Phlebotomy Specimen Handling Quiz: 12 Free Questions
Twelve questions on what happens to a specimen after the needle comes out: labeling in military time and at the bedside, which specimens need light protection, ice or body temperature, serum versus plasma, how fast serum comes off the cells, and how coagulation tubes and blood cultures travel. Each answer is explained, wrong options included, with the laboratory source it was checked against. Review the specimen handling guide first, or take the quiz cold and see where you stand. No account needed.
Written by Benjamin Tibbs, a phlebotomy studentChecked against CLSI, OSHA, CDC and The Joint CommissionUpdated October 2026
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Answer: C. 1447
In 24-hour time the hours after noon keep counting from 12, so add 12 to any hour from 1 PM on: 2:47 PM becomes 14:47, written 1447 with no colon and no AM or PM. Laboratories require the date and time of collection on every tube, and 24-hour time removes AM/PM mix-ups on timed draws.
Why the other choices are wrong
- A. 0247 is 2:47 in the morning, 12 hours off.
- B. 1247 is 12:47 PM, two hours early.
- D. The lab asked for 24-hour time, which has no AM or PM. That is the point of the format.
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Answer: A. Label them at the bedside before leaving the room
The Joint Commission's patient identification goal (NPSG.01.01.01) requires containers used for blood and other specimens to be labeled in the presence of the patient, and laboratory policies add that it is done immediately after collection, before leaving the room. Labeling anywhere else opens a window in which one patient's label can go on another patient's blood.
Why the other choices are wrong
- B. No time window makes labeling away from the patient acceptable.
- C. Someone who did not draw the blood cannot confirm whose blood is in the tube.
- D. Unlabeled tubes left in a room can be mixed up with another patient's specimens.
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Answer: D. Barcode labels applied at the draw, in the patient's presence
A CDC-funded Laboratory Medicine Best Practices systematic review (Snyder et al., 2012) found that barcoding systems for specimen labeling effectively reduced patient specimen identification errors; all 17 studies it included favored barcoding. Applying the label at the collection site, in the patient's presence, leaves no gap in which tubes can be switched.
Why the other choices are wrong
- A. Batch labeling away from the patient is how tubes get switched.
- B. A label needs two patient identifiers, not just the test name.
- C. A courier log tracks packages. It cannot show whose blood is in a tube.
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Answer: B. Total bilirubin
Bilirubin breaks down when exposed to light, which gives a falsely low result. Reference laboratories such as ARUP require bilirubin specimens to be protected from light during collection, storage and shipment and sent in an amber transport tube. Of the others, ammonia is chilled, a cold agglutinin is kept at body temperature and a PT/INR stays at room temperature.
Why the other choices are wrong
- A. Ammonia is chilled on ice. It is not the light-sensitive test.
- C. A cold agglutinin specimen is kept warm, at 37 °C, not shielded from light.
- D. A PT/INR is kept at room temperature. It is not light sensitive.
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Answer: C. Wrap the labeled tube in aluminum foil
Bilirubin is photolabile. Allina Health Laboratory's instructions say neonatal bilirubin goes in an amber microtube and, if none is available, the sample is protected from light by wrapping it in aluminum foil during transport. It stays shielded through processing and storage too.
Why the other choices are wrong
- A. A pocket is not a light-protection method the laboratory names. Use an amber tube or foil.
- B. Ice does not block light, and a clear bag lets light reach the tube.
- D. Light starts breaking bilirubin down right away. Direct sunlight can lower it by 50% within an hour.
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Answer: A. Place the tube in a slurry of crushed ice and water
Lactate keeps rising in the tube as the cells go on breaking down glucose, so the specimen is chilled at once and delivered immediately. Children's Minnesota's lactate procedure says to place the specimen in an ice slurry and deliver it to the lab for analysis within minutes. Ammonia is handled the same way: on ice immediately, then straight to the lab.
Why the other choices are wrong
- B. Waiting for a courier run delays a specimen that must be delivered and tested within minutes.
- C. Freezing whole blood ruptures red cells and hemolyzes the specimen.
- D. At room temperature the cells keep producing lactate, so the result rises falsely.
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Answer: D. Body temperature, 37 °C
Cryoglobulins are proteins that precipitate in the cold. If the blood cools before the serum is removed, they come out of solution with the clot and the result is falsely low or negative. Mayo Clinic Laboratories requires the specimen to stay at 37 °C until the serum is separated from the cells, with clotting at 37 °C and no refrigerated centrifuge.
Why the other choices are wrong
- A. Ice is the worst choice: cold makes cryoglobulins precipitate.
- B. Refrigeration also makes cryoglobulins precipitate before the serum is separated.
- C. Mayo accepts ambient temperature only for centrifuging, and only if necessary. Otherwise the specimen stays at 37 °C.
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Answer: B. Potassium
Cold storage of whole blood before separation inhibits glycolysis, so the cells' energy-dependent sodium-potassium pump stops holding potassium inside them. Potassium leaks out and the result rises falsely (Association for Clinical Biochemistry). Tubes for potassium are not chilled unless the test calls for it, and serum is separated from the cells within about 2 hours of collection.
Why the other choices are wrong
- A. Glucose falls, not rises, while serum sits on the cells.
- C. Sodium is not the analyte that cold storage falsely raises. Potassium leaking from the cells is the classic error.
- D. Cold storage does not release calcium from the cells. The classic cold-storage error is potassium.
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Answer: C. Red top (clot activator)
Plasma is the liquid from blood kept from clotting by an anticoagulant such as heparin, EDTA or citrate. Serum is what is left after the blood clots, so a tube with a clot activator, like the red top, gives serum. BD describes its heparin and PST tubes as tubes for plasma determinations and its serum tubes, coated with silica clot activator, as tubes for serum determinations.
Why the other choices are wrong
- A. Lithium heparin is an anticoagulant, so the green top gives plasma.
- B. EDTA is an anticoagulant, so the lavender top gives plasma.
- D. The light green PST contains lithium heparin and gives plasma. The gel only separates it from the cells.
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Answer: A. Within 2 hours
CLSI's handling standard calls for serum or plasma to be separated from the cells as soon as possible unless there is evidence that longer contact does not affect results, and 2 hours from collection is the widely used maximum. Some tests, such as ammonia and lactate, have much shorter limits. Left on the cells, glucose falls and potassium rises.
Why the other choices are wrong
- B. Eight hours of contact with the cells lets glucose fall and potassium rise for many tests.
- C. A full day on the cells changes many results. Longer limits apply to some separated or whole-blood specimens, not to unspun serum.
- D. Capping the tube does not stop the cells from metabolizing.
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Answer: D. Capped, at room temperature
CLSI H21 calls for citrated whole blood for coagulation testing to be transported and held at room temperature; a PT specimen kept that way can be tested up to 24 hours after collection. Chilling citrated whole blood can activate factor VII, cause loss of factor VIII and von Willebrand factor and damage platelets, so coagulation tubes are not iced or refrigerated.
Why the other choices are wrong
- A. Ice can cold-activate factor VII and change the PT.
- B. Refrigerating citrated whole blood has the same cold-activation problem as ice.
- C. Freezing whole blood ruptures the cells. Only separated plasma is ever frozen, and only when the lab requires it.
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Answer: B. At room temperature
BD's instructions for BACTEC bottles say to send inoculated bottles to the microbiology lab right away for the best recovery. If transport is unavoidably delayed, store them at room temperature and send them within 18 to 24 hours. Do not refrigerate them or incubate them above room temperature.
Why the other choices are wrong
- A. BD's instructions say not to refrigerate inoculated bottles.
- C. BD's instructions say not to incubate the bottles above room temperature before they reach the lab.
- D. Chilling the bottles is the same error as refrigerating them.
Where these answers come from
Each question was checked against the standard named in its explanation. The sources used in this set:
- 24-hour clock conversion; laboratory labeling requirements (date and time of collection on each label, e.g. UCSF Clinical Laboratories, OHSU)
- ARUP Laboratories test directory, bilirubin (protect from light; amber transport tube); Allina Health Laboratory, bilirubin (photolabile)
- Allina Health Laboratory, bilirubin specimen requirements (amber microtainer, or aluminum foil if none is available)
- Association for Clinical Biochemistry, analyte monograph: Potassium (cold storage before separation); CLSI PRE04-Ed1 (prompt separation)
- BD BACTEC blood culture bottle transport and storage instructions (as reproduced in IU Health Blood Culture Collection Guidelines)
- BD Vacutainer heparin, PST and serum tube product information (plasma vs serum determinations)
- CDC Laboratory Medicine Best Practices: Snyder et al., barcoding systematic review and meta-analysis (Clin Biochem, 2012); The Joint Commission NPSG.01.01.01
- CLSI H21-Ed6 (collection, transport and processing of blood specimens for plasma-based coagulation assays)
- CLSI PRE04-Ed1 (separation of serum or plasma from cells; 2-hour working maximum)
- Children's Minnesota laboratory, lactate (place in an ice slurry, deliver immediately); Rady Children's Hospital laboratory, ammonia (place on ice immediately)
- Mayo Clinic Laboratories, Cryoglobulin, Serum (CRY_S) specimen requirements
- The Joint Commission NPSG.01.01.01 (label specimen containers in the presence of the patient); laboratory labeling policies
More free practice tests
Every set has different questions, each with an explanation and your score by domain. No account needed.
By certification exam
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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) | ASCP PBT practice exam |
| 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
Clinical References
- CLSI PRE02-Ed8 — Collection of Diagnostic Venous Blood Specimens (8th ed., 2025)
- 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