ASCP PBT Practice Test: 30 Free Phlebotomy Questions
30 ASCP PBT-style questions with answers and explanations, weighted to the American Society for Clinical Pathology Board of Certification's Phlebotomy Technician exam. The real exam has 80 multiple-choice questions in 2 hours, and you need a scaled score of 400 to pass. No account needed: tap an answer to see why, and get your score and weakest area at the end.
Written by Benjamin Tibbs, a phlebotomy studentChecked against CLSI, OSHA, CDC and The Joint CommissionUpdated October 2026
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Answer: C. Polycythemia, because the high red cell mass makes blood more viscous
A hematocrit of 62% is far above the normal adult range and indicates polycythemia, in which the increased red cell mass makes blood thick and slow to flow. Avoid very small needles and make sure tubes fill completely. For coagulation testing, CLSI recommends adjusting the citrate volume when the hematocrit is above 55%, because the smaller plasma volume would otherwise leave too much anticoagulant.
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Answer: A. Remove the needle, because the pain suggests the needle is touching a nerve
Sharp, shooting, or electric pain that radiates down the arm or into the fingers signals that the needle may be touching a nerve. Stop and remove the needle at once; probing or redirecting can cause lasting nerve injury. Document the event and the patient's symptoms, and use another site if the specimen is still needed.
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Answer: D. From a peripheral vein, not through the line used to give the drug
Drug levels should reflect the patient's systemic concentration. Blood drawn through the catheter used to give the drug can contain residual drug and give a falsely high level. A peripheral venipuncture avoids that, and the actual collection time must be recorded so the trough can be interpreted.
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Answer: B. Perpendicular to the skin, across the fingerprint lines
Hold the lancet perpendicular to the skin on the fleshy pad of the fingertip, slightly off-center, so the cut runs across the fingerprint lines. A cut across the whorls lets a round drop form, while a cut along them lets blood run down the grooves. Angling the device also reduces the puncture depth it was designed to deliver.
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Answer: A. The ulnar artery can supply the hand if the radial artery is damaged
The modified Allen test checks collateral circulation before a radial artery puncture. The patient makes a fist while both the radial and ulnar arteries are compressed, then opens the hand and only the ulnar artery is released. If color returns within about 15 seconds, the ulnar artery can supply the hand; if not, that radial artery should not be punctured.
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Answer: D. Gray top
Gray-top tubes contain sodium fluoride, which stops glycolysis and preserves glucose, and potassium oxalate, which prevents clotting. They are used mainly for glucose, lactate, and blood alcohol testing. Without a glycolysis inhibitor, glucose in an unspun specimen falls by roughly 5 to 7% per hour.
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Answer: C. Record the actual time (9:12) and still draw the 2-hour specimen at 10:00
All OGTT specimens are timed from when the patient finished the glucose drink, not from the previous draw, so the 2-hour specimen stays at 10:00. The late specimen is drawn now and labeled with its actual collection time so the provider can interpret it. Whether the test must be repeated is the provider's decision.
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Answer: A. A non-alcohol antiseptic, such as aqueous povidone-iodine
Alcohol-based antiseptics can contaminate the specimen and falsely raise the blood alcohol result, which can then be challenged in court. Use a non-alcohol antiseptic, such as benzalkonium chloride or aqueous povidone-iodine, and follow chain-of-custody procedures. Many chlorhexidine prep pads also contain alcohol, so check the label.
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Answer: B. Light breaks down bilirubin, so the result may be falsely low
Bilirubin breaks down when exposed to light, including ordinary fluorescent room lighting, so exposure lowers the result. The loss builds up over time (roughly 5–7% per hour under lab lighting in one study), which matters in newborns, whose bilirubin levels guide phototherapy decisions. Protect bilirubin specimens with an amber tube or foil wrap from collection to testing, and keep light exposure to a minimum.
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Answer: D. Use a prewarmed tube and hold it at body temperature until the serum is separated
Cryoglobulins are proteins that precipitate when serum cools below body temperature. If the specimen cools before the serum is separated, they are trapped in the clot and the result is falsely low or negative. Use a prewarmed tube and keep the specimen at 37°C until the lab separates the serum; the lab then cools it deliberately to look for the precipitate.
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Answer: B. Ammonia and lactic acid, because both rise from ongoing cell metabolism
After collection, blood cells keep metabolizing: ammonia rises as amino acids break down, and lactate rises from glycolysis. Chilling slows both, so these tubes go on ice and to the lab promptly. The EDTA tube for the CBC stays at room temperature, since chilling it is unnecessary and can affect some results.
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Answer: C. Report it now and send a venous sample to the lab to confirm
In patients with poor circulation, such as those in shock or on vasopressors, fingerstick glucose results can be inaccurate, and glucose meters are not FDA-cleared for capillary fingerstick testing in critically ill patients. A result this low is reported to the nurse right away, and a venous specimen tested in the laboratory confirms the true value. Ignoring it or repeating the same unreliable test delays care.
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Answer: A. Retract the foreskin, clean the urethral opening, start voiding into the toilet, then collect midstream
The first part of the stream flushes bacteria from the urethra, so it goes into the toilet; the midstream portion better reflects bladder urine. Cleaning the urethral opening and, in uncircumcised males, keeping the foreskin retracted reduce skin contamination. The patient finishes voiding into the toilet and caps the sterile container without touching the inside.
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Answer: D. Stop patient testing, document the QC failure, and troubleshoot
Consecutive QC results beyond 2 SD on the same side of the mean break the Westgard 2:2s rule and point to a systematic error. Patient testing stops until the problem is found and corrected and QC is back in range, because patient values that look normal may still be wrong. Changing the limits to fit a failing result hides the problem instead of fixing it.
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Answer: B. Pre-labeled tubes can end up filled with another patient's blood
The Joint Commission requires specimen containers to be labeled in the presence of the patient (NPG.01.01.01, formerly NPSG.01.01.01), and CLSI calls for labeling immediately after collection. Pre-labeled tubes can be used for the wrong patient, creating a wrong-blood-in-tube error. In blood bank testing, that kind of error can lead to an ABO-incompatible transfusion.
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Answer: A. The gold top yields serum, which lacks fibrinogen used up in clotting
When blood clots, fibrinogen is converted into the fibrin of the clot, so serum (the liquid left after clotting in a red or gold tube) has no fibrinogen. A light blue tube contains sodium citrate, an anticoagulant, so it yields plasma, which keeps fibrinogen and the other clotting factors that coagulation tests measure.
Review: Anatomy & Circulatory System
Why the other choices are wrong
- B. Reversed: a clot-activator tube yields serum. Plasma comes from anticoagulated tubes.
- C. Citrate prevents clotting by binding calcium; it does not make blood clot. The light blue top yields plasma.
- D. Serum and plasma differ in a way that matters for testing: plasma keeps fibrinogen and clotting factors, serum does not.
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Answer: B. The radial artery
The radial artery is preferred: it lies near the surface, is easy to compress afterward, and when the ulnar artery supplies collateral flow to the hand (checked with a modified Allen test) the hand stays perfused even if the radial artery is injured. The brachial and femoral arteries are used only when the radial cannot be.
Why the other choices are wrong
- A. The brachial artery is a second choice: it is deeper, has less collateral circulation, and lies next to the median nerve.
- C. The femoral artery is a last resort with poor collateral circulation and higher risk, usually punctured by physicians or specially trained staff.
- D. The ulnar artery provides the collateral flow to the hand. It is the artery being protected, not the one punctured.
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Answer: C. A deeper puncture can reach the heel bone and cause infection
CLSI GP42-Ed7 limits infant heel punctures to the medial or lateral plantar surface of the heel and to a depth of 2.0 mm, because in small infants the calcaneus (heel bone) can lie closer than that to the skin. Puncturing the bone can cause osteomyelitis.
Why the other choices are wrong
- A. Tissue fluid contamination comes mainly from squeezing the site, not from the depth of the puncture.
- B. Hemolysis at a heel stick usually comes from squeezing or scraping the drops, not from depth.
- D. The depth limit exists to protect the heel bone, which can lie less than 2 mm under the skin in small infants.
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Answer: D. It is likely to contain tissue fluid or residual alcohol
CLSI GP42-Ed7 directs that the first drop be wiped away with clean gauze, because it tends to carry tissue fluid and may contain alcohol left from skin cleansing, either of which can affect results. For point-of-care devices, follow the manufacturer's instructions.
Why the other choices are wrong
- A. Platelet clumping is prevented by collecting promptly and mixing, not by discarding the first drop.
- B. A clean lancet puncture does not hemolyze the first drop. The concern is tissue fluid and alcohol.
- C. The first drop has not clotted. The problem is contamination, not clotting.
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Answer: A. A 23-gauge butterfly with small-volume tubes
For small, fragile veins a 23-gauge winged (butterfly) set gives control at a shallow angle, and small-volume tubes (or a syringe) pull with less vacuum, so the vein is less likely to collapse. Higher gauge numbers mean smaller needles; 21 gauge is standard for antecubital veins, and needles finer than 23 gauge raise the risk of hemolysis.
Why the other choices are wrong
- B. A 21-gauge straight needle with standard tubes is the routine antecubital setup. On small fragile veins the strong vacuum can collapse them.
- C. 18 gauge is a large-bore needle, used for blood donation, and far too large for a small hand vein.
- D. Needles finer than 23 gauge increase hemolysis, and large-volume tubes pull hard enough to collapse a small vein.
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Answer: B. Anchor it by pulling the skin taut below the site
Anchoring holds the vein in place: the thumb of the non-dominant hand pulls the skin taut below the site, never above it in the needle's path. A shallow angle (about 15 to 30 degrees) and a smooth, steady insertion then enter the vein instead of pushing it aside.
Why the other choices are wrong
- A. A steep angle risks passing through the back wall of the vein. A routine draw uses a shallow angle.
- C. A tighter tourniquet does not stop a vein from rolling, and it can restrict arterial flow and cause hemoconcentration.
- D. Vigorous fist pumping does not steady the vein, and it falsely raises potassium.
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Answer: C. Draw from the right arm and leave the fistula arm alone
The arm with a dialysis fistula or graft is not used for venipuncture, tourniquets or blood pressures unless the patient's physician authorizes it, because a puncture or compression can damage or clot the access the patient depends on for dialysis. Draw from the other arm.
Why the other choices are wrong
- A. Only dialysis staff access a fistula, for dialysis. A phlebotomy puncture risks bleeding, infection and loss of the access.
- B. Any puncture or tourniquet on the access arm can damage the fistula, even away from it.
- D. A tourniquet on the fistula arm, however brief, compresses the access and can damage or clot it.
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Answer: A. Use the forearm vein below (distal to) the hematoma
A hematoma is not punctured: it is painful, and the specimen can be contaminated with blood that has leaked into the tissue. When another site on the same arm must be used, it should be below (distal to) the hematoma, so the blood collected has not passed through the injured area.
Why the other choices are wrong
- B. Puncturing a hematoma is painful, and the specimen can be contaminated with blood that leaked into the tissue.
- C. Venous blood flows toward the heart, so blood drawn above the hematoma has passed through the injured area.
- D. Massaging a hematoma can enlarge it. The injured tissue is avoided altogether.
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Answer: B. Reject the specimen and request a recollection
A clot in an EDTA tube means cells and platelets have been trapped and used up, so the counts (platelets especially) are falsely low and the specimen cannot be used for a CBC. It is rejected and recollected. Clots usually come from delayed or inadequate mixing right after the draw; BD EDTA tubes are inverted 8 to 10 times.
Why the other choices are wrong
- A. Removing the clot also removes the cells and platelets trapped in it, so the counts are still wrong.
- C. A comment does not make the results usable. A clotted CBC gives falsely low counts.
- D. Mixing cannot dissolve a clot once fibrin has formed.
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Answer: C. Pipette the serum into a labeled aliquot tube and freeze it
Whole blood is never frozen: ice crystals rupture the red cells, and the thawed specimen is hemolyzed. The specimen is clotted and centrifuged, the serum is transferred with a pipette into a plastic aliquot tube labeled with the same patient identifiers, and the aliquot is frozen as the test requires.
Why the other choices are wrong
- A. Freezing whole blood ruptures the red cells, so the thawed specimen is hemolyzed.
- B. An analyte that must be frozen is not stable at room temperature. Waiting degrades it.
- D. Refrigeration (2 to 8 °C) is not freezing. An analyte that requires freezing degrades in the refrigerator.
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Answer: D. Hold patient testing until the controls pass
A waived laboratory must follow the manufacturer's instructions (CLIA, 42 CFR 493.15(e)), and those require controls to be in range before patient testing. When a control fails, patient testing stops: check the strips' lot, expiration date and storage, rerun the controls, and follow the meter's troubleshooting steps. Testing resumes only when both controls are acceptable.
Why the other choices are wrong
- A. Each control checks part of the measuring range. A failed high control means high patient results may be wrong.
- B. Results produced after a failed control cannot be trusted. Troubleshooting comes before patient testing, not at the end of the shift.
- C. Results are never corrected by hand. That would report a number the meter did not measure.
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Answer: A. Both tonsils and the back of the throat
CDC guidance for group A strep pharyngitis is to swab both tonsils and the posterior pharynx vigorously. Touching the tongue, cheeks, teeth or lips picks up mouth flora and can dilute the specimen, so a tongue depressor keeps the swab clear of them.
Why the other choices are wrong
- B. The cheeks and gums carry normal mouth bacteria and are not where strep infects; touching them contaminates the swab.
- C. Saliva from the tongue dilutes the specimen with mouth flora, so the tongue is avoided.
- D. A nasal swab samples a different site. Strep pharyngitis is tested from the tonsils and throat.
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Answer: B. Flush the eye at an eyewash station for at least 15 minutes
A chemical in the eye is flushed with water right away for at least 15 minutes, holding the eyelids open (ANSI/ISEA Z358.1; bleach Safety Data Sheets give the same first aid). OSHA 29 CFR 1910.151(c) requires eyewash facilities where corrosive materials are used. Report the injury and get medical evaluation afterward.
Why the other choices are wrong
- A. A brief rinse leaves chemical in the eye, and damage can continue before symptoms appear.
- C. Never put another chemical in the eye; a neutralizing reaction can add injury. Flush with water.
- D. Covering the eye traps the chemical against it. Flush first, then report.
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Answer: C. One rated for Class C, such as an ABC or CO2 unit
Fires in energized electrical equipment are Class C. Use an extinguisher rated for Class C, such as a multipurpose ABC dry chemical or carbon dioxide unit, never water, which conducts electricity. Unplug the equipment if it is safe to do so, and follow the facility fire plan.
Why the other choices are wrong
- A. Water conducts electricity and can shock the user on an energized electrical fire.
- B. Class K is for cooking oils and fats, not electrical equipment.
- D. The class matters for every fire: the wrong agent can spread the fire or endanger the user.
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Answer: D. The specimen may be from the wrong patient
A delta check compares a result with the same patient's previous result. A large change that the patient's care cannot explain, such as hemoglobin rising 5 g/dL overnight without a transfusion, is a classic sign of a misidentified or mislabeled specimen, so the laboratory investigates and usually recollects before reporting.
Why the other choices are wrong
- A. Calibration problems affect many patients' results and show up in quality control, not as one patient's change from yesterday.
- B. Hemoglobin cannot rise 5 g/dL overnight without a transfusion. The change is not physiologically plausible.
- C. A control failure stops patient testing on the analyzer. A delta flag concerns one patient's history.
More free practice tests
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The three phlebotomy certification exams
Question counts, time limits and passing scores from each certifying body's own documents, checked October 6, 2026.
| Exam | Questions | Time | Passing score | Practice |
|---|---|---|---|---|
| NHA CPTNational Healthcareer Association | 120 questions: 100 scored and 20 unscored pretest items | 2 hours | 390 (scaled score from 200 to 500) | NHA CPT practice exam |
| ASCP PBTAmerican Society for Clinical Pathology Board of Certification | 80 multiple-choice questions | 2 hours | 400 (scaled score) | This page |
| AMT RPTAmerican Medical Technologists | 200 scored questions (AMT exams may also include unscored pretest items) | 2.5 hours | 70 (scaled score from 0 to 100) | AMT RPT practice exam |
More detail: how each exam is scored · retake rules · NHA vs ASCP vs AMT · all exam facts with sources · general phlebotomy practice test