Thrombosis, Anticoagulants, and Transfusion Practice Questions

25 multiple-choice questions on Thrombosis, anticoagulants, and transfusion for paramedic and EMT students, from Chapter 25 (Hematologic Emergencies). Read each question, pick your answer, then tap Show answer to check it and read the explanation.

25 practice questions

1. For a stable, non-bleeding hospitalized adult, red cell transfusion is generally recommended once the hemoglobin falls below about:

   1. A. 4 g/dL
   2. B. 7 g/dL
   3. C. 10 g/dL
   4. D. 12 g/dL
   Show answer

   Answer: B. 7 g/dL

   A restrictive threshold of about 7 g/dL is as safe as a liberal one for most patients. Higher thresholds (about 8 g/dL) apply to heart surgery and some cardiac patients. Bleeding patients are treated by blood loss and perfusion, not by a number.

2. In a non-bleeding adult, one unit of packed red cells usually raises the hemoglobin by about:

   1. A. 0.1 g/dL
   2. B. 1 g/dL
   3. C. 3 g/dL
   4. D. 5 g/dL
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   Answer: B. 1 g/dL

   A unit raises hemoglobin by about 1 g/dL (hematocrit by about 3%) in an average adult. Ongoing bleeding blunts the rise.

3. During a platelet transfusion, a patient develops rigors, a temperature of 40 °C (104 °F), and a BP of 78/40 mm Hg. The most likely cause is:

   1. A. A mild allergic reaction
   2. B. Circulatory overload
   3. C. A febrile nonhemolytic transfusion reaction
   4. D. Bacterial contamination of the unit
   Show answer

   Answer: D. Bacterial contamination of the unit

   Platelets carry the highest risk of bacterial growth of any blood product. High fever, rigors, and shock during the transfusion suggest septic transfusion. Stop it, treat shock, and save the bag.

4. A patient with a PICC line in her right arm has new swelling and aching of that arm with visible veins over the shoulder. There is no redness or fever. You should suspect:

   1. A. An allergy to the dressing
   2. B. Muscle strain from arm use
   3. C. A clot in the arm veins
   4. D. Phlebitis at the insertion site
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   Answer: C. A clot in the arm veins

   Central lines, including PICCs, are the leading cause of upper-extremity DVT. Arm swelling and prominent shoulder veins suggest a clot that can still embolize.

5. Which advice best lowers DVT risk during a long flight?

   1. A. Walk and flex the calves often
   2. B. Sleep deeply through the flight
   3. C. Limit fluids to avoid the bathroom
   4. D. Sit with the legs tightly crossed
   Show answer

   Answer: A. Walk and flex the calves often

   Moving and contracting the calf muscles keeps venous blood flowing. Long immobility, dehydration, and pressure on the veins all add to stasis.

6. A patient who received two units of blood a week ago now has jaundice, dark urine, and a falling hemoglobin. The most likely cause is:

   1. A. Transfusion-related acute lung injury
   2. B. Circulatory overload from the transfusion
   3. C. A febrile nonhemolytic reaction
   4. D. A delayed hemolytic transfusion reaction
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   Answer: D. A delayed hemolytic transfusion reaction

   Antibodies to minor red cell antigens can rise days to weeks after a transfusion and destroy the donor cells more slowly than an ABO reaction. TRALI and overload occur within hours.

7. Antiphospholipid syndrome increases the risk of:

   1. A. Bleeding and bruising
   2. B. Clots and miscarriage
   3. C. Anemia and jaundice
   4. D. Infection only
   Show answer

   Answer: B. Clots and miscarriage

   It is an autoimmune condition, often linked to lupus, that causes arterial and venous clots.

8. Factor V Leiden is:

   1. A. An inherited clotting tendency
   2. B. An inherited bleeding disorder
   3. C. A slow-growing form of leukemia
   4. D. A delayed transfusion reaction
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   Answer: A. An inherited clotting tendency

   It is the most common inherited thrombophilia in people of European descent.

9. Rapid transfusion of many older units of stored red cells can cause:

   1. A. Hypercalcemia
   2. B. Hypernatremia
   3. C. Hyperkalemia
   4. D. Hypermagnesemia
   Show answer

   Answer: C. Hyperkalemia

   Potassium leaks out of red cells during storage, so rapid infusion of older units, especially in children or through central lines, can raise the potassium and trigger arrhythmias.

10. Packed red cells must be kept at about what temperature until use?

    1. A. 1 to 6 °C (34 to 43 °F)
    2. B. -18 °C (0 °F) or colder
    3. C. 20 to 24 °C (68 to 75 °F)
    4. D. 37 °C (99 °F)
    Show answer

    Answer: A. 1 to 6 °C (34 to 43 °F)

    Red cells are refrigerated in validated coolers and discarded if they warm beyond the allowed range. Plasma is stored frozen.

11. The main advantage of DOACs over warfarin is:

    1. A. Easy reversal with vitamin K
    2. B. Protection from GI bleeding
    3. C. Safety in severe kidney failure
    4. D. No routine INR monitoring
    Show answer

    Answer: D. No routine INR monitoring

    DOACs have fewer drug and diet interactions but still cause bleeding.

12. A transfusion reaction is most likely to begin:

    1. A. After the unit is finished
    2. B. In the first 15 minutes
    3. C. The next day
    4. D. After several weeks
    Show answer

    Answer: B. In the first 15 minutes

    Severe reactions usually start early, so watch closely at the beginning of a transfusion.

13. The first step if a transfusion reaction is suspected is to:

    1. A. Slow the drip rate
    2. B. Give diphenhydramine IV
    3. C. Stop the transfusion
    4. D. Remove the IV catheter
    Show answer

    Answer: C. Stop the transfusion

    Stop the blood, keep the IV open with saline, treat symptoms, and save the bag and tubing. Slowing the rate still gives more of the unit, and an antihistamine treats symptoms but does not stop the exposure. Keep the IV, because it may be needed for fluids and drugs.

14. An acute hemolytic transfusion reaction is most often due to:

    1. A. Iron overload
    2. B. Platelet clumping in the bag
    3. C. Cold blood
    4. D. ABO incompatibility
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    Answer: D. ABO incompatibility

    The recipient's antibodies attack donor red cells of the wrong ABO type and destroy them inside the vessels.

15. Signs of an acute hemolytic transfusion reaction include:

    1. A. Fever, back pain, dark urine
    2. B. Itchy hives and flushing
    3. C. Bradycardia and severe hypertension
    4. D. Hyperglycemia
    Show answer

    Answer: A. Fever, back pain, dark urine

    Destroyed red cells cause shock, DIC, and kidney failure.

16. A patient receiving blood develops itching and hives but has normal vital signs. This is most likely:

    1. A. An acute hemolytic reaction
    2. B. A mild allergic reaction
    3. C. TRALI
    4. D. Sepsis
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    Answer: B. A mild allergic reaction

    Stop the transfusion and give an antihistamine per protocol. Watch for anaphylaxis.

17. A febrile nonhemolytic reaction is caused by:

    1. A. ABO incompatibility
    2. B. Bacterial contamination
    3. C. White cell antibodies
    4. D. Iron overload
    Show answer

    Answer: C. White cell antibodies

    It causes fever and chills without hemolysis. It is the most common transfusion reaction.

18. Transfusion-associated circulatory overload (TACO) presents with:

    1. A. Dyspnea, crackles, and hypertension
    2. B. Itchy hives and generalized flushing
    3. C. Hypothermia, bradycardia, and chills
    4. D. Joint bleeding and new bruising
    Show answer

    Answer: A. Dyspnea, crackles, and hypertension

    Giving blood too fast, especially in elderly or cardiac patients, causes pulmonary edema.

19. TRALI (transfusion-related acute lung injury) presents with:

    1. A. Hypertension and bradycardia
    2. B. Hives with normal oxygen levels
    3. C. Hypoxia, noncardiogenic edema
    4. D. Fever and back pain
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    Answer: C. Hypoxia, noncardiogenic edema

    TRALI occurs within 6 hours. Unlike TACO, blood pressure is often low.

20. Anaphylaxis during a transfusion is treated with:

    1. A. Stopping blood, giving diphenhydramine
    2. B. Slowing the rate, giving epinephrine
    3. C. Stopping blood, giving a diuretic
    4. D. Stopping blood, giving epinephrine
    Show answer

    Answer: D. Stopping blood, giving epinephrine

    Stop the transfusion and treat like any anaphylaxis with IM epinephrine; patients with IgA deficiency are at risk. An antihistamine alone does not reverse airway swelling or shock. Slowing the rate still delivers more of the trigger. A diuretic treats circulatory overload, not anaphylaxis.

21. Which step best prevents an ABO-incompatible transfusion?

    1. A. Warming the blood before infusing it
    2. B. Two-person check of patient ID and the unit
    3. C. Running the first 50 mL in rapidly
    4. D. Premedicating with acetaminophen and diphenhydramine
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    Answer: B. Two-person check of patient ID and the unit

    Most ABO reactions come from clerical errors such as the wrong patient or the wrong unit. Two people checking identity against the label at the bedside prevents them. Premedication does not prevent hemolysis.

22. Why should blood be warmed during rapid transfusion?

    1. A. Warm blood clots faster in the bag
    2. B. Cold blood causes immediate hemolysis
    3. C. Warming kills bacteria in the unit
    4. D. Cold blood causes hypothermia
    Show answer

    Answer: D. Cold blood causes hypothermia

    Stored blood is refrigerated. Rapid infusion lowers body temperature and worsens coagulopathy.

23. Which IV fluid may be used with blood products?

    1. A. Lactated Ringer's
    2. B. Normal saline
    3. C. D5W
    4. D. D50
    Show answer

    Answer: B. Normal saline

    Dextrose solutions cause hemolysis, and the calcium in LR can cause clotting in the line.

24. Whole blood or a balanced 1:1:1 ratio is used in hemorrhagic shock to:

    1. A. Raise the blood pressure to a normal level
    2. B. Restore the hematocrit above 45%
    3. C. Replace cells, factors, and platelets
    4. D. Lower the risk of hyperkalemia
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    Answer: C. Replace cells, factors, and platelets

    Balanced resuscitation treats trauma coagulopathy better than red cells alone. The goal is not a normal blood pressure, since permissive hypotension is used until bleeding is controlled, or a high hematocrit. Large transfusions can raise potassium rather than prevent it.

25. Platelet units carry a higher risk of bacterial contamination than red cells mainly because they are:

    1. A. Stored at room temperature
    2. B. Stored for up to 42 days
    3. C. Frozen and thawed before use
    4. D. Collected without sterile tubing
    Show answer

    Answer: A. Stored at room temperature

    Platelets lose function when refrigerated, so they are kept at about 20 to 24 °C, where bacteria can grow. Red cells are refrigerated and plasma is frozen. Red cells, not platelets, can be stored for up to 42 days; platelets last only about 5 to 7 days. Platelets are not frozen, and all units are collected in closed sterile systems.