Specimen Handling in Phlebotomy
Proper specimen handling is critical to ensuring accurate laboratory test results. From the moment blood is drawn to when it reaches the laboratory, every step in the preanalytical phase affects specimen quality and patient safety. This comprehensive guide covers labeling requirements, processing protocols, transport conditions, and certification exam essentials for phlebotomy specimen handling.
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The Preanalytical Phase
The preanalytical phase encompasses all steps that occur before laboratory analysis: test ordering, patient preparation, specimen collection, labeling, handling, processing, and transport. Studies show that 70-80% of all laboratory errors occur during the preanalytical phase, making proper specimen handling critical for patient safety and quality care.
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
Specimen Labeling Requirements
Proper specimen labeling is a critical patient safety practice that prevents misidentification errors. Every specimen must be labeled at the patient's bedside immediately after collection, before leaving the patient's presence. Never pre-label tubes or label specimens away from the patient.
Required Label Elements
Every specimen label must include these minimum elements for proper identification:
- 1.Patient's full name (first and last, exactly as it appears in the medical record)
- 2.Patient's unique identification number (medical record number, account number, or date of birth)
- 3.Date of collection (month/day/year)
- 4.Time of collection (using 24-hour military time or clearly marked AM/PM)
- 5.Phlebotomist's initials or identification (for accountability and follow-up questions)
Critical Safety Rule
Labels must be applied to the tube itself, not to the cap. Caps can be removed or switched, leading to patient misidentification.
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.
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Specimen Processing Requirements
Different specimen types require different processing steps to ensure accurate test results. Understanding these requirements is essential for phlebotomy practice and certification exams.
Serum Specimens (Red Top, SST/Gold Top)
Serum is obtained by allowing blood to clot and then centrifuging to separate the liquid serum from the clot. Serum specimens are used for chemistry tests like CMP, BMP, liver function tests, and many hormone assays.
Processing Steps:
- 1. Allow blood to clot completely (typically 30-60 minutes at room temperature)
- 2. Do not refrigerate during clotting period (cold can inhibit clotting)
- 3. Centrifuge at appropriate speed and time per manufacturer instructions
- 4. Separate serum from clot into a labeled transfer tube if required
- 5. SST tubes contain gel that forms a barrier between serum and clot after centrifugation
Plasma Specimens (Lavender, Light Blue, Green Top)
Plasma is obtained by collecting blood in tubes containing anticoagulants, mixing immediately, and centrifuging without allowing blood to clot. Plasma specimens are used for CBC (EDTA), coagulation studies (citrate), and some chemistry tests (heparin).
Processing Steps:
- 1. Gently invert tube immediately after collection (5-10 times) to mix anticoagulant
- 2. Can be centrifuged immediately — no clotting time needed
- 3. For coagulation studies, centrifuge within specified timeframe (typically 1-2 hours)
- 4. Some tests require platelet-poor plasma (double-spin centrifugation)
Whole Blood Specimens
Some tests require whole blood with no separation. Examples include CBC, blood bank typing and crossmatch, lead levels, and HbA1c. These specimens are mixed but not centrifuged.
Processing Steps:
- 1. Gently invert tube immediately after collection to mix anticoagulant
- 2. Store according to test requirements (usually refrigerated for blood bank, room temp for CBC)
- 3. Do not centrifuge — keep cells suspended
Specimen Transport and Storage
Proper transport and storage conditions are essential to maintain specimen integrity. Temperature, time delays, and protection from light all affect test results.
Temperature Requirements
Room Temperature (15-25°C/59-77°F)
Blood cultures, cold agglutinins, cryoglobulins, serum tubes during clotting period, potassium (to prevent falsely elevated levels from cold), PTT/PT during transport.
Refrigerated (2-8°C/36-46°F)
CBC, most chemistry tests after processing, blood bank specimens, most urine specimens, ammonia (on ice), lactic acid (on ice).
Frozen (-20°C/-4°F or colder)
Certain specialized tests like genetic studies, some viral titers, and hormone assays (check specific test requirements).
Body Temperature (37°C/98.6°F)
Cold agglutinins — must be kept warm from collection through processing to prevent false-positive results.
Light-Sensitive Tests
Certain analytes are photosensitive and degrade when exposed to light. These specimens must be protected from light during transport and storage by wrapping tubes in aluminum foil or placing them in amber-colored transport bags.
Common light-sensitive tests:
- Bilirubin (can decrease by 50% in 1 hour under bright light)
- Vitamin B12 and folate
- Porphyrins
- 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: Process and deliver immediately (within 15 minutes)
- Ammonia: On ice, process within 15-30 minutes (very unstable)
- Lactic acid: On ice, process within 15 minutes
- PTT/PT for coagulation: Process within 1-2 hours
- Blood cultures: Deliver to lab immediately for prompt incubation
- CBC: Analyze within 4 hours for accurate platelet counts
Specimen Rejection Criteria
Laboratories have specific criteria for rejecting specimens that do not meet quality standards. Rejected specimens must be recollected, causing patient discomfort, delays in diagnosis, and increased costs. Understanding rejection criteria helps you prevent these issues.
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 Specimens
Chain of custody refers to the documentation that tracks the handling of specimens that may be used as legal evidence, such as blood alcohol levels, drug screens for employment or legal proceedings, and forensic specimens. These specimens require special handling and documentation to ensure legal admissibility.
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
Legal Implications
Any break in the chain of custody can render the specimen inadmissible in legal proceedings. If you are collecting specimens for legal or employment purposes, follow your facility's specific chain of custody protocols exactly. Never deviate from established procedures.
Specimen Handling on Certification Exams
Specimen handling is a major focus area on all phlebotomy certification exams. You can expect multiple questions covering these topics:
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
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Clinical References
- CLSI H3-A6 — Procedures for the Collection of Diagnostic Blood Specimens by Venipuncture
- CLSI GP41 — Collection of Diagnostic Venous Blood Specimens
- NHA CPT Exam Content Outline (2024)
- ASCP Board of Certification Content Guidelines
- OSHA Bloodborne Pathogens Standard (29 CFR 1910.1030)
- CDC Guidelines for Infection Control in Healthcare Settings
Related Study Topics
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Proper labeling, transport requirements, processing timelines, and rejection criteria.
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