Vacuum blood collection tubes are essential tools in medical and
laboratory settings for collecting blood samples efficiently and safely.
These tubes are pre-evacuated, creating a vacuum that automatically
draws a specific blood volume into the tube when a needle is inserted
into a patient’s vein.
Key Components:
Tube: Made of glass or plastic, the tube is
pre-filled with a vacuum that determines the amount of blood drawn.
Cap: The cap is color-coded based on the type of
additive inside the tube, indicating its use (e.g., for serum, plasma,
or whole blood).
Additives: Depending on the purpose, tubes may
contain anticoagulants, clot activators, or gel separators. Common
additives include:
EDTA (Ethylenediaminetetraacetic acid):
Prevents blood from clotting and is used for complete blood count (CBC)
tests.
Sodium Citrate: Used for coagulation studies by
binding calcium in the blood.
Heparin: Prevents clotting and is used for
plasma determinations.
Clot Activator: Promotes blood clotting for
serum collection.
Gel Separator: Aids in separating serum or
plasma from blood cells after centrifugation.
Advantages:
Convenient and Safe: The vacuum system
simplifies blood collection, reducing the risk of hemolysis and
contamination.
Precise Volumes: The vacuum ensures that the
correct volume of blood is drawn, which is crucial for accurate test
results.
Multiple Samples: Multiple tubes can be filled
during a single venipuncture, using a multi-sample needle, which
reduces patient discomfort.
Sterility: Vacuum tubes are sterile and sealed
until use, maintaining the integrity of the blood sample.
Common Types of Vacuum Blood Collection Tubes:
Red Top:
Additive: None (glass tube) or clot activator
(plastic tube).
Use: Serum collection for chemistry, serology,
and immunology tests.
Notes: After blood collection, the blood will
clot, and the serum can be separated by centrifugation.
Purple (Lavender) Top:
Additive: EDTA (Ethylenediaminetetraacetic
acid).
Use: Hematology tests such as Complete Blood
Count (CBC), blood smears, and HbA1c.
Notes: EDTA preserves cell morphology, making
it ideal for blood cell analysis.
Blue Top:
Additive: Sodium citrate.
Use: Coagulation studies, including Prothrombin
Time (PT) and Activated Partial Thromboplastin Time (APTT).
Notes: Sodium citrate binds calcium, preventing
blood from clotting. A proper blood-to-additive ratio is crucial.
Green Top:
Additive: Heparin (sodium, lithium, or
ammonium).
Use: Plasma determinations in chemistry tests,
blood gas analysis, and cytogenetic studies.
Notes: Heparin prevents clotting by inhibiting
thrombin and other clotting factors.
Yellow Top:
Additive: ACD (Acid Citrate Dextrose) or gel
separator with clot activator.
Use: ACD tubes are used for blood bank studies,
HLA phenotyping, and DNA testing. Gel separator tubes are used for
chemistry and serology tests.
Notes: The gel separator creates a physical
barrier between the serum/plasma and blood cells after
centrifugation.
Grey Top:
Additive: Potassium oxalate and sodium
fluoride.
Use: Glucose testing, lactate determination,
and blood alcohol levels.
Notes: Sodium fluoride preserves glucose by
inhibiting glycolysis.
Black Top:
Additive: Sodium citrate (in a different
concentration than the blue top).
Use: Erythrocyte Sedimentation Rate (ESR) test.
Notes: The tube is specifically designed to
measure the sedimentation rate of red blood cells.
Usage:
Preparation:
Ensure the correct tube is selected based on the required test.
Check the expiration date and integrity of the tube.
Blood Collection:
Attach the needle to the tube holder.
Perform venipuncture and insert the tube into the holder.
Allow the vacuum to draw the blood until the flow stops.
Remove the tube and gently invert it several times to mix the
blood with the additive.
Post-Collection:
Label the tube with patient information and the date of
collection.
Store and transport the sample according to the required
conditions.
Precautions:
Tube Selection
Correct Tube Type: Choose the appropriate tube
based on the required test (e.g., EDTA for hematology, sodium
citrate for coagulation studies). Using the wrong tube can result in
inaccurate or unusable results.
Additive Awareness: Be aware of the additives
in the tubes and their interactions with the blood sample. For
example, certain anticoagulants can interfere with specific tests.
Check Expiration Date
Expiration: Always check the expiration date of
the tube before use. Expired tubes may lose vacuum, causing
inadequate blood draw, or may have degraded additives, affecting
test results.
Proper Blood Draw Technique
Avoid Hemolysis: Handle tubes gently to avoid
hemolysis (rupture of red blood cells), which can interfere with
test results. Do not shake the tubes; gently invert them to mix the
blood with additives.
Correct Fill Volume: Ensure the tube is filled
to the appropriate volume. Underfilling or overfilling can alter the
blood-to-additive ratio, leading to inaccurate results.
Mixing of Additives
Gentle Inversion: After blood collection,
gently invert the tube 8-10 times to mix the blood with the additive
thoroughly. This is especially important for tubes with
anticoagulants to prevent clotting.
Immediate Mixing: Mix the tube immediately
after collection to ensure even distribution of the additive,
reducing the risk of clotting or other issues.
Avoid Cross-Contamination
Order of Draw: Follow the recommended order of
draw to prevent cross-contamination of additives between tubes. This
is critical when multiple tubes are drawn during a single
venipuncture.
Tube Caps: Keep tube caps on until ready to use
and avoid touching the inside of the cap or the tube’s opening to
maintain sterility.
Temperature and Storage Conditions
Temperature Control: Store and transport blood
samples at the recommended temperature to preserve sample integrity.
Some additives and blood components are temperature-sensitive.
Avoid Freezing: Do not freeze whole blood
samples unless required by the specific test, as freezing can cause
cell lysis and degrade certain analytes.
Handling Precautions
Proper Labeling: Immediately label the tube
with the patient’s information, date, and time of collection to
avoid mix-ups and ensure accurate tracking.
Avoid Excessive Pressure: Do not apply
excessive pressure when attaching or detaching the tube from the
needle holder, as this can cause hemolysis or loss of vacuum.
Transport Precautions
Upright Positioning: Transport tubes in an
upright position to minimize the risk of leakage and ensure proper
separation of blood components (e.g., in gel separator tubes).
Timely Transport: Ensure timely transport of
the sample to the laboratory to prevent degradation of analytes,
especially for time-sensitive tests.
Special Precautions for Certain Tests
Light Sensitivity: Protect samples for tests
like bilirubin or certain vitamins from light by using
light-blocking tubes or wrapping them in foil.
Anticoagulant Sensitivity: Be cautious with
anticoagulant tubes (e.g., sodium citrate) to maintain the correct
blood-to-additive ratio, as this directly impacts test results.
Disposal and Safety
Sharps Disposal: Dispose of needles and other
sharps in appropriate sharps containers to prevent needlestick
injuries.
Biohazard Precautions: Treat all blood
collection tubes as potentially infectious and dispose of them
according to biohazard regulations.
Adhering to these precautions when using vacuum blood collection
tubes is crucial for maintaining sample integrity, ensuring patient
safety, and obtaining accurate and reliable test results. Proper
technique, careful handling, and awareness of specific tube requirements
are key components of successful blood collection and testing.
Applications:
1. Hematology
Tubes Used: Lavender (Purple) Top (EDTA).
Applications:
Complete Blood Count (CBC): Measures
various components of blood, including red blood cells, white
blood cells, hemoglobin, and platelets.
Blood Smears: Used for microscopic
examination of blood cells to detect abnormalities.
HbA1c Testing: Monitors long-term glucose
control in diabetic patients.
2. Coagulation Studies
Tubes Used: Light Blue Top (Sodium Citrate).
Applications:
Prothrombin Time (PT): Assesses the blood’s
ability to clot, often used to monitor patients on anticoagulant
therapy.
Activated Partial Thromboplastin Time (APTT):
Evaluates the intrinsic pathway of coagulation.
Tubes Used: Red Top (Serum), Green Top
(Heparin), Yellow Top (Gel Separator), Grey Top (Sodium
Fluoride/Potassium Oxalate).
Applications:
Electrolyte Testing: Measures levels of
sodium, potassium, chloride, and bicarbonate in the blood.
Liver Function Tests (LFTs): Assesses liver
health by measuring enzymes like ALT, AST, and bilirubin.
Kidney Function Tests: Measures creatinine
and blood urea nitrogen (BUN) to evaluate kidney performance.
Glucose Testing: Monitors blood sugar
levels for diagnosing and managing diabetes.
Lipid Profile: Evaluates cholesterol and
triglyceride levels to assess cardiovascular risk.
Hormone Testing: Measures hormones like
thyroid-stimulating hormone (TSH), cortisol, and reproductive
hormones.
4. Serology and Immunology
Tubes Used: Red Top (Serum), Yellow Top (Gel
Separator with Clot Activator).
Applications:
Antibody Testing: Detects antibodies in the
blood, such as in HIV, hepatitis, or autoimmune diseases.
Antigen Testing: Identifies specific
antigens, such as those for infectious diseases.
Serum Protein Electrophoresis: Separates
proteins in the blood to diagnose conditions like multiple
myeloma.
5. Blood Banking
Tubes Used: Yellow Top (ACD).
Applications:
Blood Typing: Determines the blood type (A,
B, AB, O) and Rh factor of a patient.
Crossmatching: Ensures compatibility
between donor blood and recipient.
Antibody Screening: Detects unexpected
antibodies that may cause transfusion reactions.
6. Molecular Diagnostics
Tubes Used: Lavender Top (EDTA), Yellow Top (ACD),
Blue Top (Sodium Citrate).
Applications:
DNA/RNA Extraction: Collects blood for
genetic testing, such as PCR or sequencing.
HLA Typing: Used in transplantation
compatibility testing.
Viral Load Testing: Measures the amount of
virus in the blood for diseases like HIV or hepatitis.
7. Toxicology and Trace Element Testing
Tubes Used: Blue Top (Trace Element-Free), Grey
Top (Sodium Fluoride/Potassium Oxalate).
Applications:
Heavy Metal Testing: Measures levels of
metals like lead, mercury, or arsenic in the blood.
Drug Testing: Detects the presence of drugs
or their metabolites.
Alcohol Levels: Measures blood alcohol
concentration, often used in legal and forensic settings.
8. Microbiology
Tubes Used: Yellow Top (SPS), Blood Culture
Bottles.
Applications:
Blood Cultures: Detects bacterial or fungal
infections in the bloodstream.
Mycobacterial Cultures: Used for detecting
tuberculosis and other mycobacterial infections.
9. Erythrocyte Sedimentation Rate (ESR)
Tubes Used: Black Top (Sodium Citrate).
Applications:
Inflammation Detection: The ESR test
measures how quickly red blood cells settle at the bottom of a
tube, which can indicate inflammation or infection in the body.
Vacuum blood collection tubes are integral to a wide range of
diagnostic and research applications, each tailored to specific needs
through the use of various additives and designs. Understanding the
appropriate application for each tube type is crucial for accurate and
reliable results in clinical and laboratory settings.
Conclusion:
Vacuum blood collection tubes are a reliable and efficient method for
collecting blood samples in clinical and research settings.
Understanding the different types of tubes and their specific
applications is crucial for ensuring accurate and reliable test results.
Proper handling and usage are essential to maintain the integrity of the
blood sample and prevent pre-analytical errors.