AIM • STEP 10
Student Memory Support
Hemostasis, Platelet Disorders, von Willebrand Disease, Hemophilia and DIC
3rd Year MBBS • Multisystem • High-yield memory reinforcement and last-minute revision
Structured according to the supplied AIM Step 10 requirements. :contentReference[oaicite:0]{index=0}
1. High-Yield Flashcards
Tap each question to reveal the answer.
Q: What is the main difference between primary and secondary hemostasis?
A: Primary hemostasis forms the platelet plug; secondary hemostasis stabilizes it with fibrin.
Q: What are the two major hemostatic functions of von Willebrand factor?
A: It mediates platelet adhesion and stabilizes circulating factor VIII.
Q: What are the major mechanisms causing thrombocytopenia?
A: Reduced production, increased destruction, increased consumption, splenic sequestration and dilution.
Q: What is the basic mechanism of immune thrombocytopenia?
A: IgG autoantibodies coat platelet glycoproteins, leading mainly to splenic macrophage clearance.
Q: What laboratory pattern supports uncomplicated ITP?
A: Isolated thrombocytopenia with generally normal PT and aPTT.
Q: Which two disorders are the major thrombotic microangiopathies?
A: Thrombotic thrombocytopenic purpura and hemolytic uremic syndrome.
Q: How are the three major types of von Willebrand disease classified?
A: Type 1: partial quantitative deficiency; Type 2: qualitative defect; Type 3: severe quantitative deficiency.
Q: Which investigations are important in suspected von Willebrand disease?
A: vWF antigen, vWF activity and factor VIII activity, together with screening coagulation tests.
Q: Which factors are deficient in hemophilia A and hemophilia B?
A: Hemophilia A is factor VIII deficiency; hemophilia B is factor IX deficiency.
Q: What bleeding pattern is typical of hemophilia?
A: Deep tissue bleeding, muscle hematomas and recurrent hemarthroses.
Q: What is the typical screening coagulation pattern in hemophilia?
A: Prolonged aPTT with generally normal PT and platelet count.
Q: What is the central pathological event in DIC?
A: Systemic coagulation activation with excessive thrombin generation and widespread fibrin formation.
Q: What is the characteristic morphological lesion in DIC?
A: Widespread fibrin-rich microthrombi in small vessels and capillaries.
Q: Which laboratory pattern supports DIC?
A: Thrombocytopenia, prolonged PT/aPTT, reduced fibrinogen and increased D-dimer or fibrin degradation products.
Q: How do tranexamic acid and aminocaproic acid reduce bleeding?
A: They inhibit fibrinolysis and reduce plasmin-mediated breakdown of fibrin clots.
Q: Why can desmopressin help selected patients with mild hemophilia A?
A: It increases release of endogenous vWF and factor VIII.
Q: What is the role of oprelvekin in thrombocytopenia?
A: Recombinant IL-11 stimulates megakaryocyte development and increases platelet production.
Q: Which treatments are important in symptomatic immune thrombocytopenia?
A: Corticosteroids reduce immune destruction; IVIG can raise platelets rapidly, while platelet transfusion is reserved for major bleeding.
2. Mnemonics
Mnemonic Title:
Major Mechanisms of Thrombocytopenia
Mnemonic Word:
PICS-D
Meaning:
Production reduced • Immune destruction • Consumption • Splenic sequestration • Dilution
Mnemonic Title:
von Willebrand Disease Types
Mnemonic Word:
1 = Less, 2 = Faulty, 3 = Very Little
Meaning:
Type 1 = partial quantitative deficiency • Type 2 = qualitative dysfunction • Type 3 = severe quantitative deficiency.
Mnemonic Title:
DIC Laboratory Pattern
Mnemonic Word:
P-F-D
Meaning:
Platelets fall • Fibrinogen falls • D-dimer rises, with prolongation of coagulation tests.
3. Memory Tables
Platelet/vWF Disorder vs Hemophilia
| Feature | Platelet / vWF Pattern | Hemophilia Pattern |
|---|---|---|
| Bleeding | Petechiae, mucosal bleeding | Deep bleeding, hemarthrosis |
| Main defect | Primary hemostasis | Secondary hemostasis |
| Platelet count | Low in thrombocytopenia; usually normal in vWD | Normal |
| aPTT | May rise in significant vWD | Prolonged |
Hemophilia A vs Hemophilia B
| Feature | Hemophilia A | Hemophilia B |
|---|---|---|
| Deficient factor | Factor VIII | Factor IX |
| Pathway | Intrinsic | Intrinsic |
| Confirmation | Factor VIII assay | Factor IX assay |
| Direct replacement | Factor VIII | Factor IX |
| Desmopressin | Useful in selected mild disease | Does not correct factor IX deficiency |
4. Rapid Revision Points — Last-Minute Revision
Must Remember:
- vWF connects exposed collagen to platelet GPIb during platelet adhesion.
- Activated platelet GPIIb/IIIa binds fibrinogen to produce aggregation.
- ITP is primarily a peripheral immune platelet-destruction disorder.
- TTP and HUS are major thrombotic microangiopathies.
- Type 2 vWD is a qualitative vWF abnormality.
- Hemophilia A and B affect factors VIII and IX of the intrinsic pathway.
- Recurrent hemarthrosis strongly favors a coagulation-factor defect over a platelet disorder.
- DIC combines microvascular thrombosis with consumption-related bleeding.
- Antifibrinolytics preserve formed fibrin; they do not replace the missing factor in hemophilia.
- Oprelvekin supports platelet production through megakaryocyte stimulation.
KMU Exam Trap: Petechiae and mucosal bleeding point toward primary-hemostasis disorders; deep muscle bleeding and hemarthrosis point toward secondary-hemostasis defects.
5. Clinical Memory Hooks
Petechiae + mucosal bleeding + isolated low platelets → immune thrombocytopenia
Recurrent epistaxis + normal platelet count + abnormal vWF testing → von Willebrand disease
Boy with recurrent hemarthrosis + prolonged aPTT → hemophilia → confirm with factor assay
Mild hemophilia A before a minor procedure → desmopressin → increased endogenous vWF and factor VIII
Sepsis or major tissue injury + bleeding + prolonged PT/aPTT + high D-dimer → disseminated intravascular coagulation
6. Starred High-Yield Exam Points
- ⭐ ITP: IgG-mediated platelet destruction → isolated thrombocytopenia with generally normal PT and aPTT.
- ⭐ vWD: vWF defect impairs platelet adhesion and may reduce factor VIII activity.
- ⭐ Hemophilia A = factor VIII deficiency; hemophilia B = factor IX deficiency.
- ⭐ Hemophilia: prolonged aPTT + normal PT + deep bleeding/hemarthrosis.
- ⭐ DIC: fibrin microthrombi + platelet/factor consumption + secondary fibrinolysis.
- ⭐ DIC laboratory clue: thrombocytopenia, prolonged coagulation tests, low fibrinogen and raised D-dimer.
- ⭐ Desmopressin can help selected mild hemophilia A, while factor IX deficiency requires factor IX replacement.