Specimen Handling in Phlebotomy

What time format should you use when labeling a phlebotomy specimen?

Most facilities and certification exams expect 24-hour (military) time, which runs from 0000 (midnight) to 2359 with no AM or PM. Before noon, write the hour with a leading zero: 9:05 AM is 0905. After noon, add 12 to the hour: 1:30 PM is 1330 and 11:45 PM is 2345. Military time removes AM/PM mix-ups on time-sensitive specimens such as timed draws and drug levels.

Required label elements

When should a blood specimen be labeled?

Label every tube immediately after collection, at the bedside and in the presence of the patient, before you leave the room. Never pre-label tubes or carry unlabeled tubes out of the room to label later. The Joint Commission requires specimen containers to be labeled in the presence of the patient (NPG.01.01.01, formerly NPSG.01.01.01), because labeling away from the patient makes it possible to put one patient's label on another patient's blood.

Patient identification guide

What is the best practice for reducing specimen misidentification during send-out testing?

Apply barcoded labels at the bedside or collection site, in the patient's presence, right after the draw. Labeling tubes later before shipping, handwriting labels without patient identifiers, or relying on courier logs all leave a gap in which specimens can be switched. A barcode that carries at least two patient identifiers lets the reference laboratory match the specimen to the patient electronically.

Barcode labeling systems

Which specimens must be protected from light?

Bilirubin is the classic light-sensitive specimen; others include beta-carotene, vitamin A, vitamin B6, vitamin B12, folate and porphyrins. Light breaks these analytes down, so results can be falsely low if the tube sits exposed on a counter or under a phototherapy (bili) light. On exams, special handling for a bilirubin test means protecting the specimen from light.

Light-sensitive tests

How should light-sensitive samples be prepared for transport?

Collect them in an amber light-blocking tube, or wrap the labeled tube in aluminum foil immediately after collection, and keep it shielded through transport, processing and storage. Any serum or plasma poured off later goes into an amber transport tube. ARUP, for example, tells collectors to protect bilirubin specimens from light during collection, storage and shipment and to send them in an amber transport tube.

Light-sensitive tests

How do you chill a blood specimen during transport?

Place the tube in an ice-water slurry (crushed ice mixed with water) immediately after collection. The slurry surrounds the tube for fast, even cooling, while large ice cubes leave gaps and give poor contact with the tube. Deliver chilled specimens to the lab right away, because most of them also have short processing limits.

Temperature requirements

Which tests require a chilled specimen?

Ammonia, lactic acid (lactate) and ACTH are common tests that are chilled immediately after collection; your lab's collection manual lists any others. Chilling slows cell metabolism, which would otherwise raise ammonia and lactate or break down ACTH in the tube. Labcorp, for example, requires ammonia specimens to be placed on ice immediately and the plasma separated within 15 minutes of collection.

Ammonia tube and handling

What temperature errors cause a specimen to be rejected?

Common temperature rejections are a specimen that should have been chilled but arrived warm (such as ammonia not kept on ice), a coagulation specimen that was refrigerated, and a cryoglobulin or cold agglutinin specimen that cooled below body temperature before the serum was separated. A specimen held outside its required temperature no longer reflects the patient's blood. Mayo Clinic Laboratories, for example, requires cryoglobulin specimens to stay at 37°C until the serum is separated from the cells.

Specimen rejection criteria

When must an anticoagulated specimen be centrifuged?

An anticoagulated (plasma) tube needs no clotting time, so it can be centrifuged as soon as it reaches processing, and the plasma should be separated from the cells within 2 hours of collection unless the test sets a shorter limit. Some tests are much stricter: ammonia and lactate plasma is separated within about 15 minutes, and coagulation specimens from patients on unfractionated heparin within 1 hour. Cells left in contact with plasma keep metabolizing and leaking their contents, which changes the results.

Plasma processing steps

How long can serum stay on the cells before it is separated?

No more than 2 hours from collection, and less for some tests (ARUP asks for 30 minutes for its comprehensive metabolic panel). Let the serum tube clot completely at room temperature, centrifuge it, and separate the serum from the cells within that window. Left on the cells, glucose falls as the cells consume it and potassium leaks out of the cells into the serum.

Serum processing steps

How should you prepare blood specimens for shipping to an out-of-area laboratory?

Follow the receiving laboratory's requirements: centrifuge and separate serum or plasma within 2 hours of collection, transfer it to a labeled transport tube, and ship it at the required temperature (room temperature, refrigerated or frozen). Do not send unspun tubes unless the testing lab will centrifuge and separate them within 2 hours of collection. Diagnostic specimens ship in leak-proof triple packaging marked UN3373 (Biological Substance, Category B).

Transport and storage

How does hemoconcentration affect a blood specimen?

Hemoconcentration falsely raises cell counts and large molecules such as proteins and protein-bound analytes. It happens when plasma water filters out of the vein while cells and large molecules stay behind, most often because the tourniquet was left on longer than 1 minute or the patient pumped their fist. Releasing the tourniquet within 1 minute prevents it.

Tourniquet use guide

Why Specimen Handling Matters

Improper specimen handling can lead to inaccurate test results, misdiagnosis, incorrect treatment, unnecessary repeat draws (causing patient discomfort and increased costs), and delayed care. As a phlebotomist, you are the first line of defense in ensuring specimen integrity.

• Hemolysis (rupture of red blood cells) can falsely elevate potassium, LDH, and AST results
• Delayed processing can cause glucose levels to drop and potassium to rise
• Improper mixing can lead to clotted specimens or inadequate anticoagulation
• Incorrect labeling can lead to life-threatening patient misidentification errors

Required Label Elements

Every specimen label must include these minimum elements for proper identification:

1. 1.Patient's full name (first and last, exactly as it appears in the medical record)
2. 2.Patient's unique identification number (medical record number, account number, or date of birth)
3. 3.Date of collection (month/day/year)
4. 4.Time of collection (using 24-hour military time or clearly marked AM/PM)
5. 5.Phlebotomist's initials or identification (for accountability and follow-up questions)

Barcode Labeling Systems

Most healthcare facilities use barcode systems for specimen labeling. The phlebotomist scans the patient's wristband or requisition, and the system generates labels with all required information. This reduces transcription errors and improves efficiency. However, you must still verify that the printed information matches the patient's verbal identification and wristband.

Handling Unlabeled or Mislabeled Specimens

If a specimen arrives in the laboratory without a label or with incomplete/incorrect information, it must be rejected. The laboratory cannot process unlabeled specimens due to patient safety risks. A new specimen must be collected. Some facilities have specific policies for relabeling specimens in the laboratory with witnessed identification, but this varies by institution and should only be done according to strict protocols.

Temperature Requirements

Light-Sensitive Tests

Certain analytes are photosensitive and degrade when exposed to light. Collect them in an amber light-blocking tube, or wrap the tube in aluminum foil (or place it in a light-tight container) immediately after collection, and keep it protected through transport, processing and storage.

Common light-sensitive tests:

• Bilirubin (the light-sensitive test most often asked about on exams)
• Vitamins A, B6 and B12, and folate
• Porphyrins
• Beta-carotene
• Some vitamins and medications

Time-Critical Specimens

Some tests must be processed or delivered to the laboratory within strict time limits to ensure accurate results:

• STAT specimens: Deliver and process immediately, within your facility's turnaround target
• Ammonia: On ice immediately; separate plasma within 15 minutes (very unstable)
• Lactic acid: On ice, process within 15 minutes
• PT/PTT for coagulation: Keep at room temperature and test within the lab's limit; centrifuge within 1 hour for patients on unfractionated heparin
• Blood cultures: Deliver to lab immediately for prompt incubation
• Serum and plasma: Separate from cells within 2 hours of collection unless the test requires sooner

Unlabeled or Mislabeled Specimens

Missing patient name, ID number, date, time, or phlebotomist initials. Label on cap only instead of tube.

Hemolyzed Specimens

Pink or red serum/plasma indicating ruptured RBCs. Cannot be used for potassium, LDH, AST, magnesium, and many other tests.

Clotted Specimens

Anticoagulated tubes (lavender, light blue, green) that contain clots due to inadequate mixing or delayed mixing.

QNS (Quantity Not Sufficient)

Insufficient blood volume to perform the ordered test(s). Particularly critical for light blue top coagulation tubes (must be filled to proper level for correct blood-to-anticoagulant ratio).

Incorrect Tube Type

Wrong anticoagulant or additive for the test ordered. For example, collecting CBC in red top instead of lavender, or chemistry in lavender instead of gold/red.

Lipemic Specimens

Cloudy, milky appearance due to high lipid content. May interfere with certain chemistry tests. Often patient preparation issue (not fasting).

Contaminated Specimens

Drawn from IV line or above IV site, causing dilution and false results. Collected from same arm as mastectomy (lymphedema risk).

Expired Collection Tubes

Tubes used past expiration date. Vacuum may be lost, anticoagulants may be degraded.

Chain of Custody Requirements

• Patient must be positively identified with photo ID when possible
• Patient (or witness) must observe the entire collection process
• Specimens must be sealed with tamper-evident tape immediately after collection
• Documentation form must record every person who handles the specimen with date, time, and signature
• Specimens must be stored securely (locked) when not being actively transported or tested
• Patient and collector must sign and date chain of custody form at time of collection

High-Yield Exam Topics

• Required elements on specimen labels (when and where to label)
• Processing differences between serum and plasma specimens
• Proper storage temperatures for specific test types
• Light-sensitive tests (bilirubin is most commonly tested)
• Time-critical specimens (ammonia, lactic acid)
• Causes of hemolysis and which tests are affected
• Specimen rejection criteria (QNS, clotted, unlabeled)
• Chain of custody procedures for legal specimens