Transfusion medicine and haematology lab tests

39 NEET-PG practice questions on Transfusion medicine and haematology lab tests, part of Pathology. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

1. Question 1 · Medium

   At a CHC with no factor concentrates in stock, a known severe haemophilia A patient (factor VIII below 1%) arrives with a tense, painful knee haemarthrosis. Referral will take 6 hours. The blood centre has fresh frozen plasma, cryoprecipitate, platelets and packed red cells. Which component gives the most factor VIII in the smallest volume?

   1. AFresh frozen plasma
   2. BCryoprecipitate
   3. CCryo-poor plasma
   4. DPlatelet concentrate

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   Answer: B · Cryoprecipitate

   Cryoprecipitate concentrates factor VIII (at least 80 IU per bag), fibrinogen, vWF and factor XIII into a small volume, so it raises factor VIII far more per millilitre than fresh frozen plasma, which needs very large volumes. Factor VIII concentrate or emicizumab is preferred where available, because cryoprecipitate is not virally inactivated. Rest, ice and immobilisation of the joint help while factor is given.

   • A: FFP contains factor VIII but needs large volumes that risk overload.
   • C: Cryo-poor plasma has had most of its factor VIII and fibrinogen removed.
   • D: Platelets do not supply useful amounts of factor VIII.

   Remember this

   When factor VIII concentrate is not available, cryoprecipitate is the component of choice for haemophilia A.

2. Question 2 · Medium

   Platelets 38,000/µL, PT 26 s (control 13 s), aPTT 58 s (control 30 s), fibrinogen 70 mg/dL (normal 200-400) and D-dimer markedly raised, with schistocytes on the smear. These results are from a farmer in the ICU with meningococcal septicaemia and purpura. Which diagnosis do they indicate?

   1. AThrombotic thrombocytopenic purpura
   2. BVitamin K deficiency
   3. CDisseminated intravascular coagulation
   4. DImmune thrombocytopenia

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   Answer: C · Disseminated intravascular coagulation

   Low platelets, prolonged PT and aPTT, low fibrinogen, high D-dimer and schistocytes together show consumption of platelets and clotting factors with secondary fibrinolysis, which is disseminated intravascular coagulation. Sepsis, especially meningococcaemia, is a classic trigger through tissue factor expression on monocytes and endothelium. TTP also shows schistocytes and low platelets, but the PT, aPTT and fibrinogen are normal.

   • A: TTP gives schistocytes and thrombocytopenia with normal PT, aPTT and fibrinogen.
   • B: Vitamin K deficiency prolongs the PT, but platelets, fibrinogen and D-dimer are normal.
   • D: ITP causes isolated thrombocytopenia with normal clotting tests and no schistocytes.

   Remember this

   DIC shows low platelets, long PT and aPTT, low fibrinogen and high D-dimer; TTP has normal clotting times.

3. Question 3 · Easy

   Dark urine on waking, pancytopenia and a recent hepatic vein thrombosis are noted in a young man from Pune. LDH is high and the DAT is negative. Which investigation confirms the likely diagnosis?

   1. ABone marrow aspiration and trephine biopsy
   2. BSucrose lysis test
   3. CHam acid serum test
   4. DFlow cytometry for CD55 and CD59

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   Answer: D · Flow cytometry for CD55 and CD59

   Haemolysis with nocturnal haemoglobinuria, cytopenias and thrombosis at unusual sites is paroxysmal nocturnal haemoglobinuria. A PIGA mutation stops GPI anchor synthesis, so the complement regulators CD55 and CD59 are missing and red cells are lysed by complement. Flow cytometry of red cells, with FLAER-based testing of granulocytes, is the confirmatory test; the Ham and sucrose lysis tests are obsolete.

   • A: Marrow biopsy may show hypoplasia but cannot prove PNH.
   • B: Sucrose lysis is a crude screening test, now replaced by flow cytometry.
   • C: The Ham test is old, less sensitive and no longer recommended.

   Remember this

   PNH is confirmed by flow cytometry showing loss of GPI-anchored CD55 and CD59 (FLAER on white cells).

4. Question 4 · Hard

   On day 10 of high-dose IV benzylpenicillin for streptococcal endocarditis, a man in the cardiology ward has Hb falling from 11.6 to 8.1 g/dL, with spherocytes, reticulocytosis and raised LDH. His renal function and G6PD screen are normal. The DAT is strongly positive with anti-IgG and negative with anti-C3. His serum reacts only with penicillin-treated red cells, not with untreated reagent cells, and an eluate from his red cells behaves the same way. Haemolysis settles within 2 weeks of switching to vancomycin. What is the mechanism of his haemolysis?

   1. ADrug-antibody immune complexes fixing complement
   2. BOxidant injury in G6PD deficiency
   3. CDrug-induced autoantibody against Rh antigens
   4. DDrug adsorbed on red cells acting as a hapten

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   Answer: D · Drug adsorbed on red cells acting as a hapten

   In the hapten (drug-adsorption) mechanism, penicillin binds covalently to red-cell membrane proteins and IgG antibodies against the drug coat the cells, which are removed in the spleen; the DAT is IgG-positive, and serum and eluate react only with drug-treated cells. It needs high doses and recovers once the drug is stopped. Immune-complex types (ceftriaxone, quinine) fix complement and give C3-positive intravascular haemolysis, while methyldopa induces true autoantibodies that react with untreated cells.

   • A: Immune-complex haemolysis is complement-mediated with a C3-positive DAT, as with ceftriaxone.
   • B: G6PD haemolysis is DAT-negative, with bite cells and Heinz bodies.
   • C: Methyldopa-type autoantibodies react with untreated red cells, unlike here.

   Remember this

   Penicillin haemolysis is a hapten mechanism with an IgG-positive DAT and antibody that reacts only with drug-coated cells.

5. Question 5 · Hard

   At the anticoagulation clinic, a woman with a mechanical mitral valve on warfarin (target INR 2.5-3.5) has a PT of 36 s. The laboratory mean normal PT is 12 s, and the thromboplastin reagent has an ISI of 1.5. What is her INR?

   1. A5.2, above her target range
   2. B9.0, far above her target range
   3. C4.5, above her target range
   4. D3.0, within her target range

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   Answer: A · 5.2, above her target range

   INR = (patient PT / mean normal PT) raised to the power ISI = (36/12) to the power 1.5 = 3 to the power 1.5, about 5.2. The ISI corrects for the sensitivity of each thromboplastin against the WHO reference, so the ratio must be raised to it, not multiplied by it. An INR of 5.2 without bleeding is managed by withholding warfarin doses and rechecking, with low-dose oral vitamin K considered if bleeding risk is high.

   • B: 9.0 squares the ratio instead of raising it to the ISI.
   • C: 4.5 multiplies the ratio by the ISI instead of using it as an exponent.
   • D: 3.0 is the PT ratio alone, ignoring the ISI.

   Remember this

   INR = (patient PT / mean normal PT) to the power ISI; multiplying by the ISI is a common error.

6. Question 6 · Easy

   Coagulation profile of a boy with a swollen, painful knee after a minor fall; his maternal uncle had similar bleeds: platelet count 2.6 lakh/µL, bleeding time 4 min (normal 2-7), PT 13 s (control 12 s), aPTT 74 s (control 32 s). Which factor assay is most likely to be low?

   1. AFactor XIII
   2. BFactor VII
   3. CFibrinogen
   4. DFactor VIII

   Answer and explanation in LearnFree account

7. Question 7 · Medium

   A woman from Mumbai admitted for caesarean section is grouped as O Rh-positive by forward and reverse grouping. Every group O unit tested is incompatible at room temperature and 37 °C, and her own red cells do not react with anti-H lectin (Ulex europaeus). Which red cells can be safely transfused?

   1. AGroup O Rh-negative red cells
   2. BGroup AB Rh-positive red cells
   3. CWashed group O red cells
   4. DBombay (Oh) red cells

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8. Question 8 · Medium

   In the trauma theatre, a man with a crushed pelvis receives 14 units of red cells with plasma and platelets over 90 minutes. His liver function is poor from chronic alcohol use. He develops perioral tingling, muscle twitching and hypotension that does not respond to fluid, and the ECG shows a prolonged QT interval. Ionised calcium is 0.7 mmol/L (normal 1.1-1.3). What has caused this?

   1. ACitrate chelating ionised calcium
   2. BHypothermia from cold blood
   3. CPotassium released from stored red cells
   4. DDilution of clotting factors

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9. Question 9 · Medium

   Two days after starting warfarin, which test changes first, and why?

   1. APT, as prothrombin falls first
   2. BThrombin time, as fibrinogen falls
   3. CPT, as factor VII has the shortest half-life
   4. DaPTT, as factor IX is the first factor to fall

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10. Question 10 · Medium

    After a vaginal delivery complicated by placental abruption, an Rh D-negative mother has an Rh D-positive baby. A rosette screening test on her blood is positive, suggesting a large fetomaternal haemorrhage. Which test is used to quantify the bleed so the anti-D dose can be adjusted?

    1. AKleihauer-Betke acid elution test
    2. BRepeat rosette test after 24 hours
    3. CDirect antiglobulin test on cord blood
    4. DIndirect antiglobulin test on the mother

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11. Question 11 · Medium

    A haematology resident lists the effects of pre-storage leucoreduction of red cells. Which are correct? 1. Prevention of transfusion-associated graft-versus-host disease. 2. Fewer febrile non-haemolytic reactions. 3. Less HLA alloimmunisation and platelet refractoriness. 4. Lower risk of CMV transmission.

    1. A1, 2, 3 and 4
    2. B1, 2 and 4 only
    3. C2 and 3 only
    4. D2, 3 and 4 only

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12. Question 12 · Hard

    A woman with aplastic anaemia who has received more than 40 platelet units over 6 months has persistent gum bleeding. Before a single-donor apheresis platelet unit containing 3 x 10^11 platelets her count is 8,000/µL; one hour later it is 12,000/µL. Her body surface area is 1.8 m², and she has no fever, splenomegaly, DIC or active bleeding elsewhere, and takes no drugs such as amphotericin. Her blood group is O Rh-positive and the units were ABO-identical. Two earlier transfusions showed similar poor increments. What is the most appropriate next step?

    1. ATest for HLA antibodies and give HLA-matched platelets
    2. BArrange a splenectomy
    3. CStart IV immunoglobulin and continue the same units
    4. DDouble the dose of random-donor platelets

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13. Question 13 · Easy

    In the labour room, a woman with placental abruption is bleeding from venepuncture sites. Platelets are 62,000/µL, PT 24 s (control 13 s) and fibrinogen 80 mg/dL (normal 200-400). Besides fresh frozen plasma, which component best replaces her fibrinogen?

    1. ACryoprecipitate
    2. BProthrombin complex concentrate
    3. CPlatelet concentrate
    4. DCryo-poor plasma

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14. Question 14 · Medium

    As the medical officer in charge of a district hospital blood centre, you receive a request for 2 units cross-matched for an elective laparoscopic cholecystectomy in a fit woman with Hb 12.8 g/dL. Your maximum surgical blood order schedule shows that this operation rarely needs transfusion. What is the most appropriate response?

    1. AGroup and antibody screen only
    2. BCross-match 2 units as asked
    3. CNo blood bank sample needed
    4. DCross-match 1 unit as a compromise

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15. Question 15 · Medium

    Twenty minutes into a unit of red cells stored for 35 days, a patient on the oncology ward develops rigors, a temperature of 40 °C, BP 72/40 mmHg and vomiting. The bag contents look darker than usual, and Gram stain of the residual blood shows gram-negative coccobacilli. Which organism, able to grow at refrigerator temperature, is most often responsible in red cell units?

    1. AStreptococcus pyogenes
    2. BYersinia enterocolitica
    3. CStaphylococcus epidermidis
    4. DClostridium perfringens

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16. Question 16 · Easy

    Platelet concentrates in a blood centre are stored under which condition?

    1. A-30 °C or colder in a deep freezer
    2. B37 °C in a warm water bath
    3. C20-24 °C with gentle agitation
    4. D2-6 °C in a blood bank refrigerator

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17. Question 17 · Medium

    A newborn with Rh haemolytic disease (mother O Rh-negative, baby B Rh-positive) has cord Hb 9.8 g/dL and bilirubin rising by 1 mg/dL per hour despite intensive phototherapy. The paediatrician plans a double-volume exchange transfusion. Which red cells should the blood centre provide?

    1. AGroup B Rh-positive, cross-matched with baby's serum
    2. BGroup AB Rh-negative, cross-matched with baby's serum
    3. CGroup B Rh-negative, cross-matched with father's serum
    4. DGroup O Rh-negative, cross-matched with mother's serum

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18. Question 18 · Medium

    Which phase of a cross-match detects clinically significant IgG alloantibodies such as anti-Kell?

    1. ASaline phase at 22 °C
    2. BImmediate spin at room temperature
    3. CSaline phase at 4 °C
    4. DAntiglobulin phase at 37 °C

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19. Question 19 · Hard

    A retired railway clerk has generalised lymphadenopathy, splenomegaly and a lymphocyte count of 28,000/µL; Hb is 10.8 g/dL and platelets 1.1 lakh/µL, and he has lost 6 kg in 3 months. Colonoscopy for loose stools showed multiple small polyps. The smear shows small to medium lymphoid cells with irregular, notched nuclei and few smudge cells. Flow cytometry: CD19+, CD20 bright, CD5+, CD23 negative, CD200 negative, FMC7+, with bright surface lambda light chain restriction. Serum LDH is raised and CT shows bulky abdominal nodes. Which test should be done next to confirm the diagnosis?

    1. AFISH for t(14;18)
    2. BBRAF V600E mutation testing
    3. CCyclin D1 IHC or FISH for t(11;14)
    4. DFISH for deletion 17p and TP53 mutation

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20. Question 20 · Hard

    Ten days after cardiac surgery at a private hospital, a businessman develops fever, an erythematous rash spreading from the palms, profuse diarrhoea and deranged liver enzymes, followed by pancytopenia. During surgery he received two units of fresh whole blood, not irradiated, donated by his son. He is not otherwise immunosuppressed. Skin biopsy shows basal vacuolar change with apoptotic keratinocytes, and bone marrow is hypocellular. Blood cultures are sterile, and despite supportive care his counts keep falling. Lymphocytes in his blood carry the son's HLA type. Which feature of the donation best explains why this happened?

    1. ADonor plasma containing anti-HLA antibodies
    2. BDonor red cells carrying a minor blood group antigen
    3. CDonor homozygous for a shared HLA haplotype
    4. DBacterial contamination of fresh whole blood

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21. Question 21 · Medium

    Platelet studies in a girl with lifelong nosebleeds and heavy menses: platelet count 70,000/µL with giant platelets, prolonged bleeding time, normal aggregation with ADP, collagen and epinephrine, but no agglutination with ristocetin, not corrected by adding normal plasma. Her parents are first cousins. Flow cytometry of her platelets will show reduced expression of:

    1. ACD62P (P-selectin)
    2. BCD41 (GpIIb)
    3. CCD42b (GpIb)
    4. DCD61 (GpIIIa)

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22. Question 22 · Medium

    Enoxaparin for a pregnant woman with a mechanical heart valve and reduced renal function is best monitored by which test?

    1. APT and INR
    2. BAnti-factor Xa level
    3. CaPTT
    4. DThrombin time

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23. Question 23 · Easy

    In an adult of average size who is not bleeding, one unit of packed red cells is expected to raise the haemoglobin by about:

    1. A1 g/dL
    2. B4 g/dL
    3. C2.5 g/dL
    4. D0.25 g/dL

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24. Question 24 · Medium

    A pathology resident reviews antiglobulin (Coombs) tests. Which statements are correct? 1. The direct test is positive in warm autoimmune haemolytic anaemia. 2. The indirect test is used for antenatal antibody screening. 3. The direct test is positive in hereditary spherocytosis. 4. The antiglobulin phase of a cross-match is an indirect test.

    1. A1, 2, 3 and 4
    2. B1, 2 and 4 only
    3. C2, 3 and 4 only
    4. D1 and 2 only

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25. Question 25 · Medium

    Eight days after a red cell transfusion during a hip replacement, a woman with three previous pregnancies develops widespread purpura, nosebleeds and blood in the urine. Her platelet count, 2.1 lakh/µL before surgery, is now 6,000/µL. She has received no heparin since the operation, PT, aPTT and fibrinogen are normal, and the smear shows no schistocytes. Platelet antibody testing finds anti-HPA-1a, and her own platelets type as HPA-1a negative. A platelet transfusion given in the casualty produced no rise in count. What is the treatment of choice?

    1. AHigh-dose IV immunoglobulin
    2. BPlasma exchange with fresh frozen plasma
    3. CEmergency splenectomy
    4. DRandom-donor platelet transfusion

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