FCPS Part 1 haematology: the high-yield guide
Haematology questions reward a few sorting tools: the MCV, the reticulocyte count, PT and APTT, and a short list of translocations. Here is each one with the stories examiners use.
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Sorting tools, not lists
Haematology looks like a long subject, but the questions lean on a few sorting tools. If you know which tool to reach for, the answer usually falls out:
- Anaemia? Start with the MCV, then the reticulocyte count.
- Bleeding? Start with the platelet count, PT and APTT.
- Malignancy? Start with the cell on the film or the translocation.
Anaemia by MCV
| Small cells (microcytic) | Normal-sized cells | Large cells (macrocytic) |
|---|---|---|
| Iron deficiency | Acute blood loss | B12 or folate deficiency (megaloblastic) |
| Thalassaemia trait | Anaemia of chronic disease (often) | Alcohol |
| Anaemia of chronic disease (later) | Haemolysis | Liver disease, hypothyroidism |
| Sideroblastic anaemia (including lead) | Kidney disease | Haemolysis (from reticulocytes) |
Telling the microcytic anaemias apart
| Test | Iron deficiency | Thalassaemia trait | Chronic disease |
|---|---|---|---|
| Ferritin | Low | Normal | Normal or high |
| TIBC | High | Normal | Low |
| Red cell count | Low | Normal or high for the Hb | Low |
| Clue | Pica, heavy periods, worms | Family history; raised HbA2 in beta trait | Chronic infection or inflammation |
Iron deficiency is the commonest anaemia in Pakistan, and the exam knows it. A toddler who eats soil, with an MCV of 62 and a low ferritin, is not a thalassaemia question.
Lead poisoning (old paint, some traditional remedies and cosmetics) gives a microcytic anaemia with basophilic stippling. Lead blocks ALA dehydratase and ferrochelatase.
Haemolysis
A low haemoglobin with raised unconjugated bilirubin, raised LDH, low haptoglobin and a high reticulocyte count is haemolysis. A reticulocyte count of 10% tells you the marrow is working hard, so the problem is destruction or loss, not production.
| Condition | Key fact |
|---|---|
| Hereditary spherocytosis | Defect in spectrin or ankyrin; spherocytes; Coombs negative; splenectomy helps |
| G6PD deficiency | Haemolysis after oxidant drugs (primaquine, dapsone, sulfonamides) or fava beans; Heinz bodies and bite cells |
| Autoimmune haemolysis | Coombs positive |
| Beta-thalassaemia major | Transfusion-dependent from infancy; iron overload needs chelation |
Thalassaemia is common in Pakistan, and family screening before marriage is a real public health issue. Expect it in both pathology and community medicine questions.
Bleeding: PT, APTT and the platelets
| Test | Measures | Prolonged by |
|---|---|---|
| PT (INR) | Extrinsic pathway (factor VII) and the common pathway | Warfarin, liver disease, vitamin K deficiency |
| APTT | Intrinsic pathway (XII, XI, IX, VIII) and the common pathway | Heparin, haemophilia |
| Platelet count and function | Primary haemostasis | Thrombocytopenia, von Willebrand disease, aspirin |
| Disorder | Pattern |
|---|---|
| Haemophilia A (factor VIII) and B (factor IX) | Joint and muscle bleeds; prolonged APTT; normal PT and platelets; X-linked |
| Von Willebrand disease | Mucosal bleeding; prolonged bleeding time; APTT may be prolonged |
| Bernard-Soulier syndrome | Defective adhesion (GpIb); large platelets; mildly low count |
| Glanzmann thrombasthenia | Defective aggregation (GpIIb/IIIa); normal count |
| DIC | PT and APTT prolonged, platelets and fibrinogen low, D-dimer high |
A boy with joint bleeds, a prolonged APTT and a normal factor VIII has haemophilia B. The question gives you the normal VIII result to stop you answering haemophilia A on reflex.
Factor XII starts the intrinsic pathway when blood touches a negatively charged surface. The body's own anticoagulants include heparin (from mast cells), antithrombin, and proteins C and S.
Blood products
- Cryoprecipitate: fibrinogen, factor VIII, von Willebrand factor and factor XIII. In a bleeding haemophiliac when factor VIII concentrate is not available, cryoprecipitate (or fresh frozen plasma) is the answer.
- Fresh frozen plasma: all the clotting factors.
- Warfarin with major bleeding or a very high INR: intravenous vitamin K plus prothrombin complex concentrate.
- Tranexamic acid: blocks fibrinolysis. Used in trauma and postpartum haemorrhage.
TTP, HUS and ITP
- TTP: fever, confusion, low platelets, fragmented red cells (schistocytes) and kidney injury, from low ADAMTS13 activity. Platelet transfusion is avoided; plasma exchange is the treatment.
- HUS: a child after bloody diarrhoea (E. coli O157), with kidney failure, low platelets and haemolysis.
- ITP: isolated low platelets with purpura in a well patient. Steroids first.
Leukaemia and lymphoma: the translocations
| Translocation | Disease | What to link it with |
|---|---|---|
| t(9;22), Philadelphia chromosome | Chronic myeloid leukaemia | BCR-ABL; imatinib; massive splenomegaly |
| t(15;17) | Acute promyelocytic leukaemia | Auer rods, DIC; treated with all-trans retinoic acid |
| t(14;18) | Follicular lymphoma | BCL-2 (blocks apoptosis) |
| t(8;14) | Burkitt lymphoma | MYC; "starry sky" pattern |
| t(11;14) | Mantle cell lymphoma | Cyclin D1 |
Hodgkin lymphoma: Reed-Sternberg cells with "owl-eye" nucleoli, CD15 and CD30 positive. Nodular sclerosis is the commonest type. Among the classical types, lymphocyte-rich carries the best prognosis.
Multiple myeloma: the CRAB picture (calcium raised, renal failure, anaemia, bone pain) with rouleaux on the film. Serum protein electrophoresis showing an M band is the first test.
Massive splenomegaly (reaching the right iliac fossa): chronic myeloid leukaemia, myelofibrosis, chronic malaria and visceral leishmaniasis (kala-azar), which is seen in parts of northern Pakistan.
Blood groups and transfusion
- Anti-D is IgG, so it crosses the placenta and causes haemolytic disease of the newborn. Anti-A and anti-B are mostly IgM, which does not cross.
- IgG is the only immunoglobulin that crosses the placenta.
- For an exchange transfusion in Rh disease, the blood is group O, Rh-negative, crossmatched against the mother's serum.
| Reaction | Timing | Clue |
|---|---|---|
| Acute haemolytic (ABO mismatch) | Minutes | Fever, loin pain, hypotension, dark urine. Stop the transfusion immediately |
| Febrile non-haemolytic | During or soon after | Fever only; the commonest reaction |
| Anaphylaxis | Minutes | Classically in IgA deficiency |
| TRALI | Within 6 hours | Breathlessness with a normal or low JVP |
| Circulatory overload (TACO) | Within hours | Breathlessness with raised JVP and hypertension |
Physiology that shows up in haematology
- The strongest stimulus for erythropoietin is tissue hypoxia sensed in the kidney.
- After a large bleed, plasma volume recovers within days, but red cell mass is the last to return to normal (weeks).
- In pregnancy, plasma volume rises more than red cell mass, so haemoglobin falls slightly. If the MCV and ferritin are normal, that fall is physiological.
- A haematocrit of 41% means 41% of the blood volume is red cells.
How to revise haematology
- Learn the three sorting tools: MCV, reticulocyte count, and PT with APTT.
- Learn the translocation table.
- Do mixed haematology questions and, for each one, name the sorting tool you used before checking the answer.
Practise these in the FCPS-1 Prep question bank. The explanations show why each wrong anaemia or bleeding disorder does not fit.
Read next: Pathology high-yield · Physiology high-yield · Microbiology high-yield
Frequently asked questions
Is haematology part of pathology or medicine in FCPS Part 1?
Haematopathology is part of pathology, and the blood physiology part is in physiology. Both appear in Paper 1.
How many translocations do I need?
The five in the table cover what is usually asked. Add more only once those are automatic.
Do I need to learn transfusion volumes and doses?
Not for Part 1. Know which product contains what, and the transfusion reactions.