Bleeding and Bruising

Introduction

Welcome to the comprehensive MCCQE1 study guide on bleeding and bruising. This resource is tailored for Canadian medical students preparing for the Medical Council of Canada Qualifying Examination Part I (MCCQE1). Understanding the mechanisms, diagnosis, and management of bleeding and bruising disorders is crucial for success in your MCCQE1 exam and future medical practice in Canada.

Key Concepts for MCCQE1

Definition and Pathophysiology

Bleeding is the escape of blood from the circulatory system, while bruising (ecchymosis) is the discoloration of skin due to blood leaking from damaged blood vessels into the surrounding tissues.

Normal Hemostasis

The process of normal hemostasis involves three main components:

1. Vascular spasm
2. Platelet plug formation
3. Coagulation cascade activation

Common Causes of Bleeding and Bruising

Understanding the etiology is crucial for MCCQE1 success. Here are the main categories:

1. Platelet disorders

   • Thrombocytopenia
   • Platelet function disorders

2. Coagulation factor deficiencies

   • Hemophilia A and B
   • Von Willebrand Disease

3. Vascular disorders

   • Ehlers-Danlos syndrome
   • Scurvy

4. Acquired disorders

   • Liver disease
   • Vitamin K deficiency
   • Disseminated Intravascular Coagulation (DIC)

5. Medication-induced

   • Anticoagulants (e.g., warfarin, heparin)
   • Antiplatelet drugs (e.g., aspirin, clopidogrel)

Canadian Epidemiology

Understanding the prevalence and incidence of bleeding disorders in Canada is essential for MCCQE1 preparation:

• Hemophilia A affects approximately 1 in 5,000 male births in Canada
• Hemophilia B affects approximately 1 in 30,000 male births
• Von Willebrand Disease is the most common inherited bleeding disorder, affecting up to 1% of the Canadian population

Diagnostic Approach

A systematic approach to diagnosing bleeding and bruising disorders is crucial for MCCQE1 success:

1. Detailed history

   • Family history of bleeding disorders
   • Medication history (anticoagulants, NSAIDs)
   • Dietary history (Vitamin K intake)

2. Physical examination

   • Assess for petechiae, ecchymoses, or hematomas
   • Evaluate for signs of underlying conditions (e.g., liver disease, malnutrition)

3. Laboratory tests

   • Complete Blood Count (CBC)
   • Prothrombin Time (PT) and International Normalized Ratio (INR)
   • Activated Partial Thromboplastin Time (aPTT)
   • Fibrinogen level
   • Specific factor assays as indicated

Management Principles

For MCCQE1 preparation, understand the general principles of managing bleeding and bruising disorders:

1. Treat the underlying cause
2. Replace deficient factors
3. Control active bleeding
4. Prevent complications

Canadian Guidelines for Management

The Association of Hemophilia Clinic Directors of Canada (AHCDC) provides guidelines for managing bleeding disorders. Key points include:

• Prophylactic factor replacement for severe hemophilia
• On-demand treatment for mild to moderate hemophilia
• Multidisciplinary care approach involving hematologists, nurses, physiotherapists, and social workers

Specific Disorders

Hemophilia A and B

Hemophilia is an X-linked recessive disorder causing deficiency in coagulation factors:

• Hemophilia A: Factor VIII deficiency
• Hemophilia B: Factor IX deficiency

Management in Canada:

• Factor replacement therapy
• Gene therapy trials (emerging treatment)

Von Willebrand Disease (vWD)

vWD is the most common inherited bleeding disorder in Canada, characterized by deficient or defective von Willebrand factor.

Types:

1. Type 1: Partial quantitative deficiency
2. Type 2: Qualitative defects
3. Type 3: Complete deficiency

Management:

• Desmopressin (DDAVP) for Type 1 and some Type 2
• Von Willebrand factor concentrates for Type 3 and severe cases

Immune Thrombocytopenia (ITP)

ITP is an acquired disorder characterized by immune-mediated destruction of platelets.

Canadian Approach:

• First-line: Corticosteroids or IVIG
• Second-line: Thrombopoietin receptor agonists (e.g., eltrombopag, romiplostim)
• Splenectomy considered for refractory cases

Key Points to Remember for MCCQE1

1. Understand the normal hemostatic process and how disorders disrupt it
2. Know the epidemiology of bleeding disorders in Canada
3. Be familiar with the diagnostic approach, including history, physical, and laboratory tests
4. Understand the principles of management and specific treatments for common disorders
5. Be aware of Canadian guidelines and unique aspects of care delivery in the Canadian healthcare system
6. Recognize the importance of multidisciplinary care in managing bleeding disorders

Sample MCCQE1-Style Question

A 25-year-old woman presents to her family physician with a history of easy bruising and prolonged bleeding after dental procedures. She mentions that her mother had similar issues. Physical examination reveals several ecchymoses on her arms and legs. Initial laboratory tests show normal platelet count, PT, and aPTT. Which one of the following is the most appropriate next step in management?

• A. Order factor VIII and IX assays
• B. Initiate oral iron supplementation
• C. Perform von Willebrand factor antigen and activity tests
• D. Start prophylactic factor replacement therapy
• E. Refer for platelet function testing

Explanation

The correct answer is:

• C. Perform von Willebrand factor antigen and activity tests

This patient's presentation is highly suggestive of von Willebrand Disease (vWD), the most common inherited bleeding disorder in Canada. The key features supporting this diagnosis are:

1. History of easy bruising and prolonged bleeding after procedures
2. Family history (mother with similar issues)
3. Normal platelet count, PT, and aPTT (which can be normal in vWD)

Von Willebrand Disease often presents with mucocutaneous bleeding and a positive family history. The normal PT, aPTT, and platelet count rule out many other bleeding disorders but do not exclude vWD.

The most appropriate next step is to perform specific tests for vWD, including von Willebrand factor antigen and activity tests. These tests will help confirm the diagnosis and determine the subtype of vWD, which is crucial for appropriate management.

Other options are less appropriate: A. Factor VIII and IX assays are more relevant for hemophilia, which is less likely given the patient's gender and normal aPTT. B. Iron supplementation is not indicated without evidence of iron deficiency anemia. D. Prophylactic factor replacement is not initiated without a confirmed diagnosis and is typically reserved for severe cases. E. Platelet function testing might be considered later but is not the most appropriate next step given the high suspicion for vWD.

Canadian Guidelines

The Association of Hemophilia Clinic Directors of Canada (AHCDC) provides comprehensive guidelines for the diagnosis and management of bleeding disorders. Key points include:

1. Emphasis on early diagnosis and prophylactic treatment for severe cases
2. Recommendation for comprehensive care through specialized hemophilia treatment centers
3. Promotion of home therapy programs for factor replacement
4. Regular monitoring and follow-up to prevent and manage complications

References

1. Srivastava A, Santagostino E, Dougall A, et al. WFH Guidelines for the Management of Hemophilia, 3rd edition. Haemophilia. 2020;26(S6):1-158.

2. Canadian Hemophilia Society. (2021). Bleeding Disorders. Retrieved from https://www.hemophilia.ca/bleeding-disorders/ (opens in a new tab)

3. Lillicrap D, James P. von Willebrand Disease: An Introduction for the Primary Care Physician. Treatment of Hemophilia, No. 47. World Federation of Hemophilia, 2009.

4. Neunert C, Lim W, Crowther M, et al. The American Society of Hematology 2011 evidence-based practice guideline for immune thrombocytopenia. Blood. 2011;117(16):4190-4207.

5. Association of Hemophilia Clinic Directors of Canada. (2020). Clinical Practice Guidelines. Retrieved from https://ahcdc.ca/clinical-practice-guidelines/ (opens in a new tab)

6. Bowman M, Hopman WM, Rapson D, Lillicrap D, James P. The prevalence of symptomatic von Willebrand disease in primary care practice. J Thromb Haemost. 2010;8(1):213-216.