NCCT Phlebotomy Exam Prep Questions And
Well Graded Solutions With
Rationales Updated 2026-2027
Pass your National Certified Phlebotomy Technician exam with this ultimate NCCT
Phlebotomy study guide. Features comprehensive practice questions, verified answers,
and detailed clinical rationales. Master critical domains: CLSI order of draw, specimen
collection, capillary punctures, tubes, safety protocols, and OSHA regulations. Perfect
prep material for students at top healthcare programs looking to ace the test on the first
try and earn their national NCPT certification
1. Which of the following tubes must be drawn first to prevent cross-contamination of
additives?
A) Light Blue
B) Green
C) Lavender
D) Yellow (Blood Culture)
Correct Answer: D
Rationale: Blood culture tubes or vials are drawn first to maintain strict
sterility and prevent bacterial contamination from the stoppers of other tubes.
2. A phlebotomist must draw a PT/INR and a CBC. Which of the following describes the
correct order of draw?
A) Lavender, then Light Blue
B) Light Blue, then Lavender
C) Serum, then Green
D) Green, then Lavender
Correct Answer: B
Rationale: Light Blue (coagulation) must always be drawn before Lavender
(hematology) to prevent EDTA carryover, which would falsely elevate
coagulation times.
3. What additive is contained inside a plastic light blue top tube?
A) Sodium Heparin
B) Sodium Citrate
C) EDTA
D) Potassium Oxalate
Correct Answer: B
Rationale: Light blue tubes contain sodium citrate, an anticoagulant that binds
calcium to preserve coagulation factors for plasma testing.
4. Which tube contains an anticoagulant that works by inhibiting thrombin?
A) Green
B) Light Blue
C) Lavender
D) Gray
Correct Answer: A
Rationale: Green top tubes contain heparin (lithium or sodium), which inhibits
thrombin formation to prevent clotting for plasma chemistry tests.
5. If a practitioner orders a fasting blood glucose and a CBC, which tubes should be
selected?
, A) Red and Green
B) Gray and Lavender
C) Light Blue and Gold
D) Yellow and Gray
Correct Answer: B
Rationale: Gray tubes contain sodium fluoride/potassium oxalate for glucose
preservation, and Lavender tubes contain EDTA for the complete blood count
(CBC).
6. What is the primary purpose of the additive sodium fluoride in a gray top tube?
A) To promote rapid clotting
B) To preserve coagulation factors
C) To inhibit glycolysis
D) To prevent platelet aggregation
Correct Answer: C
Rationale: Sodium fluoride is an antiglycolytic agent that preserves glucose by
preventing its breakdown by cells for up to 3 days.
7. Which of the following can occur if a lavender top tube is underfilled?
A) The sample will clot immediately
B) Red blood cells will shrink and alter morphology
C) The glucose level will drop rapidly
D) Falsely decreased prothrombin time
Correct Answer: B
Rationale: Underfilling a lavender tube leaves an excess of EDTA relative to
the blood volume, causing red blood cells to shrink and distorting cell counts.
8. A phlebotomist is using a butterfly needle to collect a light blue tube only. What must
be done first?
A) Draw a waste/discard tube to clear line air
B) Shake the tube vigorously
C) Advance the needle deeper into the vein
D) Apply a warm compress to the tube
Correct Answer: A
Rationale: A discard tube must be drawn first to displace the air in the butterfly
tubing, ensuring the light blue tube fills completely to maintain the critical 9:1
blood-to-anticoagulant ratio.
9. What is the correct inversion frequency for a serum separator tube (SST/Gold)?
A) 0 times
B) 3 to 4 times
C) 5 to 8 times
D) 10 to 12 times
Correct Answer: C
Rationale: SST and clot activator tubes require 5 to 8 inversions to mix the clot
activator thoroughly with the blood sample.
10. Which tube is specifically designated for lead determinations?
A) Tan or Royal Blue with EDTA
B) Light Blue
C) Gray
D) Green
, Correct Answer: A
Rationale: Tan top tubes or royal blue tubes labeled with EDTA are certified to
contain trace-element-free environments, crucial for accurate lead testing.
11. Which micro-collection container should be collected first during a capillary
puncture?
A) Blood gas specimens
B) EDTA (Lavender)
C) Other additive tubes (Green)
D) Non-additive tubes (Red)
Correct Answer: A
Rationale: Blood gases are collected first from a capillary puncture to
minimize exposure to air, followed immediately by EDTA to prevent micro-clot
formation.
12. Why is the order of draw for capillary punctures different from venipuncture?
A) Capillary blood clots much slower
B) Platelets aggregate rapidly at skin puncture sites
C) Anticoagulants do not work in capillary tubes
D) Fluid shifts cause immediate hemolysis
Correct Answer: B
Rationale: Skin punctures initiate the clotting process instantly; therefore,
hematology tubes (EDTA) are collected first to prevent micro-clots from
altering cell counts.
13. Which of the following tests is highly sensitive to light and must be protected during
transport?
A) Potassium
B) Bilirubin
C) Blood Urea Nitrogen (BUN)
D) Hemoglobin
Correct Answer: B
Rationale: Bilirubin is rapidly degraded when exposed to light, requiring the
sample to be drawn in an amber tube or wrapped completely in aluminum foil.
14. What occurs when a phlebotomist vigorously shakes a blood collection tube instead
of inverting it?
A) Hemoconcentration
B) Glycolysis
C) Hemolysis
D) Hemostasis
Correct Answer: C
Rationale: Vigorous shaking ruptures red blood cells, causing hemolysis,
which leaks intracellular contents like potassium into the serum or plasma.
15. Thixotropic gel is an additive found in which type of tube?
A) Red-top glass tubes
B) Serum Separator Tubes (SST)
C) EDTA tubes
D) Sodium Citrate tubes
Correct Answer: B
Rationale: Thixotropic gel is a density barrier found in SST (Gold) and PST
, (Light Green) tubes that separates cells from serum or plasma during
centrifugation.
16. Which tube is used to collect samples for blood bank cross-matching?
A) Pink (EDTA)
B) Gray
C) Light Blue
D) Gold
Correct Answer: A
Rationale: Pink top tubes contain EDTA and feature specialized labeling
mechanisms explicitly designated for blood bank patient identification and
compatibility testing.
17. What is the correct ratio of blood to anticoagulant in a light blue sodium citrate tube?
A) 1:1
B) 4:1
C) 9:1
D) 2:1
Correct Answer: C
Rationale: A strict 9:1 ratio of blood to sodium citrate is mandatory for
accurate coagulation testing; deviations will yield invalid test results.
18. If a chemistry test requires serum, which tube color should the phlebotomist select?
A) Green
B) Red or Gold
C) Lavender
D) Gray
Correct Answer: B
Rationale: Red or Gold (SST) tubes allow the blood to clot, producing serum
after centrifugation. Green, lavender, and gray tubes produce plasma.
19. Which of the following additives stops coagulation by precipitating calcium?
A) Lithium Heparin
B) Potassium Oxalate
C) Sodium Polyanethol Sulfonate
D) Silica Clot Activator
Correct Answer: B
Rationale: Potassium oxalate (found in gray tubes) prevents clotting by
precipitating calcium out of the blood solution.
20. A patient needs a STAT electrolytes panel. Which tube allows for rapid processing
without waiting for a clot?
A) Red (Glass)
B) Gold (SST)
C) Light Green (PST with Lithium Heparin)
D) Tiger Top
Correct Answer: C
Rationale: Light green plasma separator tubes contain heparin, which
prevents clotting completely, allowing immediate centrifugation and faster
processing for emergency (STAT) chemistry results.
Well Graded Solutions With
Rationales Updated 2026-2027
Pass your National Certified Phlebotomy Technician exam with this ultimate NCCT
Phlebotomy study guide. Features comprehensive practice questions, verified answers,
and detailed clinical rationales. Master critical domains: CLSI order of draw, specimen
collection, capillary punctures, tubes, safety protocols, and OSHA regulations. Perfect
prep material for students at top healthcare programs looking to ace the test on the first
try and earn their national NCPT certification
1. Which of the following tubes must be drawn first to prevent cross-contamination of
additives?
A) Light Blue
B) Green
C) Lavender
D) Yellow (Blood Culture)
Correct Answer: D
Rationale: Blood culture tubes or vials are drawn first to maintain strict
sterility and prevent bacterial contamination from the stoppers of other tubes.
2. A phlebotomist must draw a PT/INR and a CBC. Which of the following describes the
correct order of draw?
A) Lavender, then Light Blue
B) Light Blue, then Lavender
C) Serum, then Green
D) Green, then Lavender
Correct Answer: B
Rationale: Light Blue (coagulation) must always be drawn before Lavender
(hematology) to prevent EDTA carryover, which would falsely elevate
coagulation times.
3. What additive is contained inside a plastic light blue top tube?
A) Sodium Heparin
B) Sodium Citrate
C) EDTA
D) Potassium Oxalate
Correct Answer: B
Rationale: Light blue tubes contain sodium citrate, an anticoagulant that binds
calcium to preserve coagulation factors for plasma testing.
4. Which tube contains an anticoagulant that works by inhibiting thrombin?
A) Green
B) Light Blue
C) Lavender
D) Gray
Correct Answer: A
Rationale: Green top tubes contain heparin (lithium or sodium), which inhibits
thrombin formation to prevent clotting for plasma chemistry tests.
5. If a practitioner orders a fasting blood glucose and a CBC, which tubes should be
selected?
, A) Red and Green
B) Gray and Lavender
C) Light Blue and Gold
D) Yellow and Gray
Correct Answer: B
Rationale: Gray tubes contain sodium fluoride/potassium oxalate for glucose
preservation, and Lavender tubes contain EDTA for the complete blood count
(CBC).
6. What is the primary purpose of the additive sodium fluoride in a gray top tube?
A) To promote rapid clotting
B) To preserve coagulation factors
C) To inhibit glycolysis
D) To prevent platelet aggregation
Correct Answer: C
Rationale: Sodium fluoride is an antiglycolytic agent that preserves glucose by
preventing its breakdown by cells for up to 3 days.
7. Which of the following can occur if a lavender top tube is underfilled?
A) The sample will clot immediately
B) Red blood cells will shrink and alter morphology
C) The glucose level will drop rapidly
D) Falsely decreased prothrombin time
Correct Answer: B
Rationale: Underfilling a lavender tube leaves an excess of EDTA relative to
the blood volume, causing red blood cells to shrink and distorting cell counts.
8. A phlebotomist is using a butterfly needle to collect a light blue tube only. What must
be done first?
A) Draw a waste/discard tube to clear line air
B) Shake the tube vigorously
C) Advance the needle deeper into the vein
D) Apply a warm compress to the tube
Correct Answer: A
Rationale: A discard tube must be drawn first to displace the air in the butterfly
tubing, ensuring the light blue tube fills completely to maintain the critical 9:1
blood-to-anticoagulant ratio.
9. What is the correct inversion frequency for a serum separator tube (SST/Gold)?
A) 0 times
B) 3 to 4 times
C) 5 to 8 times
D) 10 to 12 times
Correct Answer: C
Rationale: SST and clot activator tubes require 5 to 8 inversions to mix the clot
activator thoroughly with the blood sample.
10. Which tube is specifically designated for lead determinations?
A) Tan or Royal Blue with EDTA
B) Light Blue
C) Gray
D) Green
, Correct Answer: A
Rationale: Tan top tubes or royal blue tubes labeled with EDTA are certified to
contain trace-element-free environments, crucial for accurate lead testing.
11. Which micro-collection container should be collected first during a capillary
puncture?
A) Blood gas specimens
B) EDTA (Lavender)
C) Other additive tubes (Green)
D) Non-additive tubes (Red)
Correct Answer: A
Rationale: Blood gases are collected first from a capillary puncture to
minimize exposure to air, followed immediately by EDTA to prevent micro-clot
formation.
12. Why is the order of draw for capillary punctures different from venipuncture?
A) Capillary blood clots much slower
B) Platelets aggregate rapidly at skin puncture sites
C) Anticoagulants do not work in capillary tubes
D) Fluid shifts cause immediate hemolysis
Correct Answer: B
Rationale: Skin punctures initiate the clotting process instantly; therefore,
hematology tubes (EDTA) are collected first to prevent micro-clots from
altering cell counts.
13. Which of the following tests is highly sensitive to light and must be protected during
transport?
A) Potassium
B) Bilirubin
C) Blood Urea Nitrogen (BUN)
D) Hemoglobin
Correct Answer: B
Rationale: Bilirubin is rapidly degraded when exposed to light, requiring the
sample to be drawn in an amber tube or wrapped completely in aluminum foil.
14. What occurs when a phlebotomist vigorously shakes a blood collection tube instead
of inverting it?
A) Hemoconcentration
B) Glycolysis
C) Hemolysis
D) Hemostasis
Correct Answer: C
Rationale: Vigorous shaking ruptures red blood cells, causing hemolysis,
which leaks intracellular contents like potassium into the serum or plasma.
15. Thixotropic gel is an additive found in which type of tube?
A) Red-top glass tubes
B) Serum Separator Tubes (SST)
C) EDTA tubes
D) Sodium Citrate tubes
Correct Answer: B
Rationale: Thixotropic gel is a density barrier found in SST (Gold) and PST
, (Light Green) tubes that separates cells from serum or plasma during
centrifugation.
16. Which tube is used to collect samples for blood bank cross-matching?
A) Pink (EDTA)
B) Gray
C) Light Blue
D) Gold
Correct Answer: A
Rationale: Pink top tubes contain EDTA and feature specialized labeling
mechanisms explicitly designated for blood bank patient identification and
compatibility testing.
17. What is the correct ratio of blood to anticoagulant in a light blue sodium citrate tube?
A) 1:1
B) 4:1
C) 9:1
D) 2:1
Correct Answer: C
Rationale: A strict 9:1 ratio of blood to sodium citrate is mandatory for
accurate coagulation testing; deviations will yield invalid test results.
18. If a chemistry test requires serum, which tube color should the phlebotomist select?
A) Green
B) Red or Gold
C) Lavender
D) Gray
Correct Answer: B
Rationale: Red or Gold (SST) tubes allow the blood to clot, producing serum
after centrifugation. Green, lavender, and gray tubes produce plasma.
19. Which of the following additives stops coagulation by precipitating calcium?
A) Lithium Heparin
B) Potassium Oxalate
C) Sodium Polyanethol Sulfonate
D) Silica Clot Activator
Correct Answer: B
Rationale: Potassium oxalate (found in gray tubes) prevents clotting by
precipitating calcium out of the blood solution.
20. A patient needs a STAT electrolytes panel. Which tube allows for rapid processing
without waiting for a clot?
A) Red (Glass)
B) Gold (SST)
C) Light Green (PST with Lithium Heparin)
D) Tiger Top
Correct Answer: C
Rationale: Light green plasma separator tubes contain heparin, which
prevents clotting completely, allowing immediate centrifugation and faster
processing for emergency (STAT) chemistry results.
