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PA16.1-3 | Welcome to Acquired Haemolytic Anaemias & Smear Morphology
Learning Objectives
- Classify acquired haemolytic anaemias by mechanism (immune vs. non-immune) and site of destruction (intravascular vs. extravascular).
- Describe the pathogenesis of warm and cold autoimmune haemolytic anaemia (AIHA), including the role of IgG, IgM, and complement.
- Explain the direct antiglobulin test (DAT/Coombs) — principle, interpretation, and clinical scenarios.
- Recognise diagnostic red-cell morphologies on peripheral smear: spherocytes, schistocytes, bite cells, and RBC agglutination.
- Outline the pathogenesis of microangiopathic haemolytic anaemia (MAHA) in TTP, HUS, and DIC.
- Describe the role of complement dysregulation in PNH and its diagnostic marker (CD55/CD59 by flow cytometry).
- Construct a diagnostic algorithm for a suspected haemolytic anaemia integrating DAT, smear morphology, LDH, and haptoglobin.
INSTRUCTIONS
Acquired haemolytic anaemias are encountered across specialties — from the emergency physician managing TTP to the physician encountering malaria. The unifying skill is pattern recognition: the peripheral blood smear and a single serological test (DAT) can narrow a broad differential to a specific mechanism within minutes. This module builds that skill systematically — mechanism first, morphology second, test interpretation third.
References
- Robbins & Kumar — Basic Pathology, 11th ed., Ch. 13 (Red Cell Disorders) (textbook)
- Harsh Mohan — Textbook of Pathology, 8th ed., Ch. 12 (textbook)
- Wintrobe's Clinical Hematology, 14th ed., Ch. 21–22 (textbook)
Version 2.0 | NMC CBUC 2024