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PA13.{1,3} | Hematopoiesis & Blood Specimen Basics — Graded Quiz
Graded
12 questions · Untimed · 2 attempts
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A 42-year-old man develops progressive pancytopenia following chemotherapy for lymphoma. A bone marrow biopsy shows near-total aplasia with scattered fat cells. After allogeneic stem cell transplantation, engraftment is confirmed by rising neutrophil counts at day +14. Which property of the donor haematopoietic stem cells (HSCs) is MOST essential for sustained, life-long haemopoiesis in the recipient?
A
Ability to differentiate into all lymphoid lineages only
B
Self-renewal combined with multipotency
✓
C
High expression of EPO receptors ensuring rapid erythroid expansion
D
Constitutive production of granulocyte colony-stimulating factor
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A 7-year-old child with beta-thalassaemia major has progressive hepatosplenomegaly despite monthly blood transfusions. A radiograph of the skull shows a 'hair-on-end' pattern. His haemoglobin is 5.8 g/dL. Which pathophysiological sequence BEST explains the radiological finding?
A
Iron overload causing direct cortical bone erosion from repeated transfusions
B
Expansion of the diploe due to erythroid hyperplasia driven by chronic hypoxia
✓
C
Periosteal new bone formation secondary to recurrent haemolytic crises
D
Osteoclast activation from excess unconjugated bilirubin deposition in bone
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During fetal development, haematopoiesis migrates through a defined anatomical sequence. A medical student is asked to order these sites chronologically during human gestation. Which sequence is CORRECT?
A
Bone marrow → Liver → Yolk sac → Spleen
B
Liver → Yolk sac → Spleen → Bone marrow
C
Yolk sac → Liver → Spleen → Bone marrow
✓
D
Yolk sac → Spleen → Liver → Bone marrow
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A 35-year-old woman with known myelofibrosis presents with progressive abdominal distension. Imaging shows marked hepatosplenomegaly. Her haemoglobin is 6.9 g/dL and the peripheral smear shows tear-drop poikilocytes (dacrocytes). The pathophysiology of her splenomegaly is BEST explained by which mechanism?
A
Congestive splenomegaly from portal hypertension secondary to hepatic fibrosis
B
Reactivation of the fetal hepatosplenic haematopoietic programme to compensate for marrow failure
✓
C
Splenic sequestration of red cells causing secondary haemolytic anaemia
D
Lymphoid hyperplasia from recurrent infections in an immunocompromised state
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A 24-year-old medical intern is collecting blood from a febrile patient for: (1) blood cultures, (2) complete blood count, (3) coagulation screen (PT/aPTT), and (4) serum chemistry panel. Using the standard order-of-draw protocol, which sequence is CORRECT?
A
Blood culture → Purple (EDTA) → Blue (sodium citrate) → Red (plain)
B
Blood culture → Blue (sodium citrate) → Red (plain) → Purple (EDTA)
✓
C
Blue (sodium citrate) → Blood culture → Purple (EDTA) → Red (plain)
D
Purple (EDTA) → Blood culture → Blue (sodium citrate) → Red (plain)
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A sodium citrate (blue-top) tube is filled to only 70% of its required volume (instead of 100%). The sample is sent for PT and aPTT. Which of the following will MOST likely be reported by the coagulation laboratory?
A
Falsely shortened PT due to excess citrate consuming more calcium during recalcification
B
Falsely prolonged PT and aPTT due to excess anticoagulant relative to plasma volume
✓
C
Falsely elevated platelet count because platelets cluster in citrate-rich plasma
D
No significant change because the analyser automatically corrects for fill volume
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A laboratory technician receives an EDTA (purple-top) blood sample for a complete blood count. On visual inspection, the sample is clotted. Which combination of CBC results should be expected from this sample?
A
Falsely elevated platelets and elevated WBC count with normal haemoglobin
B
Spuriously low platelet count, distorted cell morphology, and an unreliable white cell differential
✓
C
Normal haemoglobin with falsely elevated MCV due to RBC swelling in fibrin network
D
Isolated false neutrophilia from neutrophil degranulation into the clot
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A phlebotomist draws blood from a 65-year-old diabetic patient for fasting glucose. The only available tube is a lithium heparin (green-top) tube. The sample is run on the hospital's glucose analyser. How will this anticoagulant affect the glucose result?
A
Heparin inhibits hexokinase and causes falsely LOW glucose values
B
Lithium heparin is acceptable for plasma glucose and will not significantly alter the result if processed promptly
✓
C
Heparin activates erythrocyte glycolysis causing rapid glucose consumption and falsely low values after 2 hours
D
Heparin causes haemolysis which releases intracellular glucose, falsely elevating the reading
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A peripheral blood smear is prepared from a patient who had blood collected 8 hours earlier and stored at room temperature in an EDTA tube. The smear shows swollen, vacuolated neutrophils with indistinct nuclear segments. The platelet count on the analyser is 90,000/µL, but a fresh recollection shows 210,000/µL. Which pre-analytical factor is MOST likely responsible for both findings?
A
EDTA-induced platelet satellitism causing both pseudothrombocytopenia and neutrophil rosette formation
B
Prolonged EDTA storage at room temperature causing cellular degradation and platelet clumping
✓
C
Lipid-mediated interference with the impedance method of platelet counting
D
Concurrent bacteraemia causing neutrophil toxic granulation and platelet consumption
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A clinical pathology department uses both the Sahli (acid haematin) method and the cyanmethemoglobin (Drabkin's) method for haemoglobin estimation. A quality assurance officer compares results. Which statement CORRECTLY differentiates the two methods for clinical use?
A
Sahli's method is more accurate for HbF and is preferred in neonatal units
B
Cyanmethemoglobin is the international reference method because it measures nearly all Hb forms with a coefficient of variation <2%
✓
C
Sahli's method is preferred for routine use because it requires no spectrophotometer
D
Both methods are equivalent and WHO recommends either for large-scale population surveys
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A 55-year-old man with polycythaemia vera has a haematocrit of 65%. A coagulation screen is ordered urgently. Standard sodium citrate (blue-top) tubes use a 1:9 citrate-to-blood ratio. The laboratory director advises adjusting the citrate volume. Which is the MOST appropriate action and reasoning?
A
Use a standard tube; haematocrit does not affect citrate ratio requirements
B
Reduce the volume of citrate in the tube because plasma volume is reduced in high-haematocrit samples, preventing excess citrate from prolonging clotting times
✓
C
Increase the citrate volume to compensate for the extra red cell mass
D
Substitute EDTA tube for coagulation testing in polycythaemia vera patients
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A 32-year-old woman is known to have hereditary spherocytosis (HS). She presents with a haemolytic crisis. Her CBC shows Hb 7.6 g/dL with a reticulocyte count of 22%. A junior intern interprets the reticulocyte count as indicating 'excellent marrow response' and advises no further investigation. Which critical error has the intern made?
A
The reticulocyte count in HS is always falsely elevated due to spherocyte interference with the analyser
B
The raw reticulocyte percentage must be corrected for anaemia severity to calculate the reticulocyte production index before interpreting marrow adequacy
✓
C
A reticulocyte count of 22% confirms the marrow is responding adequately and no further investigation is needed
D
In HS, the reticulocyte count reflects splenic destruction of immature red cells rather than marrow production
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