23 Venipuncture Procedure & Complications Practice Questions & Answers

1. 1. An inpatient's wristband shows a date of birth that does not match the date of birth on the requisition, although the name matches in both places. What should the phlebotomist do first?

   • A.Draw the tubes now and let the processing staff correct the record after the specimens arrive
   • B.Hold the draw and ask the patient's nurse to resolve the mismatch and re-band the patient✓ Answer
   • C.Ask the patient to confirm the requisition date of birth with a simple yes-or-no question
   • D.Draw the tubes now and write the wristband date of birth on every label at the bedside

   Two independent identifiers must agree on both the requisition and the armband before any collection, so a date-of-birth mismatch means the identity is unverified and the draw stops until the nurse corrects the band. A yes-or-no confirmation is a leading question and is never an acceptable substitute for active identification.

   Source: NHA CPT Test Plan, Patient Preparation; CLSI GP41 patient identificationReport a problem with this question

2. 2. A competent adult patient says he does not want this blood test and pulls his sleeve back down. What is the appropriate response?

   • A.Record the tests as collected and leave the empty tubes for the nurse to handle
   • B.Explain that the provider ordered it and proceed once the patient stops objecting
   • C.Ask a family member at the bedside to consent to the venipuncture on his behalf
   • D.Stop, document the refusal in the record, and notify the patient's nurse or provider✓ Answer

   Consent may be withdrawn at any moment, and a competent adult who refuses cannot be drawn; proceeding anyway would be an unconsented procedure. The phlebotomist documents the refusal and passes it to the nurse or ordering provider, who decides what happens next, and a relative cannot consent for a competent adult.

   Source: NHA CPT Test Plan, consent and refusal; Patient Bill of RightsReport a problem with this question

3. 3. A patient has a functioning arteriovenous fistula in the right forearm and an intravenous infusion running in the left forearm. Where should the specimen be collected?

   • A.From the right hand on the fistula side, using a smaller gauge to reduce the pressure
   • B.From the left arm above the infusion, leaving the drip running throughout the collection
   • C.From a vein distal to the fistula in the right forearm, using a winged collection set
   • D.From the left arm below the infusion, after the nurse has stopped the drip for two minutes✓ Answer

   A limb carrying an arteriovenous fistula or graft is never punctured, because of the risk of infection and of clotting the access, and that exclusion covers the hand on that side as well. The infusion arm may be used only distal to the IV after the nurse turns the infusion off for about two minutes, and the specimen is documented as drawn below an IV; drawing above a running line dilutes it with fluid.

   Source: CLSI GP41 site selection; NHA CPT Test PlanReport a problem with this question

4. 4. While searching for a vein, a phlebotomist leaves the tourniquet in place far longer than a minute. Which effect on the results is most likely?

   • A.Hemodilution, which falsely lowers potassium, total protein and calcium results
   • B.Glycolysis, which falsely lowers the glucose but leaves the total protein unchanged
   • C.Hemoconcentration, which falsely raises potassium, total protein and calcium✓ Answer
   • D.Fibrin formation, which falsely lowers the platelet count in that same specimen

   Prolonged tourniquet pressure drives water out of the vessel at that site, concentrating cells and everything bound to protein, so potassium, calcium, total protein, cholesterol and packed cell volume all read falsely high. Stasis also promotes hemolysis, which pushes potassium higher still, which is why the tourniquet is released as soon as blood flow is established.

   Source: CLSI GP41 tourniquet application; NHA CPT Test PlanReport a problem with this question

5. 5. Immediately before entering the vein, how should the phlebotomist hold the skin and the needle?

   • A.Pinch the vein between the thumb and finger and enter bevel up at roughly 45 degrees
   • B.Anchor the skin above the site with a finger and enter bevel down at 15 to 30 degrees
   • C.Stretch the skin from both sides of the vein and enter bevel down at roughly 45 degrees
   • D.Anchor the skin below the site with the thumb and enter bevel up at 15 to 30 degrees✓ Answer

   Pulling the skin taut an inch or two below the site fixes the vein so it cannot roll and keeps the anchoring thumb behind the needle rather than in its path. A bevel-up entry at a shallow 15 to 30 degree angle lets the opening seat inside the lumen instead of shearing through the far wall.

   Source: CLSI GP41 venipuncture technique; NHA CPT Test PlanReport a problem with this question

6. 6. The last tube has filled. What is the correct order for the remaining steps?

   • A.Release the tourniquet, withdraw the needle, activate the safety device, then apply pressure✓ Answer
   • B.Activate the safety device, release the tourniquet, withdraw the needle, then apply pressure
   • C.Release the tourniquet, press on the site over the needle, withdraw it, then activate safety
   • D.Withdraw the needle, release the tourniquet, apply pressure, then activate the safety device

   The tourniquet comes off before the needle so that venous pressure is no longer raised when the vein is opened to the tissue, which is a leading cause of hematoma. The safety feature is engaged the instant the needle leaves the arm, and only then is pressure applied to the site with the arm held straight until bleeding stops.

   Source: CLSI GP41 completion of the venipuncture; NHA CPT Test PlanReport a problem with this question

7. 7. Blood runs into the first tube and then stops after a few milliliters. The needle has not moved and the vein still feels full. What should be tried first?

   • A.Seat a fresh tube on the holder, because the first tube may have lost vacuum✓ Answer
   • B.Remove the tourniquet completely and ask the patient to pump the fist hard
   • C.Withdraw the needle part way and redirect it sideways in search of the vein
   • D.Advance the needle through the far vein wall to reach a faster blood channel

   Flow that starts and then stops usually means that tube's vacuum is exhausted or was incomplete, so exchanging the tube is the first and least invasive check. Redirecting the needle sideways is lateral probing, which risks nerve injury, and vigorous fist pumping falsely raises the potassium result.

   Source: CLSI GP41 troubleshooting an unsuccessful draw; NHA CPT Test PlanReport a problem with this question

8. 8. Two venipuncture attempts on the same patient have both failed. What should the phlebotomist do next?

   • A.Try a third site on the opposite arm before involving any other staff member
   • B.Cancel the orders in the computer and ask the provider to reorder the tests
   • C.Collect the sample by capillary puncture and label it as a venous specimen
   • D.Stop and ask another phlebotomist or the patient's nurse to take over the draw✓ Answer

   Repeated punctures increase the risk of hematoma, nerve injury and patient distress, so after two unsuccessful attempts the collection is handed to a second collector rather than continued. Relabeling a capillary sample as venous falsifies the record, and canceling a provider's orders is outside the phlebotomist's scope.

   Source: CLSI GP41 limits on repeat attempts; NHA CPT Test PlanReport a problem with this question

9. 9. As the needle is advanced, the patient reports a sharp electric pain shooting into the thumb, with tingling. What should the phlebotomist do first?

   • A.Discontinue the draw at once, withdraw the needle, and report the event✓ Answer
   • B.Reposition the needle slightly and go on if the pain begins to settle
   • C.Loosen the tourniquet and fill the tube quickly to shorten the discomfort
   • D.Finish the collection and then apply a cold compress to the arm afterward

   Shooting or electric pain with tingling or numbness suggests the needle has struck or is irritating a nerve, and continuing or repositioning can turn a transient injury into a lasting one. The needle is withdrawn immediately and the incident is reported and documented, since nerve injury is a reportable complication.

   Source: CLSI GP41 nerve injury during venipuncture; NHA CPT Test PlanReport a problem with this question

10. 10. Bright red blood pulses into the tube and fills it unusually fast. What is the correct action?

    • A.Keep the needle in place and slow the flow by loosening the tourniquet a little
    • B.Finish the tubes, bandage the arm and note the rapid fill on the requisition
    • C.Remove the needle and hold firm pressure for at least five minutes, then report✓ Answer
    • D.Remove the needle and let the patient hold a light dressing over the site alone

    Bright red pulsating blood that fills a tube very quickly indicates an artery has been entered, and arterial pressure will produce a large hematoma unless the site is compressed hard for at least five minutes. The needle comes out immediately, a supervisor is notified, and the specimen is identified as arterial because some results differ from venous blood.

    Source: CLSI GP41 accidental arterial puncture; NHA CPT Test PlanReport a problem with this question

11. 11. A swelling rises quickly under the skin at the puncture site while the second tube is filling. What should the phlebotomist do first?

    • A.Withdraw the needle and rub the site briskly to spread the pooled blood out
    • B.Release the tourniquet, withdraw the needle and press firmly over the site✓ Answer
    • C.Leave the needle in and press above the site until the swelling stops growing
    • D.Finish the tube quickly, then apply a warm compress to disperse the swelling

    A swelling that appears during the draw is blood leaking into the tissue, usually because the bevel is only partly in the lumen or has passed through the far wall, and continuing enlarges the hematoma. The tourniquet is released, the needle removed and firm direct pressure applied; a cold pack afterward limits swelling, while heat or rubbing increases bleeding.

    Source: CLSI GP41 hematoma formation; NHA CPT Test PlanReport a problem with this question

12. 12. Midway through the collection the patient turns pale and sweaty and says the room is spinning. What should the phlebotomist do first?

    • A.Hold an ammonia inhalant under the nose and finish the remaining tube fast
    • B.Stop the draw, remove the needle and lower the head, staying with the patient✓ Answer
    • C.Leave to find help and let the patient rest quietly in the chair meanwhile
    • D.Ask the patient to sit up straighter and keep talking while the draw goes on

    Pallor, sweating and dizziness are the warning signs of syncope, and a patient who faints with a needle in the arm can be injured, so the needle comes out first. The head is lowered between the knees or the patient is laid flat and never left alone; ammonia inhalants are no longer used because they can provoke bronchospasm in asthmatic patients.

    Source: NHA CPT Test Plan, first aid; CLSI GP41 adverse patient reactionsReport a problem with this question

13. 13. Small flat red pinpoint spots appear on the forearm below the tourniquet. What does this most likely indicate?

    • A.A capillary or platelet defect, so prolonged bleeding at the site is likely✓ Answer
    • B.A hematoma is already forming, so the specimen must be discarded and redrawn
    • C.The tourniquet is too loose, so the vein will collapse once the flow starts
    • D.An allergy to the tourniquet material, so the bleeding time will be normal

    Petechiae are tiny capillary hemorrhages and point to a platelet or capillary fragility problem in the patient rather than to a technique error. They are not by themselves a reason to cancel the collection, but they warn the phlebotomist that the site is likely to bleed longer than usual and that pressure must be held accordingly.

    Source: NHA CPT Test Plan, complications; CLSI GP41 patient assessmentReport a problem with this question

14. 14. A patient taking warfarin is still bleeding at the site after the usual period of pressure. What should the phlebotomist do first?

    • A.Clean the site with alcohol again and cover it with a fresh adhesive bandage
    • B.Keep applying direct pressure with the arm raised and notify the nurse if it goes on✓ Answer
    • C.Wrap the arm tightly in a pressure bandage and send the patient on their way
    • D.Place a cotton ball and have the patient bend the elbow firmly for five minutes

    Anticoagulants prolong bleeding, so the first response is continued direct pressure over the site with the arm elevated, and the nurse or provider is informed if bleeding does not stop within about five minutes. Bending the elbow instead of pressing on the site is a classic cause of hematoma, and a tight wrap conceals continued bleeding rather than controlling it.

    Source: NHA CPT Test Plan, post-puncture care; CLSI GP41Report a problem with this question

15. 15. A patient says that adhesive bandages leave an itchy raised rash on the skin. What is the best action?

    • A.Put an antihistamine cream on the site before covering it with the usual bandage
    • B.Place the adhesive bandage over folded gauze so the tape never touches the skin
    • C.Apply the usual adhesive bandage and tell the patient to take it off in an hour
    • D.Hold gauze in place with a self-adhering wrap or paper tape instead of a bandage✓ Answer

    A reported adhesive sensitivity is respected by choosing a different dressing, such as gauze secured with a self-adhering wrap or paper tape, and the reaction is noted in the patient's record. Applying any medication is outside the phlebotomist's scope of practice, and the edges of the tape still contact skin even when the gauze pad underneath is enlarged.

    Source: NHA CPT Test Plan, post-puncture care and allergy assessmentReport a problem with this question

16. 16. When and where should the collected tubes be labeled?

    • A.Before the venipuncture begins, so each tube is ready as it fills in sequence
    • B.At the nurses' station immediately after leaving the room, from the requisition
    • C.In the laboratory at accessioning, by matching the tubes against the requisition
    • D.At the bedside in the patient's presence, right after the draw and before leaving✓ Answer

    Labeling in front of the patient before leaving the room is what links the tube to the identity that was just verified; any step taken later allows tubes from different patients to be confused. Pre-labeling is equally unsafe, because a label applied before the draw may end up on blood from someone else.

    Source: CLSI GP41 specimen labeling at the point of collection; NHA CPT Test PlanReport a problem with this question

17. 17. Processing staff find an unlabeled lavender tube delivered in a bag with a single requisition. What should happen to it?

    • A.It is rejected and recollected, since identity cannot be reconstructed after the fact✓ Answer
    • B.It is labeled by the collector now, since the collector still recalls that patient
    • C.It is labeled from the requisition, since only one patient's tube was in that bag
    • D.It is tested and reported with a comment noting the tube arrived without a label

    An unlabeled tube has no verifiable link to a patient, and a label added afterward is a guess no matter how confident the collector feels, so the specimen is rejected and a new one collected. Reporting a result from an unidentified specimen risks giving one patient another patient's result, which is why unlabeled specimens are a standing rejection criterion.

    Source: NHA CPT Test Plan, specimen rejection criteria; CLSI GP41 labelingReport a problem with this question

18. 18. The vein collapses and a light blue coagulation tube is left only half full, so the blood-to-citrate ratio is wrong. What follows?

    • A.The results are unaffected, because the analyzer corrects for the volume collected
    • B.The prothrombin time and aPTT come back falsely prolonged, so it is recollected✓ Answer
    • C.The plasma clots inside the tube, so the analyzer reports the sample as unreadable
    • D.The prothrombin time and aPTT come back falsely shortened, so the tube may be run

    The citrate tube is designed for a nine-to-one ratio of blood to anticoagulant, so an underfilled tube carries excess citrate, which binds more calcium and makes clot formation look slower than it truly is. The prothrombin time, INR and aPTT are therefore falsely prolonged, and a short-drawn coagulation tube is a standing rejection criterion requiring recollection.

    Source: CLSI GP41 tube fill and 9:1 citrate ratio; NHA CPT Test PlanReport a problem with this question

19. 19. After centrifugation the serum of a chemistry specimen is distinctly pink. Which result is most affected?

    • A.Sodium, falsely raised because plasma water has shifted into the red cells
    • B.Potassium, falsely raised because it leaks out of the ruptured red cells✓ Answer
    • C.Calcium, falsely raised because the damaged membranes bind less of it
    • D.Glucose, falsely raised because the red cells release their stored sugar

    Pink serum means red cells have ruptured, and potassium is roughly twenty-five times more concentrated inside the red cell than in plasma, so even mild hemolysis raises the measured value sharply. Magnesium, phosphorus, ammonia, LDH and AST rise for the same reason, and a visibly hemolyzed specimen is rejected for these analytes and recollected.

    Source: NHA CPT Test Plan, specimen integrity; CLSI GP41 hemolysisReport a problem with this question

20. 20. A tube for glucose and potassium sat on the bench for four hours before it was centrifuged. What is expected?

    • A.Both unchanged, because the separator gel had already walled off the red cells
    • B.Glucose falsely high and potassium falsely low, as the cells release stored sugar
    • C.Glucose falsely low and potassium falsely high, as cells consume sugar and leak✓ Answer
    • D.Both falsely low, because the cells keep taking up glucose and potassium alike

    While cells remain in contact with serum they keep metabolizing glucose, which falls by roughly five to seven percent per hour, and potassium leaks out of the cells down its concentration gradient. That is why serum or plasma must be separated from the cells within two hours of collection, and why unspun whole blood is not refrigerated.

    Source: NHA CPT Test Plan, processing; CLSI GP41 two-hour separation requirementReport a problem with this question

21. 21. Of the specimens described below, which one is being handled correctly on the way to the laboratory?

    • A.A bilirubin specimen wrapped in foil so that light cannot reach the sample✓ Answer
    • B.A lactic acid specimen packed against solid ice cubes rather than a slurry
    • C.A cold agglutinin specimen refrigerated for the trip to the testing bench
    • D.An ammonia specimen carried at room temperature to stop the cells lysing

    Bilirubin is degraded by light, so its tube travels wrapped in foil or in an amber container. Ammonia and lactic acid must instead be chilled in an ice-water slurry, which cools evenly without freezing and hemolyzing the sample, while cold agglutinins must be kept warm at body temperature until the serum has been separated.

    Source: NHA CPT Test Plan, special handling; CLSI GP41 specimen transport requirementsReport a problem with this question

22. 22. A blood culture set is being drawn with a winged collection set into paired bottles. Which practice is correct?

    • A.Palpate the vein once more after cleaning, then fill whichever bottle is nearer
    • B.Scrub with friction, dry the site by fanning it, and fill the anaerobic bottle first
    • C.Scrub with friction, let the site dry fully, and inoculate the aerobic bottle first✓ Answer
    • D.Underfill both bottles a little so that the broth is not diluted by the blood

    The antiseptic kills skin flora only while it is drying, so the prepared site is left to air dry untouched; fanning it or re-palpating it recontaminates the skin and produces false-positive cultures. With winged tubing the air in the line is pushed into the first bottle filled, so the aerobic bottle goes first, and each bottle must receive its full recommended volume because sensitivity depends on volume.

    Source: CLSI GP41 blood culture collection; NHA CPT Test PlanReport a problem with this question

23. 23. A blood alcohol specimen is being collected for a legal case. Which practice is correct?

    • A.Clean with an alcohol pad, then uncap the tube to check that it filled fully
    • B.Clean with a non-alcohol antiseptic and send the tube without any signatures
    • C.Clean with an isopropyl alcohol pad and note the collection time on the form
    • D.Clean with a non-alcohol antiseptic and complete the chain of custody record✓ Answer

    An alcohol-based skin prep can contaminate the specimen and hands the defense an obvious challenge, so an aqueous antiseptic such as benzalkonium chloride or soap and water is used instead. Legal specimens also require an unbroken chain of custody with signatures, dates and times, and the tube is filled and left capped because alcohol evaporates from an opened tube.

    Source: NHA CPT Test Plan, legal specimens and chain of custody; CLSI GP41Report a problem with this question

Concept-focused practice questions based on CLSI GP41 (venous blood collection), the CLSI order of draw, and the OSHA Bloodborne Pathogens Standard (29 CFR 1910.1030). Not affiliated with the NHA, ASCP, or CLSI, and not medical advice. Facility protocols and current CLSI standards take precedence — always follow your employer's procedures. About the CPT exam →