Transport: Use shipping containers specifically manufactured for packaging and transport of biological substances.
  5. Rejection of Specimens: In the interest of safety, specimens that have been improperly labeled, packaged, or transported may be rejected.

Frozen (Dry Ice) Shipments: A minimum of 2 lbs (1kg) of dry ice should be used depending on weather conditions. Be aware that dry ice is a dangerous good and must always be declared by marking, labeling and documentation. If there are no other dangerous goods in a shipment with dry ice, a formal Shipper’s Declaration is not required. Refer to IATA packing instruction 904.

Note: Each laboratory is responsible for implementing procedures that comply with the regulations set forth by the DOT and the International Air Transport Association (IATA).

All client specimen transportation will be managed according to the established procedure between the client and the Clinical Laboratory at University of Colorado Hospital.

Instructions for microbiology specimen collection

The usefulness of culture result information is directly proportional to the quality of the specimen provided to the laboratory.

General Guidelines

  • Collect specimen before antibiotic therapy. If this is not possible, specify antibiotic in the request.
  • Notation of diagnosis, foreign travel, animal contact, immunosuppressive disease, or suspected organism is helpful.
  • First morning specimens are usually preferred, especially if urine or sputum specimens for TB.
  • Avoid contamination of the sample with normal flora by decontaminating surface area prior to collecting the specimen. Contamination can usually be evaluated by the number of epithelial cells seen on gram stain examination. It is preferable to obtain specimens bypassing normal flora whenever possible. For urines, single catheterized specimens are cleaner than midstream clean catch specimens. Deep wounds collected by aspiration are preferable to superficial swab collection. For sputum specimens, having the patient rinse their mouth before expectorating may reduce oral-pharyngeal contamination.
  • Do not allow swabs to dry out. Follow instructions for proper use of specimen collection devices provided with each unit. Use no fixatives or bacteriostatic agents for cultures. View guidelines for choosing the correct swab or container for the test.
  • For hospital patients and on-site clinics, deliver to laboratory within 2 hours, sooner if possible. Deliver immediately if results are needed STAT. Urine can be refrigerated if delivery is delayed. Rapid delivery is especially important for CSF specimens, stools for O & P examination, Neisseria cultures, and anaerobic specimens.
  • For off-site clinics or doctors’ practices, various transport systems are available. Please contact the laboratory for provision of required transport tubes or, if necessary, STAT pickup. Note: Due to the instability of Neisseria gonorrheae, specimens for GC culture from off-site clinics should be collected in transport media.
  • Call the laboratory before collection of specimens for malaria so processing can begin immediately upon receipt.
  • Anaerobic transport media is available from Supply Chain. Anaerobic transport media is usually not necessary if the specimen is delivered to the laboratory immediately.
  • Whenever submitting body fluid for culture, send the fluid in a sterile container specifically for microbiology. Do not inoculate blood culture media except for peritoneal fluid and also send uninoculated fluid in a sterile container.
  • Positive culture plates are held for seven days in the event that non-routine antimicrobial susceptibility testing is requested.

Procedures for Obtaining Blood Cultures

See Lippincott Procedure Blood Culture Sample Collection and Blood Culture Job Aid.

Rapid Strep Throat Swab Collection

Rapid Strep Sample Requirements

Stat Gram Stain

STAT Gram stains on cerebrospinal and other body fluids are available 24 hours per day.

Laboratory computer system

Order Entry and Result Inquiry

The Epic Information System is used to order laboratory tests and view results.

Computer Downtime

“Downtime” is defined as that time when the computer system is unavailable for routine use by the regular users.

  • Scheduled Downtime: Downtime may be scheduled, that is, previously announced for short periods of time. This occurs periodically for routine preventive maintenance, reprogramming procedures and back-up of the system. During these scheduled downtimes, all Critical results are called to the unit/clinic and results are entered into the computer as soon as it is available.
  • Unscheduled Downtime: Downtime may occur inadvertently due to equipment malfunction or power surges, glitches or outages. This may be temporary, lasting as little as a few minutes or more severe, lasting hours.  Depending on the length of the downtime and the anticipated time to start up, critical values will be called and STAT results will be faxed, tubed, or hand-delivered to the ordering unit until computer operations are restored.
Nasal Wash and Swab Collection

NASOPHARYNGEAL SWAB COLLECTION

nasal wash and swab collection

MATERIALS NEEDED:

  • Flocked tipped nasopharyngeal swab with nylon fiber and aluminum shaft (Lawson# 63252).
  • DO NOT USE wood-shafted or calcium alginate swabs.
  • M6 Viral Transport Media (Lawson# 64758).

PROCEDURE

  1. Put on a fresh pair of non-sterile exam gloves.
  2. Gently insert swab into a nostril straight back (not upwards), along the floor of the nasal passage until reaching the posterior wall of the nasopharynx. The distance from the nose to the ear gives an estimate of the distance the swab should be inserted.Note: Do not force swab – if an obstruction is encountered, try the other nostril.
  3. Leave swab in place for up to 10 seconds.
  4. Remove swab slowly.
  5. Bend handle of swab 1.5 to 2 inches straight down towards swab tip. Immediately place swab into the M4 Transport media. Leave swab in transport media. Swab should be entirely enclosed in tube, no wire should extend past lip of tube. Replace lid to transport media, tighten to prevent leakage during transport.
  6. Label the specimen, place in biohazard bag with completed requisition, and send to laboratory. Transport same day, refrigerated or on ice. If delivery is not expected within 24 hours, freeze at -70 degrees C and ship on dry ice.

Tip: If patient is seated for the procedure, have patient sit with head against a wall as patients have a tendency to pull away during the procedure.

NASOPHARYNGEAL WASH WITHOUT MECHANICAL SUCTION

PROF-Nasal-Wash-no-suction-1.JPG

GOAL: Collect ciliated columnar respiratory epithelial cells from posterior nasopharynx for virus tests

MATERIALS NEEDED:

  • Personal protective equipment
  • Facial tissue
  • Sterile nonbacteriostatic saline (eg. bullets)
  • Sealable biohazard bags
  • Closable sterile specimen container (eg. sterile urine cup)
  • Shipping container with cold pack (off-site clinics or outside clients)
  • Syringe method:
  • 3-5 ml sterile disposable syringe
  • Sterile soft catheter (eg. #8 soft French feeding tube). Base syringe size and tubing length on age and size of patient.
  • Bulb method: 1-2 oz tapered tip sterile rubber bulb

COLLECTION METHOD

NOTE: Use two care providers for this technique if possible, one to hold the patient and the other to collect specimen.

PROF-Nasal-Wash-no-suction-2.JPG

  1. Don PPE. Wipe excess mucus from patient’s nose with facial tissue.
  2. Fill syringe with 1-4 ml saline. Amount depends on size and age of patient. Attach tubing to syringe tip.
  3. Tilt patient’s head back slightly beyond “sniff position.” Instruct older patients not to swallow.
  4. Instill saline into one nostril while holding second nostril closed.
  5. Aspirate fluid gently while withdrawing and rotating tube to dislodge cells and secretions.NOTE: Recovery must occur rapidly or instilled fluid will rapidly drain down the throat.
  6. Inject specimen into the container. Repeat with other nostril and inject specimen into same container.
  7. Label container and place in biohazard bag. Discard syringes and tubing or bulb in biohazard waste.
  8. Tube specimen immediately to lab or send on wet ice.

NASOPHARYNGEAL WASH WITH MECHANICAL SUCTION

specimen collection and handling

GOAL: Collect ciliated columnar respiratory epithelial cells from posterior nasopharynx for virus tests

MATERIALS NEEDED:

  • Personal protective equipment
  • Facial tissue
  • Sterile nonbacteriostatic saline (e.g. bullets)
  • Suction pump or wall suction
  • Delee suction trap with attached suction catheter
  • Patient Age Catheter size Suction pressure
    • Premature 6 80-100 mm Hg
    • Infant/Toddler 8 80-100 mm Hg
    • School Age 10 100-120 mm Hg
  • Sealable biohazard bags
  • Shipping container with cold pack (outside clients)

nasal wash and swab collection

COLLECTION METHOD

NOTE: Use two care providers for this technique if possible, one to hold the patient and the other to collect specimen.

  • Don PPE. Remove excess mucus from patient’s nose with facial tissue.
  • Determine length of suction catheter by measuring distance from tip of nose to external ear opening. Mark with thumb and forefinger.
  • Attach trap to suction tubing, leaving wrapper on suction catheter. Adjust suction to appropriate pressure.
  • Tilt patient’s head back slightly beyond “sniff position.” Instruct older patients not to swallow.
  • Add 0.5-4 ml saline to nostril (amount depends on patient’s size) to loosen secretions and dislodge cells.
  • Gently insert tube into nostril and posterior pharynx until the thumb and forefinger touch the patient’s nose. NOTE: Don’t use lubricants other than saline to aid tube insertion.
  • Apply suction while withdrawing and rotating tube. Hold trap upright to prevent loss of secretions from trap. NOTE: Catheter should remain in nasopharynx no longer than 10 seconds
  • Repeat procedure for second nostril.
  • Disconnect suction. Remove cap with tubing and place in biohazard waste.
  • Place new cap on trap. Label trap and place in biohazard bag.
  • Tube specimen immediately to lab or send on wet ice.

Artwork and instructions provided by BECTON DICKINSON & CO., Cockeysville, MD Rev 03/30/05

Packaging and transporting specimens to the laboratory – inpatients and outpatients

All specimens must be handled according to procedures and policies established for standard precautions at the University of Colorado Hospital.

Packaging

Refer to the “Specimen Acceptability and Transport” policy in the UCHealth/Source Policies & Procedures web directory for detailed instructions.

The primary container for all specimens must be leak-proof and must contain the patient’s name and medical record number. Ensure that lids of containers are secure.

Each specimen must be placed inside a secondary container for transport. The secondary container is a securely sealed zip lock plastic bag labeled with the biohazard symbol pictured below.

Exception: Blood, blood components, or blood products that are labeled as to their contents and have been released for transfusion or other clinical use are exempted from this requirement.

Plastic bags with the biohazard symbol are obtained from Supply Chain (item number 10897.

Limit contents to one patient’s samples per bag.

Paper lab requests, if used, should be placed in the external sleeve of the bag or attached to the outside of the bag.

The laboratory will not accept or process specimens with exposed needles or sheathed needles attached.

Click here for special instructions for labeling, packaging and transport of specimens from patients with known or suspected CJD or another prion disease.

Transport

Refer to the “Specimen Acceptability and Transport” policy in the UCHealth/Source Policies & Procedures web directory for detailed instructions.

Specimens may be delivered to the laboratory by:

I. The pneumatic tube system

  • USE SPECIALLY PADDED CARRIERS ONLY.
  • DO NOT OVERLOAD.
  • ENSURE THAT SPECIMEN CONTAINERS AND TRANSPORT BAGS ARE SECURELY SEALED. DOUBLE-BAG URINE SPECIMEN CONTAINERS.
  • ENSURE THAT THE LATCH ON THE CARRIER IS SECURELY CLOSED.
  • DO NOT USE THE TUBE SYSTEM FOR SPECIMENS FROM PATIENTS WITH KNOWN OR SUSPECTED CREUTZFELDT-JAKOB OR OTHER PRION DISEASE.

II. Delivering directly to the laboratory

  • Leprino Building (LB), room 253
  • AIP Room 2.500.A for Transfusion Service specimens only

III. Calling transport

If using the pneumatic tube system to transport blood cultures, place green top in separate plastic bag toward the “necks” of the bottles. DO NOT SEND MORE THAN ONE BLOOD CULTURE SET PER CARRIER.

For problems with the pneumatic tube system, please call Engineering Services.

Specimen collection and processing procedures

Proper specimen collection and handling is an integral part of obtaining a valid and timely laboratory test result. Specimens must be obtained in the proper tubes or containers, correctly labeled, and then promptly transported to the laboratory. Obtaining reliable and accurate laboratory test results

Physicians and others responsible for obtaining specimens and transporting them to the laboratory have a vital role in ensuring that laboratory test results are valid. The following are essential safeguards for your patients.

1. Avoid patient identification errors.  Use at least two patient identifiers when collecting blood samples and other specimens for clinical testing. See Specimen Labeling section of this web page.

2. Draw the tubes in the proper sequence

When multiple tubes are to be drawn from a single venipuncture using an evacuated tube system (e.g. BD Vacutainer® or Greiner Vacuette®), there is a correct sequence for blood collection that prevents cross-contamination of tube additives that could cause erroneous test results.

The order of draw

  1. Blood culture
  2. Coagulation tube (blue top)*
  3. Serum tube with or without clot activator, with or without gel (red or gold top)
  4. Heparin tube with or without gel plasma separator (green top)
  5. EDTA (purple top, pink top)
  6. Oxalate and fluoride (gray top)
  7. Other special tubes

* All blue tops collected for coagulation assays which do not have a blood culture collected first must have a discard tube collected prior to filling. Discard tube should be another blue top in which greater than 1 mL of blood is collected.

All tubes must be gently inverted 10 times end-to-end immediately after collection.

3. Use proper containers for collection

Certain analyses require containers with preservatives and/or anticoagulants, while others do not. Using the wrong container often leads to erroneous results. See the test catalog for exact requirements.

4. Mix all tubes ten times by gentle inversion immediately after collection

5. Do not decant specimens from one type of container into another.  Specimens must be submitted to the laboratory in the container used originally for collection.

6. Deliver specimens to the laboratory promptly.  See Test Catalog for storage and transport requirements.

Laboratory specimen storage temperatures:

Refrigerated: 2 – 8 º C

Frozen: less than or equal to -20 º C

Room/ Ambient: 20 – 25 º C

7. Avoid hemolysis

Erythrocytes contain certain analytes (LD, AST, K, ALT) in concentration many times higher than in plasma. When red cells are hemolyzed, there is a release of these analytes and dilution of plasma, resulting in erroneous laboratory values.

8. Drawing samples from a line

If the sample is to be drawn from a line, be sure to draw approximately 5-10 mL for adults in a first “flush” syringe (20 mL to clear any heparin from the line if coagulation tests are desired). Then draw the syringe for the desired tests. The “flush” may be given back to the patient if needed.

Stat test turnaround times

The laboratory provides STAT testing for the tests listed here.  Time is measured from receipt of the specimen in the laboratory to release of results.

STAT Turnaround Time in Minutes (unless otherwise specified)
ABO/Rh 30
ABO/RH for RhoGam 60
Amikacin 45
Antithrombin III Activity 60
Arterial Blood Gases and Co-oximetry 10
Bacterial Vaginosis Gram Stain 60
Basic Metabolic Panel:
Electrolytes, BUN, Creatinine, Glucose
45
Beta HCG, Quantitative 60
Caffeine 120
Calcium, ionized 10
CBC (Complete Blood Count) 30
CKMB 60
D-dimer 35
Drug Screen, Abuse (for qualitative screening – confirmations sent out) 60
Drug Screen, Urine (for qualitative screening – confirmations sent out) 60
Ethylene Glycol 120
Factor Activities 120
Fetal Fibronectin 60
Fibrinogen 35
Flu Test (INFLUENZA A/B PCR) 240
Glucose, Whole Blood 10
Gram Stain 60
Heparin Level 60
Heparin Level, Low Molecular Weight Heparin 60
Lidocaine 4 – 5 hours
Lithium 60
Methotrexate 120
Mono Test (Heterophile) 60
Occult Blood (Emergency Department Only) 60
Pregnancy Test 30
PT (Prothrombin time) 35
PTT (Activated Partial Thromboplastin Time) 35
Strep Test, Rapid 60
Troponin I 45
Type and Screen 60
Urinalysis 35
Specimen labeling

Refer to UCHealth Specimen Labeling policy in the Source.

Proper specimen labeling is required to protect patients from adverse consequences of errors due to improper labeling and to meet laboratory accreditation requirements. Always label specimens while still in the presence of the patient/at the bedside.The following policy for unacceptably labeled specimens will be enforced:

  1. A specimen will be considered unacceptably labeled if the container holding the specimen (test tube, urine container, specimen jar, swab, etc.) does not have the patient’s last and first name and medical record number or birth date.
  2. Note: The specimen container itself must be properly labeled. If a specimen is placed in a plastic bag, it is not adequate to place a label on the bag rather than on the tube. Whenever the specimen itself is not labeled, the label will be considered unacceptable.
  3. The specimen will be considered unacceptably labeled if the specimen arrives in the laboratory where the name on the specimen differs from the name on the requisition or extra labels, or if more than one patient’s specimens are contained in one bag.
  4. If the unacceptably labeled specimen is one that can be reobtained by venipuncture or recollection (e.g. urine sample) the unit will be notified that a new specimen is required.
  5. If the unacceptably labeled specimen is one that cannot be re-obtained (CSF, body fluids such as peritoneal or synovial fluid, bone marrow, stones, operative specimens, catheter tips, special procedural collections [e.g. bronchoalveolar lavages], or non-line arterial blood gases), the person who originally collected the specimen must acknowledge the identity of the specimen in writing.
  6. All specimens for the Blood Bank require a new specimen on any unacceptably labeled specimen. There are no exceptions. Click here to view UCHealth “Blood Administration” policy.
  7. Proper placement of barcoded labels is essential for all 5 and 7 mL blood specimen tubes. Labels must be straight, wrinkle-free, and oriented as follows:

specimen collection and handling

Stool collection guide

Click here to view instructions for collecting stool for PCR, C. difficele, ova and parasites, and occult blood.

FECAL OCCULT BLOOD (FOB)

The following collection containers for FOB specimens must be obtained from Supply Chain.

  • Collection Container: Polymedco Collection Device (Lawson #19753)
  • Patient Pack: Polymedco Collection Device with collection instructions and mailing envelope (Lawson #53544)

Collection Instructions (Polymedco collection devices MUST be used as follows):

  1. Open cap by twisting and lifting.
  2. Scrape the surface of the fecal sample with the sampling probe, completely covering the grooved portion.
  3. Close sampling bottle by inserting the sampling probe and snap green cap on tightly, do not reopen.
  4. Label with the barcoded patient label as shown, or, if no barcoded labels are available, label with patient’s last name, first name and medical record number or date of birth. Refer to “Specimen Labeling” section of this document.
  5. Send the inoculated Polymedco collection device to the lab.

 

Urine collection

Urinalysis

Click here for more information about Urine Collection Systems.

Urine specimens for urinalysis must be tested within 2 hours of specimen collection. Prompt transport of fresh specimens is expected. If unable to transport within this guideline, the specimen must be refrigerated until delivery. 24-hour specimens are unacceptable for urinalysis testing.

Clean Catch for Culture

  • Wash with soap and rinse external genitalia. Catch midstream specimen in a sterile urine container.
  • Must be refrigerated if not plated within 2 hours.
  • No 24-hour specimens.
  • If antibiotic therapy is noted on the requisition, the lab will process with longer incubation.

Urine Collection 2, 12 or 24 Hours and Timed Specimens

Container

24-Hour urine collection containers may be obtained from Supply Chain. The laboratory does not supply collection containers.

Preservatives

Some tests or collection procedures require additives to the timed urine container. Please refer to the individual test listings for details of preservative requirements.

Patient Preparation

Adequately pre-hydrate the patient to assure good urine flow. Dietary restrictions are required for some procedures and are specified in the individual test listings.

Procedure

  1. Have the patient void, completely emptying the bladder.
  2. Discard this specimen.
  3. Start the collection timing at this point and write the start time and date on the bottle.
  4. For the next 24 hours (or required time), save all urine voided by adding to the collection container.
  5. Exactly 24 hours (or required time) from the starting time, have the patient void, completely emptying the bladder. Add this specimen to the collection container. Write this time and date on the bottle.
  6. Stop the collection and label the specimen, and request slip if used, with name and medical record number. Indicate collection start date and time and stop date and time in the request.

Since results are based on the total volume, it is critical that the total volume collected be submitted. The laboratory will measure and report the total volume on all timed urines. Alternatively, it is acceptable to submit an aliquot of a well-mixed, accurately measured urine specimen. The total volume must then be included in the request.