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Quizzes > Health & Medicine > Human Anatomy & Medicine

Order of Draw Phlebotomy Quiz: Test Your Knowledge

Think you can master the phlebotomy order of draw? Start the quiz now!

Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art illustration for phlebotomy quiz on golden yellow background

This Order of Draw Phlebotomy Quiz helps you practice tube sequencing and confirm the correct order for common tests. Use it to spot gaps before a skills check or exam. Need a quick color refresher? Open the tube color guide , then come back or try more in the full practice set .

Which tube is collected first in the standard order of draw for venipuncture?
Blood culture bottle
Lavender tube
Light blue tube
Serum tube (red top)
According to standard phlebotomy guidelines, blood culture bottles are drawn first to minimize contamination and ensure accurate microbiological results. Following them, coagulation tubes and serum tubes are collected. Drawing cultures first helps prevent skin flora or additive carryover from affecting microbiology tests.
Which additive is contained in the lavender top tube?
Potassium oxalate
Ethylenediaminetetraacetic acid (EDTA)
Sodium citrate
Heparin
Lavender top tubes contain EDTA, which works by chelating calcium to prevent blood from clotting and preserve cellular elements for hematology tests. This additive is preferred for complete blood counts and blood smears. EDTA must be the only anticoagulant present to avoid interference with cell morphology.
Why is it important to follow the order of draw during phlebotomy?
To standardize tube colors in labs
To prevent additive carryover and contamination between tubes
To minimize needle-stick injuries
To reduce the time of the draw
Following the prescribed order of draw prevents additives in earlier tubes from contaminating later samples, which can alter test results. For example, EDTA carryover into a coagulation tube can cause falsely prolonged clotting times. Maintaining this sequence ensures specimen integrity and reliability of lab values.
Which tube is specifically used for glucose measurement and contains glycolysis inhibitors?
Green top tube
Light blue tube
Gray top tube
Red top tube
Gray top tubes contain sodium fluoride and potassium oxalate; the fluoride inhibits glycolysis and preserves glucose concentration. This additive combination stabilizes glucose levels for several hours at room temperature. It is essential for accurate blood glucose testing and tolerance tests.
After collecting a light blue top tube (sodium citrate), which tube should be drawn next in the correct order of draw?
Gray top tube
Green top tube
Serum tube (red top)
Lavender top tube
The standard order of draw places serum tubes (red top) after coagulation tubes (light blue) to prevent carryover of citrate into serum samples. This sequence aligns with CLSI guidelines for tube collection. Next follow heparin, EDTA, and glycolysis inhibitor tubes.
How many gentle inversions are recommended for a green top tube containing lithium heparin to ensure proper mixing?
8 - 10 inversions
5 - 6 inversions
3 - 4 inversions
15 - 20 inversions
Green top tubes with lithium heparin require 8 - 10 gentle inversions to mix the anticoagulant thoroughly with blood and prevent clotting. Under-mixing can lead to microclots; over-mixing can cause hemolysis. Following the manufacturer's recommended inversion count ensures specimen quality.
Which tube stopper color indicates the presence of a silica clot activator and gel for serum separation?
Gold (tiger top) tube
Red top tube
Green top tube
Lavender top tube
Gold or tiger top tubes are serum separator tubes containing a silica clot activator and a gel barrier. The silica accelerates clot formation, and the gel creates a physical barrier between cells and serum after centrifugation. This ensures clear serum for chemistry testing.
Which tube should be drawn immediately before the lavender top tube in the standard order of draw?
Red top tube
Light blue top tube
Green top tube (heparin)
Gray top tube
In the order of draw, heparin tubes (green top) are collected before EDTA tubes (lavender top). Drawing lavender after green prevents heparin carryover from affecting hematology tests. Following this sequence preserves test accuracy and sample integrity.
What is a potential consequence if an EDTA tube is drawn before a citrate (light blue) tube?
Hyperkalemia artifact
Elevated glucose levels
Increased bacterial contamination
Falsely prolonged prothrombin time (PT)
EDTA chelates calcium and, if carried over into a citrate tube, will bind additional calcium necessary for coagulation tests, causing falsely prolonged PT and aPTT results. Proper tube sequence is critical to avoid additive contamination. This is outlined in CLSI GP41 guidelines.
In capillary microcollection, which microtube should be filled first to minimize clot formation?
EDTA microtube for hematology
Gray microtube for glucose
Heparin microtube for blood gas
Serum microtube for chemistry
For capillary collections, the EDTA microtube is filled first to prevent microclot formation in small-volume samples and ensure accurate hematology results. Filling EDTA first reduces the risk of clotting before enough blood is collected. CLSI C27-A3 details this recommended sequence.
When using a winged infusion set (butterfly) with tubing, what should be drawn first to prevent additive contamination?
Light blue top tube
Serum separator tube
Lavender top tube
A discard (waste) tube
With butterfly sets, the tubing volume may contain air or previous additive residue. Drawing a discard tube first clears the tubing so subsequent evacuated tubes contain uncontaminated blood. This step protects test integrity for all downstream tubes.
When collecting blood for both coagulation studies and therapeutic drug monitoring in one draw, which tube should follow the citrate (light blue) tube to ensure accurate drug level measurement?
Serum separator tube (gold top)
Lavender top tube
Green top tube
Gray top tube
After the citrate tube for coagulation studies, drawing a serum separator tube (gold top) ensures proper specimen for therapeutic drug monitoring. The gel barrier and clot activator provide clear serum and prevent additive interference. This sequence maintains accuracy for both coagulation and drug assays.
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Study Outcomes

  1. Understand Correct Tube Sequencing -

    Understand the standard order of draw phlebotomy procedure by sequencing blood collection tubes correctly to maintain sample quality and prevent contamination.

  2. Identify Tube Colors and Additives -

    Identify common tube colors used in venepuncture order of draw and match each color to its specific additive and clinical purpose.

  3. Apply Proper Venepuncture Protocol -

    Apply best practices for the order of draw for labs during venipuncture to ensure accurate laboratory results and patient safety.

  4. Analyze Cross-Contamination Risks -

    Analyze how incorrect tube sequencing can lead to sample contamination and erroneous test outcomes, and learn to avoid these pitfalls.

  5. Differentiate Laboratory Test Requirements -

    Differentiate which blood tests require specific tubes and additives by correlating test types with the appropriate order of draw phlebotomy sequence.

  6. Prepare for Order of Draw Test Success -

    Prepare effectively for phlebotomy exams by practicing the order of draw test and receiving instant feedback to reinforce your learning.

Cheat Sheet

  1. Purpose of Order of Draw -

    Following the order of draw phlebotomy guidelines from CLSI and WHO prevents additive carryover and cross-contamination between tubes. For example, if an EDTA tube is drawn before a serum tube, calcium-chelating can falsely lower measured calcium levels. Understanding this principle ensures reliable lab results and patient safety.

  2. Standard Tube Sequence -

    The classic sequence is sterile (yellow), citrate (light blue), serum (red or gold), heparin (green), EDTA (lavender), and glycolytic inhibitor (gray). A popular mnemonic is "Stop Light Red, Green, Light, Gray" to lock in the correct order. Mastering this order of draw for labs is critical for accurate diagnostics.

  3. Additive Functions and Effects -

    Each tube's additive has a specific role: sodium citrate binds calcium for coagulation studies, EDTA chelates calcium for hematology, and heparin inhibits thrombin for chemistry tests. Recognizing how these additives work helps prevent analytical interference, such as EDTA-induced pseudothrombocytopenia. Review additive mechanisms from authoritative sources like the Journal of Clinical Laboratory Science.

  4. Proper Mixing Technique -

    After collection, gently invert tubes the recommended number of times - usually 3 - 8 inversions - to mix blood with additives. Vigorous shaking can cause hemolysis, altering potassium and LDH readings, while under-mixing may lead to clot formation in EDTA tubes. Practice the correct inversion count to maintain sample integrity.

  5. Clinical Implications of Errors -

    Incorrect order of draw or tube handling can lead to misdiagnoses, such as hyperkalemia from hemolysis or clotting in coagulation tests. For instance, drawing a gray-top tube too early can prematurely halt glycolysis and skew glucose results. Emphasize this in venepuncture order of draw training to minimize patient risk and lab retests.

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