Capillary Collection Quiz: 12 Free Heel and Fingerstick Questions
Twelve questions on skin puncture: where on the heel to stick an infant and where never to, who should not have a fingerstick, why the alcohol must dry, why squeezing ruins a sample, which microtube fills first, and how to collect a newborn screening card. Each answer is explained, wrong options included, with the source it was checked against. Review the capillary collection 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: B. Bone, nerves and tendons lie close to the skin there
WHO's capillary sampling guidance limits heel punctures to the medial or lateral plantar surface and says punctures must not be made on the posterior curvature or the central area of the foot, where they can injure nerves, tendons and cartilage. The heel bone also lies close to the skin there, and a puncture that reaches bone can cause osteomyelitis.
Why the other choices are wrong
- A. Skin thickness is not the reason. The risk is injury to what lies beneath.
- C. Clotting speed is not the concern. The posterior curvature is avoided to protect bone, nerves and tendons.
- D. How the foot is held does not change the rule. The site itself is unsafe.
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Answer: D. Avoid skin puncture and ask about a venous draw
Skin puncture depends on good blood flow to the skin. Akron Children's capillary puncture procedure states that capillary puncture should not be used on patients who are extremely dehydrated or have poor peripheral circulation. The patient needs a venipuncture, arranged with the ordering provider under facility policy.
Why the other choices are wrong
- A. Squeezing forces tissue fluid into the drop and can hemolyze it.
- B. WHO advises avoiding the thumb, which is often callused.
- C. A deeper puncture risks injury and does not fix poor blood flow.
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Answer: A. The blood cultures
Blood cultures need far more blood than a skin puncture yields. Sarstedt's blood collection guideline notes that capillary collection gives very small volumes and is not suited to analyses needing more than about 1 mL, such as blood cultures, which are collected by venipuncture. A CBC can be run on capillary blood in an EDTA microtube.
Why the other choices are wrong
- B. A CBC can be collected in an EDTA microtube by skin puncture.
- C. Blood cultures need venous volume. A fingerstick cannot fill culture bottles.
- D. The CBC is acceptable by skin puncture. Only the cultures need a venipuncture.
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Answer: C. Use a new lancet at a different site
Western Australia's Child and Adolescent Health Service capillary procedure, drawing on WHO, says not to puncture the skin more than once with the same lancet or use one puncture site more than once, because this can cause bacterial contamination and infection. If blood does not flow freely, make a new puncture with a new lancet at a different site rather than squeezing.
Why the other choices are wrong
- A. Reusing a lancet or a site risks bacterial contamination and infection.
- B. Even with a new lancet, reusing the same site risks infection.
- D. The center of the heel is never punctured. Bone and nerves lie close to the skin there.
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Answer: B. Dilute or hemolyze the sample
WHO directs that the alcohol be allowed to air-dry before the puncture. Western Australia's capillary procedure, citing WHO, explains that puncturing before the skin is dry can dilute or hemolyze the sample and adversely affect the results. Wiping away the first drop also removes residual alcohol.
Why the other choices are wrong
- A. Puncturing through wet alcohol harms the sample. The site is allowed to dry first.
- C. Alcohol does not clot the drop. It can dilute or hemolyze it.
- D. Alcohol does not raise the platelet count. The concern is dilution and hemolysis.
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Answer: D. It mixes in tissue fluid and hemolyzes cells
Sarstedt's collection guideline says to avoid pressure or 'milking' of the puncture site to prevent hemolysis and contamination of the sample with tissue fluid, and WHO tells collectors to avoid squeezing the finger too tightly. Gentle, intermittent pressure is acceptable. If blood still does not flow, make a new puncture.
Why the other choices are wrong
- A. Squeezing does not close the wound. The problem is what it does to the sample.
- B. Squeezing does not raise glucose. Dilution with tissue fluid is the concern.
- C. Air in the tube is a filling problem, not the effect of squeezing.
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Answer: A. A falsely low platelet count
In capillary collection the EDTA tube is filled before other additive and serum tubes (CLSI GP42-Ed7: blood gas, EDTA, other additives, serum; WHO: hematology specimens first), because the blood begins to clot and platelets clump at the puncture site as soon as it flows. Filling the EDTA tube last gives platelets time to clump, and clumped platelets are not counted, so the count reads falsely low.
Why the other choices are wrong
- B. Delayed filling does not concentrate hemoglobin. Platelets are the cells that clump.
- C. A delay does not add red cells. Platelet clumping is the problem.
- D. Capillary collection has its own order, and the EDTA tube comes first.
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Answer: C. To 'arterialize' the blood by increasing flow
Warming the site increases arterial blood flow to it up to sevenfold, and at no more than 42 °C it will not burn the skin (CLSI GP42-Ed7). The extra arterial flow 'arterializes' the capillary blood so its gas values compare acceptably with arterial blood.
Why the other choices are wrong
- A. Warming does not disinfect. The site is still cleaned with antiseptic.
- B. Comfort is not the purpose. Warming is done to increase arterial flow.
- D. Warming increases blood flow. It is not used to speed clotting.
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Answer: B. Between 24 and 48 hours of age
Newborn screening programs such as Minnesota's state that blood spots are best collected between 24 and 48 hours of age. Specimens collected earlier cannot be fully interpreted and must be repeated, and later collection may not give results before a serious disorder causes symptoms. For this baby, that window runs from 0600 Tuesday to 0600 Wednesday.
Why the other choices are wrong
- A. Specimens taken too early cannot be fully interpreted and are marked unsatisfactory.
- C. Two weeks is too late. Some disorders cause symptoms before the results would be back.
- D. Six months is far too late for screening meant to find disorders before symptoms start.
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Answer: D. Hand oils and other material can contaminate the paper
Minnesota's newborn screening program tells collectors to avoid touching the area within the circles before, during and after collection, because oils and other materials from the hands might affect or contaminate the card or the specimen. Hold the card by its edges.
Why the other choices are wrong
- A. Color change is not the concern. Any material from hands or gloves can contaminate the specimen.
- B. Touching does not change how much blood the paper absorbs. The concern is contamination.
- C. Gloves do not make it acceptable. Anything touching the circles can contaminate them.
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Answer: A. Let a large drop soak in from one side
Minnesota's program instructs: in one step, let the blood soak through the filter paper and fill the circle, and do not press the paper directly against the baby's heel. Blood goes on one side of the paper only, and drops are not layered, because each circle must hold a set volume of blood. Western Australia's procedure likewise says contact between the puncture site and the card must be avoided.
Why the other choices are wrong
- B. Pressing the paper to the heel is the error. More pressure makes it worse.
- C. Blood is applied to one side only, never both.
- D. Layering drops puts the wrong volume in the circle and can make the test inaccurate.
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Answer: C. Collect a screening specimen before the transfusion
The Texas newborn screening laboratory says to collect the first newborn screen before a transfusion, even if the newborn is not yet 24 hours old. Transfusions, even small ones, can affect the hemoglobinopathy, galactosemia and DNA tests and may invalidate the results. Further screens follow on the program's schedule.
Why the other choices are wrong
- A. Waiting until after the transfusion lets donor blood affect the hemoglobinopathy, galactosemia and DNA tests.
- B. Transfused babies are screened. The first screen is simply collected before the transfusion.
- D. Blood drawn during the transfusion already contains donor cells.
Where these answers come from
Each question was checked against the standard named in its explanation. The sources used in this set:
- Akron Children's Hospital laboratory, Performing a Capillary Puncture (not for extreme dehydration or poor peripheral circulation); WHO capillary sampling job aid
- CLSI GP42-Ed7 (as summarized in MLO, 'Best practices in capillary blood collection'); Sarstedt, Blood Collection in Practice (warming arterializes capillary blood)
- CLSI GP42-Ed7 capillary order of collection (as summarized in MLO, 'Best practices in capillary blood collection'); WHO capillary sampling job aid
- Child and Adolescent Health Service (Western Australia), Capillary Blood Sampling (Heel and Finger Prick), 2025, citing WHO Guidelines on Drawing Blood
- Minnesota Department of Health, Newborn Screening blood spot collection (best collected at 24 to 48 hours of age)
- Minnesota Department of Health, Newborn Screening blood spot collection (do not touch the circles); CLSI NBS01
- Minnesota Department of Health, Newborn Screening blood spot collection; Child and Adolescent Health Service (Western Australia), Capillary Blood Sampling; CLSI NBS01
- Sarstedt, Blood Collection in Practice (avoid milking: hemolysis, tissue fluid); WHO capillary sampling job aid
- Sarstedt, Blood Collection in Practice (capillary blood not suited to volumes over 1 mL, e.g. blood cultures)
- Texas DSHS Newborn Screening Laboratory, Spot Focus: Collect the first newborn screen before a transfusion (2021)
- WHO Guidelines on Drawing Blood (2010), paediatric and neonatal sampling; Akron Children's Hospital capillary puncture procedure; CLSI GP42-Ed7
- WHO capillary sampling job aid (allow alcohol to air-dry); Child and Adolescent Health Service (Western Australia), Capillary Blood Sampling
More free practice tests
Every set has different questions, each with an explanation and your score by domain. No account needed.
By certification exam
General phlebotomy practice tests
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