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Hemophilia A & B

Hemophilia A and B are inherited bleeding disorders caused by deficiencies of clotting factors VIII and IX, respectively. They cause impaired secondary hemostasis and typically present with deep tissue bleeding, hemarthroses, and prolonged bleeding after trauma or procedures

Also called

Factor VIII & Factor IX Deficiency

ICD-10

D66- D67

Specialty

Hematology

Onset

Chronic

Reviewed

August 2026

On This Page

Overview

Hemophilia A is caused by factor VIII deficiency, while Hemophilia B is caused by factor IX deficiency. Both are usually X-linked recessive disorders, so they predominantly affect males. The severity depends on the residual clotting factor activity.

Etiology & Risk Factors

-Etiology

Hemophilia A

Caused by mutations in the F8 gene, resulting in reduced or absent factor VIII activity.

Hemophilia B

Caused by mutations in the F9 gene, resulting in reduced or absent factor IX activity.

Inheritance

Both are usually:

  • X-linked recessive

  • Mainly affect males

  • Females may be carriers

  • Rarely, females can have clinically significant disease

-Risk Factors

  • Family history

  • Maternal carrier status

  • Male sex

  • De novo mutation

  • Consanguinity may be relevant in rare familial cases

Pathophysiology

Factor VIII or IX deficiency → impaired intrinsic coagulation pathway → reduced activation of factor X → reduced thrombin generation → inadequate fibrin formation → defective secondary hemostasis → prolonged bleeding and recurrent bleeding into joints, muscles, and deep tissues.

Clinical Presentation

-Symptoms

  • Easy bruising

  • Prolonged bleeding after injury

  • Prolonged bleeding after surgery

  • Recurrent joint bleeding

  • Muscle hematomas

  • Nosebleeds

  • Oral bleeding

  • Hematuria

  • Gastrointestinal bleeding

Hemarthrosis

Commonly affects:

  • Knees

  • Ankles

  • Elbows

Repeated hemarthroses can cause chronic hemophilic arthropathy.

-Severe Disease

Severe hemophilia may present during infancy or early childhood with:

  • Spontaneous bleeding

  • Joint bleeding

  • Muscle hematomas

  • Intracranial hemorrhage

History Taking

-Ask about:

  • Previous bleeding episodes
  • Joint swelling or pain
  • Muscle hematomas
  • Prolonged bleeding after dental procedures
  • Surgical bleeding
  • Bleeding after circumcision
  • Intracranial bleeding
  • Hematuria
  • Family history
  • Maternal carrier status
  • Previous factor replacement
  • Inhibitor development

Physical Examination

-General Examination

Look for:

  • Pallor

  • Bruising

  • Signs of anemia

-Joint Examination

Assess for:

  • Swelling

  • Warmth

  • Tenderness

  • Reduced range of motion

  • Chronic joint deformity

Common joints:

  • Knee

  • Ankle

  • Elbow

-Muscle Examination

Look for:

  • Muscle swelling

  • Tenderness

  • Reduced movement

  • Signs of compartment syndrome

-Neurological Examination

Assess urgently for:

  • Headache

  • Altered consciousness

  • Focal neurological deficits

  • Signs of intracranial hemorrhage

Investigations

-Complete Blood Count

Usually:

  • Platelet count: normal

  • Hemoglobin may be reduced if significant bleeding has occurred

PT

Usually: Normal

aPTT Typically: Prolonged

Mixing Study

A prolonged aPTT that corrects with normal plasma supports a clotting factor deficiency.

Failure to correct suggests an inhibitor.

Factor Assays

  • Low factor VIII → Hemophilia A

  • Low factor IX → Hemophilia B

Inhibitor Testing

Patients receiving repeated factor replacement may develop factor VIII or IX inhibitors.

-The Bethesda assay can quantify inhibitor levels.

-Genetic Testing

Can identify the causative mutation and is useful for:

  • Confirming diagnosis

  • Carrier testing

  • Family counseling

  • Prenatal diagnosis

Diagnosis

Diagnosis is based on:

  • Compatible bleeding history
  • Family history
  • Prolonged aPTT
  • Normal PT
  • Normal platelet count
  • Reduced factor VIII or IX activity
  • Genetic testing when required
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Related Topics

Management

1. Factor Replacement

Hemophilia A

Replace factor VIII.

Options include:

  • Recombinant factor VIII

  • Extended half-life factor VIII preparations

Hemophilia B

Replace factor IX.

Options include:

  • Recombinant factor IX

  • Extended half-life factor IX preparations

Factor replacement is used for:

  • Acute bleeding

  • Surgical procedures

  • Trauma

  • Prevention of recurrent bleeding

2. Emicizumab

Used primarily for Hemophilia A, particularly for routine prophylaxis.

It is a bispecific antibody that mimics the function of factor VIII in the coagulation pathway.

3. Desmopressin

Useful in selected patients with:

  • Mild Hemophilia A

It increases endogenous factor VIII and von Willebrand factor.

It is not useful for Hemophilia B.

4. Antifibrinolytic Therapy

Examples:

  • Tranexamic acid

  • Aminocaproic acid

Particularly useful for:

  • Dental procedures

  • Oral bleeding

  • Mucosal bleeding

5. Inhibitors

If significant factor inhibitors develop, management may include:

  • Bypassing agents

  • Emicizumab for Hemophilia A

  • Immune tolerance induction in selected patients

Complications

  • Recurrent hemarthrosis
  • Chronic hemophilic arthropathy
  • Muscle hematomas
  • Intracranial hemorrhage
  • Gastrointestinal bleeding
  • Urinary tract bleeding
  • Compartment syndrome
  • Inhibitor development
  • Transfusion-related complications in older treatment eras
  • Chronic pain
  • Disability

Prognosis

With modern factor replacement, prophylaxis, and comprehensive specialist care, people with hemophilia can have near-normal life expectancy and good quality of life. The major long-term concerns are recurrent bleeding, joint damage, and development of factor inhibitors.

Key Points / Clinical Pearls

  • Hemophilia A = factor VIII deficiency.
  • Hemophilia B = factor IX deficiency.
  • Both are usually X-linked recessive.
  • They cause deep tissue bleeding and hemarthrosis.
  • PT is normal.
  • aPTT is prolonged.
  • Platelet count is usually normal.
  • Factor assays confirm the deficient clotting factor.
  • Hemophilia A may respond to desmopressin when mild.
  • Emicizumab is an important prophylactic option for Hemophilia A.
  • Hemophilia B is treated with factor IX replacement.
  • Inhibitors are an important complication of factor replacement.
  • Early treatment of bleeding helps prevent permanent joint damage.
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