20 ASCP Hematology Practice Questions with Full Answers and Rationales

Below are fifteen worked ASCP-style haematology MCQs. Each item includes the correct answer, a full rationale, and an explanation of why every wrong option is wrong. Attempt each question before reading the explanation — active recall drives retention.

These are original questions written by MedLabPrep and are not official ASCP exam content.

Question 1 — IDA vs Anaemia of Chronic Disease

Which iron-study pattern is most consistent with iron-deficiency anaemia (IDA)?

• A. Low serum iron, low TIBC, high ferritin
• B. Low serum iron, high TIBC, low ferritin
• C. High serum iron, low TIBC, high ferritin
• D. Normal serum iron, low TIBC, low ferritin

Answer: B. IDA: iron stores are depleted (low ferritin), so transport capacity up-regulates (high TIBC). ACD shows low iron with normal/low TIBC and normal/high ferritin (acute-phase reactant). C and D describe non-physiologic patterns. (Rodak 6th ed.)

Question 2 — Intravascular haemolysis

Which lab finding is most specific for intravascular haemolysis?

• A. Elevated indirect bilirubin
• B. Elevated reticulocyte count
• C. Decreased haptoglobin with haemoglobinuria
• D. Elevated LDH

Answer: C. Free plasma haemoglobin binds haptoglobin, depleting it; excess spills into urine. Indirect bilirubin, retics, and LDH rise in both extra- and intravascular haemolysis and are therefore less specific. (Henry's 24th ed.)

Question 3 — Megaloblastic anaemia

Which peripheral-smear finding best supports megaloblastic anaemia?

• A. Basophilic stippling
• B. Target cells
• C. Hypersegmented neutrophils and oval macrocytes
• D. Spherocytes

Answer: C. Impaired DNA synthesis (B12/folate) produces oval macrocytes and hypersegmented (≥5 lobes) neutrophils. Stippling → lead/thalassaemia; targets → liver disease/HbC; spherocytes → hereditary spherocytosis/AIHA. (Rodak 6th ed.)

Question 4 — Sickle cell disease

Which HPLC pattern confirms sickle cell disease (HbSS)?

• A. HbA 60%, HbS 40%
• B. HbS 80-95%, HbF 2-20%, HbA 0%
• C. HbA 90%, HbA2 4%, HbF 1%
• D. HbS 45%, HbC 45%

Answer: B. Homozygous HbSS lacks HbA entirely. A describes sickle trait; C is a normal adult pattern; D is HbSC disease. (Rodak 6th ed.)

Question 5 — CLL immunophenotype

Which flow-cytometry profile is most typical for chronic lymphocytic leukaemia?

• A. CD10+, TdT+, CD19+
• B. CD5+, CD19+, CD23+, dim surface Ig
• C. CD3+, CD4+, CD8-
• D. CD34+, HLA-DR+, MPO+

Answer: B. CLL is a mature B-cell malignancy aberrantly co-expressing the T-cell antigen CD5. A = B-ALL; C = mature T-helper cells; D = AML blasts. (Henry's 24th ed.)

Question 6 — Leukaemoid reaction vs CML

Which finding best distinguishes CML from a leukaemoid reaction?

• A. WBC greater than 50 × 10⁹/L
• B. Left shift with myelocytes
• C. Low LAP score with t(9;22) BCR-ABL fusion
• D. Toxic granulation

Answer: C. CML shows a low leukocyte alkaline phosphatase score and the pathognomonic Philadelphia chromosome. Leukaemoid reactions show a HIGH LAP. A and B occur in both; toxic granulation favours reactive processes. (Rodak 6th ed.)

Question 7 — Auer rods

Auer rods on a peripheral smear are diagnostic of:

• A. Acute lymphoblastic leukaemia
• B. Acute myeloid leukaemia
• C. Chronic myeloid leukaemia
• D. Myelodysplastic syndrome

Answer: B. Auer rods are crystallised myeloperoxidase aggregates found in myeloblasts — specific for AML, especially APL (M3). (Rodak 6th ed.)

Question 8 — B-ALL flow cytometry

Which marker panel best supports B-lymphoblastic leukaemia?

• A. CD3+, CD7+, TdT+
• B. CD10+, CD19+, TdT+, HLA-DR+
• C. CD13+, CD33+, MPO+
• D. CD5+, CD19+, CD23+

Answer: B. B-ALL blasts express early B-cell antigens (CD19, CD10 aka CALLA) with the immature marker TdT. A = T-ALL; C = AML; D = CLL. (Henry's 24th ed.)

Question 9 — Reactive lymphocytes

Reactive (atypical) lymphocytes are classically associated with:

• A. Bacterial pneumonia
• B. Iron-deficiency anaemia
• C. Epstein-Barr virus infection
• D. Chronic myeloid leukaemia

Answer: C. EBV (infectious mononucleosis) drives a polymorphic reactive T-cell response — Downey cells. Bacterial infections show neutrophilia; IDA is microcytic anaemia; CML shows myeloid left shift. (Rodak 6th ed.)

Question 10 — PT/aPTT interpretation

Isolated prolongation of the PT with a normal aPTT points to a deficiency of:

• A. Factor VIII
• B. Factor IX
• C. Factor VII
• D. Factor XII

Answer: C. Factor VII is unique to the extrinsic pathway measured by PT. VIII, IX, XII are intrinsic-pathway factors affecting aPTT. (Henry's 24th ed.)

Question 11 — Mixing study

A prolonged aPTT that corrects on a 1:1 mix with normal plasma indicates:

• A. Lupus anticoagulant
• B. Factor VIII inhibitor
• C. Factor deficiency
• D. Heparin contamination

Answer: C. Correction indicates the patient is missing a factor supplied by the normal plasma. Failure to correct indicates an inhibitor. Heparin typically prolongs thrombin time as well. (Henry's 24th ed.)

Question 12 — D-dimer

D-dimer is most useful clinically as a:

• A. Diagnostic confirmation of DIC
• B. High-sensitivity rule-out test for VTE
• C. Marker of platelet activation
• D. Test of primary haemostasis

Answer: B. Its high negative predictive value makes D-dimer excellent for excluding DVT/PE in low-probability patients. A DIC panel includes multiple tests; D-dimer alone is not diagnostic. (Henry's 24th ed.)

Question 13 — Coulter (impedance) principle

Cell counting by the Coulter principle measures:

• A. Light scatter at multiple angles
• B. Fluorescence of stained nucleic acid
• C. Change in electrical impedance as a cell passes through an aperture
• D. Absorbance at 540 nm

Answer: C. Each cell traversing the aperture briefly interrupts current — pulse height correlates with cell volume. Light scatter is used by flow cytometers; absorbance measures Hgb. (Rodak 6th ed.)

Question 14 — Westgard 10x rule

The Westgard "10x" rule is violated when:

• A. One control result exceeds ±3 SD
• B. Two consecutive results exceed the same ±2 SD limit
• C. Ten consecutive results fall on the same side of the mean
• D. The range between duplicates exceeds 4 SD

Answer: C. 10x detects systematic bias (shift), not random error. A = 1_3s; B = 2_2s; D = R_4s. (Henry's 24th ed.)

Question 15 — Corrected reticulocyte count

A patient has Hct 21% (reference 45%) and a raw reticulocyte count of 6%. The corrected reticulocyte count is closest to:

• A. 1.4%
• B. 2.8%
• C. 6.0%
• D. 12.9%

Answer: B. Corrected retic = raw retic × (patient Hct / normal Hct) = 6 × (21/45) = 2.8%. Correction prevents overestimating marrow response in anaemic patients. (Rodak 6th ed.)

Next steps

If you missed more than four items, prioritise haematology in your next study block. Focus on morphology (atlas review), the coagulation cascade, and leukaemia immunophenotyping.