NHA Phlebotomy Technician (CPT) — All Questions

A phlebotomist is asked to collect blood from a patient who is having a seizure at the moment of arrival. What is the correct action?

• a.Draw quickly from the arm that is moving least, because a stat order cannot be delayed for any reason
• b.Do not attempt the draw; get help, protect the patient from injury and return when it is safe✓
• c.Hold the patient's arm firmly still with the help of a colleague and complete the collection
• d.Place a padded tongue blade between the teeth first, then decide whether the draw can proceed

A needle must never be introduced into a moving limb, and no laboratory result is worth a nerve injury or a needlestick. The phlebotomist summons help, keeps the patient from striking nearby objects and does not restrain them, then returns once the seizure has ended and the nurse confirms it is safe. Putting anything into the mouth of a seizing patient is an outdated practice that causes injury.

Which area of a newborn's foot is an acceptable heel puncture site?

• a.The posterior curvature of the heel, where the skin is thickest and the stick hurts least
• b.The medial or lateral plantar surface of the heel, away from the curve of the bone✓
• c.The centre of the arch, because it is the fleshiest part of the sole
• d.Any part of the sole, provided the lancet used is a retractable safety model

The plantar surface medial or lateral to an imaginary line drawn back from the great toe and from between the fourth and fifth toes keeps the lancet away from the calcaneus. The posterior curvature sits directly over that bone, and the arch overlies nerves, tendons and arteries. A safety lancet controls depth but does not make an unsafe location safe.CLSI GP42

What is the maximum penetration depth accepted for a heel puncture on a newborn, and why does it matter?

• a.Five millimetres, which is needed to reach the capillary bed under an infant's thick plantar skin
• b.Whatever depth the device delivers, since incision devices are pre-set by the manufacturer
• c.Two millimetres, because a deeper stick can reach the bone and cause osteomyelitis✓
• d.One centimetre, matching the depth used for an adult fingerstick

The accepted ceiling is 2.0 millimetres. The calcaneus of a newborn lies close beneath the plantar skin, and a lancet that reaches it can cause bone infection, cartilage damage and scarring. Devices are indeed pre-set, but the phlebotomist still has to choose one made for a newborn heel rather than one made for an adult finger, so the depth limit is the reason the choice matters.CLSI GP42

Which finger and which part of it should be used for an adult capillary puncture?

• a.The fleshy pad of the third or fourth finger, slightly off centre and across the fingerprint lines✓
• b.The thumb, because it has the largest blood supply of any digit and therefore bleeds the most freely
• c.The very tip of the index finger, which is the easiest point to reach with a lancet
• d.The side of the fifth finger, where the tissue over the bone is thinnest

The middle or ring finger of the non-dominant hand is punctured on the palmar side of the last joint, just to the side of centre, and the cut is made across rather than along the fingerprint lines so the drop forms instead of running into a groove. The index finger and thumb are more callused and more used, the little finger has too little tissue over bone, and the very tip and the sides are more painful and poorly perfused.CLSI GP42

Why is the first drop of blood wiped away after a capillary puncture?

• a.Because it is the coldest blood in the finger and would give a falsely low glucose reading
• b.Because it has already begun to clot and would block the microtube before it could be filled
• c.Because wiping it is the only way to remove the alcohol from the puncture
• d.Because it is diluted with tissue fluid, and residual alcohol may be mixed into it as well✓

The puncture releases interstitial fluid along with blood, and any alcohol that has not fully evaporated is carried in the same first drop. Both dilute the specimen and can hemolyze it, so that drop is wiped away with clean gauze and collection begins with the second. Blood does not clot that quickly, and temperature has no bearing on it. Letting the alcohol dry before puncturing is a separate and equally necessary step.CLSI GP42

A capillary specimen is filling slowly, so the phlebotomist squeezes the finger repeatedly. What is the consequence?

• a.The specimen fills faster with no effect on the result, which is why the technique is widely taught
• b.Tissue fluid and hemolysis contaminate the specimen and distort potassium and cell counts✓
• c.The specimen clots faster because squeezing activates the platelets in the puncture wound
• d.Nothing changes, because the microtube additive corrects for any dilution that occurs

Milking forces interstitial fluid into the sample and ruptures red cells, which raises potassium and lowers cell counts and can make a normal potassium look dangerously high. The remedy for slow flow is to warm the site beforehand, hold the hand below heart level and apply gentle intermittent pressure well behind the puncture, or to repuncture at a new site. No additive corrects contamination that is already in the tube.CLSI GP42

In what order are capillary microcollection containers filled when several are required?

• a.Serum first, then the additive tubes, mirroring the venous order of draw exactly as written
• b.The largest container first, so the best quality blood goes where the most volume is needed
• c.Blood gas specimens first, then EDTA, then other additive tubes, then serum✓
• d.Any order, because a capillary sample is mixed continuously as it drips into each container

The capillary order differs from the venous one. EDTA comes early, immediately after any blood gas specimen, because platelets begin to aggregate at the puncture site and a delayed EDTA tube gives a falsely low platelet count. Serum containers come last. Container size does not determine the sequence, and the order is not optional because the changes happen in the wound, not in the tube.CLSI GP42

How does capillary blood differ chemically from venous blood drawn at the same moment?

• a.Glucose runs higher, while potassium, calcium and total protein all run lower✓
• b.Every analyte is identical, because capillary blood is simply venous blood collected from a smaller vessel
• c.Glucose runs lower and potassium runs higher, so a capillary potassium may be reported as critical
• d.Only the cell counts differ; all of the chemistry values are the same in both specimens

A skin puncture yields a mixture of arterial, venous and capillary blood together with interstitial and intracellular fluid, and the arterial contribution raises glucose while potassium, calcium and total protein come out lower than a venous specimen. The differences are real and predictable, which is why a laboratory records the source and why capillary and venous results should not be compared as if identical.

A newborn screening card is being collected by heel stick. Which technique produces an acceptable specimen?

• a.Touch the card repeatedly to the heel until each printed circle looks evenly and completely coloured
• b.Layer several small drops on top of one another until it is saturated
• c.Fill the circles from the back of the card, since the printed side is treated and repels blood
• d.Let one large drop soak through and fill each circle, applying blood to one side only✓

Each circle is filled with a single large free-falling drop applied to one side of the filter paper and allowed to soak through, then the card is air dried horizontally at room temperature away from heat and sunlight. Repeated touching, layering and applying blood to both sides all produce clotted, layered or saturated spots that the screening laboratory rejects, which delays the detection of a treatable metabolic disorder.

Why should povidone iodine not be used to prepare the skin for a capillary puncture?

• a.It stains the skin, which makes it impossible to see the puncture site clearly enough to collect
• b.Iodine carried into the sample falsely raises potassium, phosphorus and uric acid✓
• c.It takes far longer to dry than alcohol, and the collection cannot begin until it has dried
• d.It is reserved for blood cultures, and using it elsewhere wastes an expensive supply

Iodine residue picked up in a skin puncture specimen interferes with several chemistry measurements and can push a result out of range on its own, so seventy percent isopropyl alcohol is used for routine capillary work and allowed to dry completely. Drying time and cost are real considerations but they are not the reason, and blood cultures are one of several appropriate uses for iodine.

Why is a fingerstick avoided in an infant under one year of age?

• a.Infants under one year have no measurable capillary circulation in the fingers at all
• b.The fingers of an infant cannot be warmed enough to produce a usable flow of blood
• c.There is too little tissue between the skin and the bone, so the lancet can injure it✓
• d.The volume obtainable from an infant finger is always far greater than a microtube can hold

The distance from skin to bone in an infant's finger is small enough that a lancet set for an adult finger can reach the phalanx, so the heel is used instead until the child is walking and the plantar tissue thickens. Infants certainly have capillary circulation and their fingers can be warmed. Yield is a limitation of the site, not an overflow problem.

A neonatal bilirubin is collected by heel stick into a microtube. What handling does the specimen require?

• a.Warm the microtube to body temperature and deliver it to the laboratory within four hours
• b.Freeze the specimen at once, because bilirubin breaks down rapidly at any warmer temperature
• c.Add a drop of saline to the microtube so the small volume can be pipetted by the analyser
• d.Protect it from light and deliver it promptly, using an amber tube or a foil wrap✓

Bilirubin is degraded by light, and a specimen left on a windowsill or under a phototherapy lamp can lose a clinically important amount within an hour. That falsely low result may mask a rising bilirubin in a newborn at risk of kernicterus. The tube is shielded and sent straight to the laboratory. Warming, freezing and diluting a specimen are not part of bilirubin handling.

Which statement about drawing blood from a premature or low birth weight infant is correct?

• a.The total volume removed must be tracked, because repeated draws can cause iatrogenic anemia✓
• b.Volume is not a concern, since an infant regenerates blood a great deal faster than an adult does
• c.The infant should be drawn from a single site each time so that only one area ever bruises
• d.The heel may be punctured as many times as needed provided a new lancet is used each time

A small infant has a very small circulating volume, so millilitres removed for testing matter and neonatal units set cumulative limits over a defined period. Sites are rotated rather than reused, because repeated punctures in one place cause scarring and infection. A fresh lancet is required every time but that does not license unlimited punctures.

A four-year-old is frightened and asks the phlebotomist whether the blood draw will hurt. What is the best reply?

• a.Reassure the child that it will not hurt at all, so that she relaxes and holds still for the needle
• b.Say honestly that it will pinch for a moment, and give her something simple to do during it✓
• c.Explain the venipuncture procedure step by step in the same detail used for an adult patient
• d.Tell her that children who cry during a blood draw have to be held down by two people

Children cope better with a short honest description and a small task, such as counting or holding a parent's hand, than with a promise that is broken the moment the needle enters and destroys their trust for every future draw. Adult-level detail overwhelms a preschooler, and threatening restraint is coercive and increases distress rather than reducing it.

Why are adhesive bandages generally avoided on children under two years old after a blood collection?

• a.Because the adhesive prevents the puncture from clotting and the child will keep bleeding
• b.Because a bandage hides the site from the parent afterwards
• c.They can be pulled off and swallowed, and the adhesive tears very delicate skin✓
• d.Because a toddler's skin is too oily for any adhesive dressing to stay in place at all

A small child will pick at a bandage, and a loose one is a choking hazard, while the adhesive itself can strip the thin skin of an infant. Pressure is held until bleeding stops and gauze secured with a self-adherent wrap is used if a covering is needed. Adhesive does not stop a clot forming, and hiding the site is a minor issue next to aspiration.

An 82-year-old patient has thin, papery skin and prominent but fragile veins. Which set of adjustments is appropriate?

• a.Apply the tourniquet more tightly than usual so the fragile vein is held firmly in position
• b.Use the largest tube available so the draw finishes before the vein has time to collapse
• c.Slap the skin over the vein to raise it, then insert quickly at a steep angle
• d.Use a winged set and small tubes, anchor gently, and hold pressure for longer afterwards✓

Fragile veins tolerate less vacuum and fragile skin tolerates less traction, so a winged set with small volume tubes, gentle anchoring and unhurried entry protect both. Pressure is held longer because older patients bleed longer, particularly on aspirin or an anticoagulant. A tighter tourniquet, a larger tube and slapping the skin all increase the risk of hematoma and skin tearing.

How should a phlebotomist secure the puncture site on an older patient whose skin tears easily?

• a.Hold gauze with pressure, then wrap it with a self-adherent bandage instead of adhesive tape✓
• b.Apply a strong adhesive tape and warn the patient to pull it off quickly in a single movement
• c.Skip any covering, since older skin heals fastest when the site is left completely open
• d.Use two adhesive bandages crossed over one another so the gauze cannot slip out of place

Self-adherent wrap sticks to itself rather than to skin, so it holds gauze in place without stripping tissue when it comes off. Adhesive tape on paper-thin skin can tear it and open a wound that heals slowly. Leaving the site uncovered risks bleeding restarting, and doubling adhesives multiplies the very problem being avoided.

A phlebotomist is drawing blood from a patient with advanced dementia who does not respond to questions. How should identification be handled?

• a.Accept the room number and the name written on the door as the two required identifiers
• b.Verify the wristband against the requisition and have a caregiver or nurse confirm the identity✓
• c.Ask the patient to state her own name and accept whatever answer she gives without any further checking
• d.Draw the specimen first and confirm the identity with the nurse before the label is applied

A patient who cannot reliably state her own name is identified from the wristband checked against the requisition, with a nurse, caregiver or family member confirming. Room numbers and door signs are not patient identifiers and change constantly. Accepting an unreliable verbal answer, or labelling after the fact, are the two routes to a wrong-patient result and a wrong transfusion.

Which microhematocrit tube should be used to fill directly from a capillary puncture with no anticoagulant tube in between?

• a.The tube with a blue band, which contains no additive at all
• b.Either tube, because the sample spins down to the same packed cell volume in both cases
• c.The tube with a red band, which is coated on the inside with heparin✓
• d.Neither, because a hematocrit can only be run from a venous lavender tube

Blood taken straight from a skin puncture has nothing to stop it clotting, so the heparinised tube, marked with a red band, is the correct choice. The blue banded plain tube is used when the blood has already been anticoagulated, typically from a lavender EDTA tube. A clotted specimen gives a meaningless packed cell volume, and hematocrit is routinely performed on capillary blood.

A parent asks to hold her two-year-old during a venipuncture. What is the usual practice?

• a.Parents are excluded from the room so that their anxiety cannot transfer to the child
• b.The parent may stay only if she agrees to hold the arm still while the needle is inserted
• c.The child must be swaddled alone on a table, because any holding contaminates the site
• d.A supportive hold with the parent present is encouraged where facility policy allows it✓

Comfort positioning, with the child upright on the parent's lap and the arm supported, reduces distress and struggling and is widely encouraged where policy permits. Excluding a parent is not the norm, and asking a parent to restrain a child places them in the role the child will remember. Being held does not contaminate a site that is prepared and kept clean.

How long should a heel warming device be applied before a newborn capillary collection, and at what temperature?

• a.Three to five minutes at a temperature no higher than about 42 degrees Celsius✓
• b.Fifteen to twenty minutes at whatever temperature the nursery warmer happens to be set to
• c.Thirty seconds at 50 degrees Celsius, which opens the capillaries fastest of all the options
• d.Warming is not used on newborns because their circulation is already at its maximum

Three to five minutes of gentle warming at a ceiling of about 42 degrees Celsius increases blood flow to the heel several fold and makes a single puncture sufficient. Hotter packs scald infant skin, which is thinner than an adult's. A quarter of an hour is unnecessary and leaves the infant handled longer than needed, and warming is a standard part of neonatal capillary collection.

Which specimen should not be collected by skin puncture?

• a.A hemoglobin and hematocrit on a patient whose veins are exhausted from repeated draws
• b.A set of blood cultures on a patient with a suspected bloodstream infection✓
• c.A point of care glucose on a patient in an outpatient diabetes clinic
• d.A newborn screening card on a two-day-old infant in the nursery

Blood cultures need a volume that a skin puncture cannot supply, and the puncture site cannot be kept sterile through a capillary collection, so contamination and false negatives follow. Point of care glucose, newborn screening and small volume hematology are all standard capillary work. Tests requiring plasma or serum in quantity, and coagulation studies, are also unsuitable.

A capillary glucose is collected from a patient's fingertip immediately after the patient has eaten an orange without washing their hands. What is the risk?

• a.Citric acid on the skin destroys the glucose in the sample and the meter will read far too low
• b.There is no risk, because the meter measures only what it draws in
• c.Sugar residue on the finger can be picked up in the drop and give a falsely high glucose✓
• d.The fruit acid corrodes the test strip so the meter displays an error rather than a number

Contamination from food, juice, lotion or an alcohol-based hand product on the fingertip is a documented cause of falsely high point of care glucose readings, and a spuriously high result can prompt an insulin dose the patient does not need. The site is washed with soap and water and dried before the puncture. Meters measure glucose in whole blood, not only inside cells.

A phlebotomist runs the low and high control solutions on a point of care glucose meter and the high control falls outside its range. What is the correct action?

• a.Do not report patient results from that meter; troubleshoot and repeat before any patient is tested✓
• b.Report the patient results but add a comment noting that the high control was out of range that morning
• c.Run only the low control from then on, since it was the one that gave an acceptable result
• d.Test the patient anyway and repeat the control afterwards to see whether it corrects itself

A failed control means the instrument has not demonstrated that it can measure accurately, so patient testing stops until the cause is found, whether it is an expired strip lot, a storage problem, a coding error or the meter itself. Reporting with a comment, dropping a control level or testing first and checking later all put a patient result of unknown accuracy into the record.

A patient at an outpatient clinic needs a hemoglobin A1c and has excellent antecubital veins. Why is a venous draw usually preferred over a capillary one here?

• a.Capillary blood cannot be used for a hemoglobin A1c under any circumstances at all
• b.A venous specimen gives adequate volume and avoids the tissue fluid a skin puncture adds✓
• c.Capillary punctures are more painful than venipuncture, so patients refuse them more often
• d.A capillary sample would clot immediately because no microtube contains a suitable additive

Where a good vein is available, a venous EDTA tube supplies ample well mixed whole blood without the interstitial fluid dilution and hemolysis risk that come with a skin puncture. Capillary A1c testing does exist on waived devices and is used where venous access is difficult, so it is not forbidden. Microtubes with EDTA are readily available, and pain is a poor basis for the choice.

A lancet has been used for a fingerstick and the collection is complete. How is it discarded?

• a.Rinse it under running water and place it in the regular waste after the blood is removed
• b.Retract the blade, then set it on the tray until the whole round of patients is finished
• c.Place it in a red biohazard bag along with the used gauze and the wrappers
• d.Drop it into a sharps container at the point of use, without recapping or resheathing✓

Any device that has punctured skin goes straight into a puncture resistant sharps container at the place it was used, not into a bag, a tray or the ordinary trash. A biohazard bag holds soft regulated waste and offers no protection against a blade. Rinsing a contaminated sharp creates a splash hazard, and carrying used sharps around is how injuries to housekeeping staff happen.

Which single factor has the greatest influence on whether a blood culture will detect an organism that is present?

• a.The brand of bottle used, because each manufacturer's broth recovers a different set of organisms
• b.The volume of blood placed in each bottle before it is sent for incubation✓
• c.Whether the aerobic bottle or the anaerobic bottle is inoculated first from the collection set
• d.The gauge of the needle, since a wider bore protects the organisms from mechanical damage

Bacteria are present in very small numbers in adult bloodstream infections, so recovery rises with the amount of blood cultured, and an underfilled bottle is a leading cause of a false negative that leaves a septic patient on the wrong antibiotic. Adult bottles are typically filled with eight to ten millilitres each; follow the manufacturer's stated volume. Order of inoculation and needle gauge matter far less.CLSI M47

How should the rubber septum on the top of a blood culture bottle be prepared before the blood is added?

• a.Scrub it with povidone iodine and leave the iodine in place so it keeps working during transport
• b.Wipe it with seventy percent alcohol and let it dry before the needle goes through✓
• c.Remove the plastic flip cap and add the blood at once, since the septum beneath is already sterile
• d.Flame the septum briefly with a lighter to sterilise the surface before the needle passes through

The flip cap keeps the septum clean but does not sterilise it, so the exposed rubber is disinfected with alcohol and allowed to dry before the needle goes through. Iodine is used on the patient's skin rather than on the bottle, because iodine residue can degrade the septum and is unnecessary there. Flaming a bottle top is not an accepted practice in any modern collection standard.CLSI M47

A blood culture set is being collected with a winged blood collection set. Which bottle is inoculated first and why?

• a.The anaerobic bottle, so that no oxygen at all can reach the organisms that need an oxygen-free space
• b.Whichever bottle is nearest, because the two bottles contain exactly the same broth and additive
• c.The anaerobic bottle, because it is the one that has to be filled to the line for the culture to count
• d.The aerobic bottle, because the air in the tubing enters the first bottle attached✓

A winged set holds a small volume of air in its tubing, and that air goes into whichever bottle is attached first. Sending it into the aerobic bottle is harmless, while sending it into the anaerobic bottle works against the very condition that bottle exists to create. When a syringe is used the situation differs, so follow the manufacturer's and the facility's stated sequence.CLSI M47

Why are two blood culture sets usually drawn from two separate venipuncture sites?

• a.Because an organism growing in only one set points toward skin contamination rather than infection✓
• b.Because a single venipuncture site cannot yield enough blood to fill two bottles in an adult patient
• c.Because the laboratory needs a duplicate specimen in case the first one is dropped or mislabelled
• d.Because facility policy requires that every microbiology specimen be collected twice for accuracy

Two sets from two sites let the laboratory interpret what grows. A skin organism such as a coagulase-negative staphylococcus appearing in one set of four bottles usually reflects contamination introduced at that puncture, while the same organism in both sets suggests a real bloodstream infection. Volume, breakage and blanket duplication policies are not the reason.CLSI M47

When does the timing clock start for the specimens of a two-hour glucose tolerance test?

• a.When the fasting specimen is collected, since that is the first sample in the whole series
• b.When the patient arrives at the laboratory and is registered for the appointment that morning
• c.When the patient swallows the last of the glucose solution she was given✓
• d.When the patient begins to drink, because the first mouthful is already being absorbed

The timed specimens are counted from the moment the patient swallows the last of the glucose load, which should be consumed within about five minutes. Starting the clock at the fasting draw or at registration shifts every subsequent specimen, and a glucose reported at the wrong interval can create or hide a diagnosis of diabetes. Exact collection times are documented on each tube.

During a glucose tolerance test the patient asks whether she may step outside for a cigarette between draws. What should the phlebotomist say?

• a.No, smoking is not permitted during the test and she should stay in the area✓
• b.Yes, provided she returns before the next timed specimen is scheduled to be collected
• c.Yes, because nicotine has no measurable effect on any blood glucose measurement at all
• d.Yes, but only if she agrees to have the remaining specimens collected by capillary puncture

Smoking stimulates the release of glucose from stores and can raise the measured value, so it is prohibted for the duration along with eating, drinking anything other than water and chewing gum. The patient also stays where staff can watch for hypoglycemia or fainting. Nicotine is not inert, and switching to capillary collection would change the specimen type mid-test.

A provider orders a trough level for an antibiotic. When is the specimen collected?

• a.Thirty minutes after the dose finishes infusing, when the drug is most evenly distributed
• b.At any convenient point in the dosing interval, as long as the exact time drawn is recorded
• c.Immediately before the next scheduled dose is due to be given to the patient✓
• d.Exactly halfway between two doses, which is the average concentration over the interval

A trough is the lowest concentration in the dosing interval and is measured just before the next dose, which is what tells the prescriber whether the drug stays above the level needed to work. A peak is drawn after the dose at a time that depends on the drug and route. Drawing at a random or midpoint time produces a number that cannot be interpreted, and the exact draw time is always recorded.

Which piece of information must be documented with a therapeutic drug monitoring specimen for the result to be interpretable?

• a.The patient's weight and height, so the laboratory can calculate the expected concentration
• b.The exact time the specimen was drawn and the time of the last dose✓
• c.The route by which the patient prefers to receive the medication in future dosing
• d.The name of the phlebotomist who collected it, which is what makes the result reportable

A drug level means nothing without its position in the dosing interval, so both the collection time and the time the last dose was given are recorded. Without them a prescriber cannot tell a safe trough from a toxic peak. The collector's identity is required on any specimen for traceability but it is not what makes a drug level interpretable, and the laboratory does not calculate expected concentrations from body size.

A blood alcohol level is ordered as part of a legal proceeding. How is the skin prepared?

• a.With seventy percent isopropyl alcohol, which is the routine antiseptic for every venipuncture
• b.With an alcohol-based chlorhexidine scrub, the same preparation used for blood cultures
• c.With no antiseptic at all, because any preparation would invalidate a legal specimen
• d.With a non-alcohol antiseptic such as aqueous benzalkonium chloride or soap and water✓

Alcohol-containing preparations, including alcohol-based chlorhexidine, can be challenged as a source of the measured alcohol, so a non-alcohol antiseptic is used and the choice is documented. The site is still disinfected; leaving it unprepared would create an infection risk and would not help the case. The tube is filled completely and handled under chain of custody.

What does a chain of custody record establish for a forensic specimen?

• a.That the laboratory used an instrument that was calibrated on the morning the specimen was analysed
• b.That the patient consented in writing to the test and understood what it would be used for
• c.That the specimen was collected within the window of time the court order specified
• d.Who had the specimen at every moment from collection to analysis, with signatures and times✓

The chain of custody is an unbroken written record of possession. Each person who handles the sealed specimen signs and dates it, so it can be shown in court that the sample tested is the sample taken and that no one had an unrecorded opportunity to alter it. Consent, calibration and collection timing are all real requirements but each is documented somewhere else.

A patient with hereditary hemochromatosis is scheduled for therapeutic phlebotomy. What is the purpose of the procedure?

• a.To remove a measured volume of blood in order to reduce the patient's iron burden✓
• b.To collect a diagnostic specimen large enough for the full panel of iron studies to be repeated
• c.To obtain a unit of blood that will be transfused into another patient on the same day
• d.To replace the patient's plasma with donor plasma while returning the red cells to the patient

Therapeutic phlebotomy removes red cells, and with them iron, on a physician's order, typically about five hundred millilitres at a session, and it is also used in polycythemia vera to reduce red cell mass. It is treatment, not diagnosis. The blood is generally discarded rather than transfused, and exchanging plasma is a different procedure performed with an apheresis machine.

Which needle gauge is typically used to collect a unit of blood from a volunteer donor?

• a.A 23 gauge, the same as the winged set used for a difficult outpatient venipuncture
• b.A 21 gauge, matching the routine choice for a diagnostic evacuated tube collection
• c.A 16 to 18 gauge, because the wide lumen protects the red cells in a large collection✓
• d.A 25 gauge, since a slower fill gives the anticoagulant in the bag more time to mix in

Donor collection uses a large bore needle so that roughly a pint of blood flows quickly through a wide lumen without shearing the red cells, which preserves the unit for transfusion. A diagnostic gauge would take far too long and would hemolyze the product. A 25 gauge is not used for whole blood collection at all because of the damage it causes.

Which specimen must be kept at body temperature from collection until it reaches the laboratory?

• a.A plasma ammonia, which is transported in an ice slurry to slow the breakdown of the analyte
• b.A serum bilirubin, which is wrapped in foil so that light cannot degrade the pigment in transit
• c.A prothrombin time, which is transported at ordinary room temperature within the stated window
• d.A cold agglutinin titre, which must be kept at 37 degrees Celsius so the antibody stays free✓

Cold agglutinins bind to red cells as the specimen cools, so a sample allowed to reach room temperature loses antibody from the serum and the titre is reported falsely low. The tube is prewarmed and carried in a heat block. Ammonia is chilled, bilirubin is protected from light and a coagulation specimen travels at room temperature, so each of the others names a real requirement for the wrong reason.

How should a specimen that requires chilling be transported to the laboratory?

• a.Buried in a container of solid ice cubes, which hold their temperature longer than anything else
• b.In a household freezer compartment until a courier is available to take it across to the laboratory
• c.In a refrigerator at four degrees, after the tube has first been centrifuged on the collection floor
• d.In a slurry of crushed ice and water, so the whole tube cools evenly without freezing✓

A mixture of ice and water surrounds the tube completely and holds it near zero degrees without letting any part of the specimen freeze. Solid cubes touch the glass at points, so parts of the sample freeze and hemolyze while other parts stay warm. Freezing a whole blood specimen ruptures the cells, and a chilled specimen is not the same as a centrifuged and refrigerated one.

A patient has a central venous catheter and a stat potassium is ordered. Who may draw the specimen from that line?

• a.Only a nurse or other clinician specifically trained and authorised to access central lines✓
• b.The phlebotomist, provided the line is flushed with saline before and after the specimen is drawn
• c.The phlebotomist, as long as a discard volume of at least five millilitres is taken and thrown away
• d.Anyone in the department, because a central line needs no venipuncture skill

Accessing a central line carries risks of infection, air embolism and catheter damage, so it is restricted to staff trained and credentialled for it, and phlebotomists are usually not among them. Flushing and discarding are part of the technique for those who are authorised, not a substitute for the authorisation. A specimen drawn from a line without the discard is also diluted by whatever was infusing.

Before an arterial puncture at the radial site, what does the modified Allen test determine?

• a.Whether the radial artery is large enough to accept the gauge of needle that has been selected
• b.Whether the patient's blood pressure is high enough for the syringe to fill without aspiration
• c.Whether the ulnar artery can supply the hand if the radial artery becomes blocked✓
• d.Whether the patient has enough clotting factor to stop bleeding after the needle is withdrawn

Both hand arteries are compressed until the hand blanches, then the ulnar is released. Colour returning within a few seconds shows collateral circulation, so the hand would survive if the radial artery thrombosed after the puncture. It says nothing about vessel size, blood pressure or coagulation, and arterial puncture itself is performed only by personnel trained and authorised for it.

An arterial blood gas syringe has a small air bubble in it after collection. What must be done?

• a.Expel the bubble at once and cap the syringe, because air alters the measured oxygen✓
• b.Leave the bubble in place, since it will dissolve into the plasma long before analysis begins
• c.Draw the plunger back to enlarge the bubble so it can be seen and reported to the laboratory
• d.Shake the syringe vigorously so the bubble is dispersed evenly

Room air holds much more oxygen and much less carbon dioxide than blood, so a retained bubble raises the measured oxygen and lowers the carbon dioxide, which can make a hypoxic patient look adequately oxygenated. The bubble is expelled immediately, the syringe is capped, the specimen is mixed gently and it goes straight to the laboratory. Shaking hemolyzes the sample.

How long should pressure be held over an arterial puncture site compared with a venous one?

• a.The same length of time, because the puncture wound in the skin is identical in both cases
• b.Less time, because arterial pressure pushes the vessel walls together and seals the site faster
• c.Longer, three to five minutes, and longer still if the patient is anticoagulated✓
• d.No pressure is needed at all if a pressure dressing is applied directly over the site

An artery carries blood under far higher pressure than a vein, so it bleeds longer and can form a large deep hematoma if released early. Continuous firm pressure for three to five minutes is the usual minimum, extended for patients on anticoagulants or with a bleeding disorder, and the site is then rechecked. A dressing alone does not substitute for held pressure.

A serum cortisol is ordered for eight in the morning and the patient arrives at four in the afternoon instead. What should the phlebotomist do?

• a.Draw the specimen now and label it as the eight in the morning collection to keep the order intact
• b.Draw it now without comment, because cortisol is stable and the time of day is irrelevant
• c.Refuse the draw and send the patient home to return at eight in the morning another day
• d.Draw it, record the actual collection time, and notify the provider that the timing has changed✓

Cortisol follows a daily rhythm and is typically highest in the early morning and much lower late in the day, so an afternoon specimen cannot be compared with a morning reference interval. The phlebotomist records the true time and lets the provider decide whether to use it or rebook. Labelling a specimen with a time it was not drawn is falsification of a record.

A patient is scheduled for autologous blood donation. What does that mean?

• a.Blood is collected from a relative whose type has been matched
• b.Blood is collected and separated so that only the plasma is returned to the patient later on
• c.Blood is collected from several donors and pooled into one unit for a single planned operation
• d.The patient's own blood is collected in advance and stored for their own planned surgery✓

In an autologous donation the donor and the recipient are the same person, which removes the risk of a transfusion reaction and of transmitted infection. Blood taken from a named relative or friend is a directed donation, a different arrangement. Pooling units from several donors and returning a separated component are both different procedures with different indications.

Which requirement applies specifically to a blood bank specimen for a type and crossmatch?

• a.The tube is labelled at the bedside with the identifiers plus who drew it and when✓
• b.The tube must be the last one filled in the draw so that no additive can be carried into it
• c.The specimen must be collected by two phlebotomists together
• d.The tube must be transported to the laboratory in an ice slurry to preserve the red cell antigens

Almost every fatal transfusion reaction begins with a specimen labelled for the wrong patient, so blood bank rules add the collector's identity and the date and time to the usual identifiers, and the label goes on at the patient's side before the phlebotomist leaves. Two collectors are not required, the specimen travels at room temperature, and the blood bank tube is not drawn last.

Which specimen requires protection from light between collection and analysis?

• a.A potassium level, because light drives potassium out of the cells
• b.A blood culture set, because light kills the more fragile organisms before they can grow
• c.A serum bilirubin, because light breaks the pigment down and the result reads low✓
• d.A prothrombin time, because light activates the clotting factors and shortens the result

Bilirubin is photosensitive, and a specimen left in daylight or under a phototherapy lamp loses measurable pigment within an hour, which can hide a rising bilirubin in a jaundiced newborn. Carotene, vitamin A, vitamin B6 and folate are handled the same way. Light does not move potassium, kill culture organisms or activate coagulation factors.

A two-hour postprandial glucose is ordered. What instruction does the patient need?

• a.Fast for twelve hours and arrive with nothing to eat or drink since the previous evening
• b.Eat the meal the provider specified, then return exactly two hours after starting it✓
• c.Eat whatever the patient likes at any time, since the two-hour interval is the only variable
• d.Drink the standard glucose solution and wait for two hours

The two-hour postprandial specimen measures how the body handles a defined meal, so the patient eats the prescribed meal and the timing runs from the start of eating. Continuing to fast defeats the purpose, an unspecified meal makes the result impossible to compare, and drinking a measured glucose load is a tolerance test, which is a different order.

A blood culture set drawn from an arm with a running intravenous line grows a skin organism in one bottle only. What is the most likely explanation?

• a.Contamination introduced during collection rather than a true bloodstream infection✓
• b.A genuine bloodstream infection that the second set simply failed to detect on that occasion
• c.Contamination of the culture medium during manufacture, which requires a recall of the lot
• d.Cross contamination in the analyser, which incubates all of the bottles in one shared chamber

A skin organism in one bottle of one set, with the other bottles negative, is the classic pattern of contamination introduced at the puncture, usually from inadequate skin antisepsis or from touching the prepared site. Manufacturing contamination and analyser cross contamination are rare and would show a different pattern, and a true infection generally seeds more than one bottle.