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SU3.1-3 | Blood and Blood Components — Practice Quiz
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A 28-year-old woman is being transfused packed red cells for postpartum haemorrhage. Five minutes after the unit is started she develops fever, rigors, severe loin and back pain, hypotension and passes dark red urine. Which transfusion reaction is most likely?
Correct. Onset within minutes with fever, loin/back pain, hypotension and haemoglobinuria is the classic picture of an acute haemolytic reaction. It is almost always caused by ABO-incompatible blood, where preformed recipient IgM antibodies cause rapid intravascular complement-mediated haemolysis. The transfusion must be stopped immediately.
Acute haemolytic transfusion reaction is an emergency: stop the transfusion, keep IV access with saline, recheck patient and unit identity, and send samples to the blood bank. It results from ABO-incompatible blood and is preventable by rigorous bedside identity checks.
Reconsider the timing and features. Intravascular haemolysis (loin pain, hypotension, haemoglobinuria) appearing within minutes points to ABO incompatibility, not a febrile, circulatory or pulmonary cause.
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A patient with sepsis and a low platelet count of 12,000/µL is actively bleeding. Which blood component is most appropriate to correct the thrombocytopenia?
Correct. Component therapy means giving only the fraction the patient lacks. An actively bleeding patient with severe thrombocytopenia needs platelet concentrate, which is stored at 20–24 °C with gentle agitation for up to 5 days.
Platelets are stored at room temperature (20–24 °C) with agitation, unlike red cells (2–6 °C) and FFP/cryoprecipitate (frozen). Matching the component to the specific deficit is the core of safe, efficient transfusion practice.
The principle of component therapy is to replace only the missing fraction. Red cells correct anaemia, FFP replaces coagulation factors, and cryoprecipitate supplies fibrinogen — none directly raises the platelet count.
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Two hours into a unit of red cells, an elderly patient with chronic kidney disease develops increasing breathlessness, raised jugular venous pressure, hypertension and bilateral basal crepitations. Oxygen saturation is falling. Which complication has most likely occurred?
Correct. Hypertension, raised JVP and pulmonary oedema in a patient with limited cardiac/renal reserve indicate volume overload (TACO). It is managed by stopping/slowing the transfusion, sitting the patient up, giving oxygen and a diuretic.
TACO is fluid overload from transfusion, most likely in the elderly and those with cardiac or renal impairment. Prevention includes slow transfusion rates and prophylactic diuretics in at-risk patients; TRALI, by contrast, is hypotensive non-cardiogenic pulmonary oedema occurring within 6 hours.
Distinguish TACO from TRALI: TACO causes hypertension and signs of fluid overload (raised JVP), whereas TRALI typically causes hypotension and non-cardiogenic pulmonary oedema within 6 hours. The raised JVP and hypertension here point to circulatory overload.
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A trauma patient receives a massive transfusion of stored red cells. He becomes hypotensive with peri-oral tingling, prolonged QT interval and a positive Chvostek sign. Which metabolic complication of massive transfusion is responsible?
Correct. Citrate anticoagulant in stored blood chelates calcium; rapid massive transfusion overwhelms hepatic citrate metabolism, producing hypocalcaemia with tetany, prolonged QT and a positive Chvostek sign. Treat with IV calcium.
Massive transfusion (≈ one blood volume in 24 h) risks hypocalcaemia (citrate), hyperkalaemia (red-cell potassium leak), hypothermia (cold units) and dilutional coagulopathy. Use warmed blood, monitor ionised calcium and potassium, and replace calcium when indicated.
Peri-oral tingling, prolonged QT and a positive Chvostek sign are signs of hypocalcaemia, caused by citrate chelating calcium. Hyperkalaemia, hypothermia and coagulopathy are also features of massive transfusion but produce different findings.
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Before hanging a unit of red cells at the bedside, what is the single most important step to prevent an acute haemolytic transfusion reaction?
Correct. Most fatal haemolytic reactions arise from misidentification at the bedside. Ask the able patient to state their own full name and date of birth, then match these to the wristband AND the compatibility label on the unit before starting.
Positive identification means the patient does the talking: an able patient states their own full name and date of birth, which are then matched to the wristband and the unit's compatibility label. This bedside check is the final barrier preventing wrong-patient transfusion.
Warming, premedication and good IV access matter, but the commonest cause of fatal ABO-incompatible transfusion is bedside misidentification. The single most protective step is positive patient identification against the unit's compatibility label.
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A healthy 30-year-old man wishes to become a voluntary blood donor and asks what happens during and after donation. Which statement is the most appropriate counselling point?
Correct. Voluntary donation is safe; each unit is screened for transfusion-transmissible infections and typically fractionated into components so several patients benefit. Counselling should reassure the donor, explain the process, and confirm the inter-donation interval.
Donation counselling (SU3.3) should use plain language to explain consent, the safety and brief discomfort of the procedure, mandatory infection screening of every unit, component separation, and the recommended interval between whole-blood donations that allows haemoglobin to recover.
Effective donation counselling reassures the donor that the process is safe, that units are tested for infections and usually separated into components, and that donation intervals (around 12 weeks for whole blood in most guidelines) protect the donor's iron stores.
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