What causes easy bruising?

Causes of Easy Bruising

Easy bruising results from bleeding disorders (most commonly von Willebrand disease), medications, vascular/connective tissue disorders, vitamin deficiencies, or underlying systemic diseases—with the diagnostic approach guided by patient age, bleeding history, and initial laboratory screening. 1

Primary Bleeding Disorders

Von Willebrand disease is the most common inherited bleeding disorder (prevalence 1 in 1000), presenting with mucocutaneous bleeding and easy bruising, yet it is not detected by standard PT/aPTT screening. 1

Other Coagulation Disorders:

• Hemophilia (Factor VIII or IX deficiency) causes significant bruising even with mild deficiencies, particularly in males, and mild cases may not prolong aPTT. 1
• Factor XIII deficiency produces significant bruising but is missed by standard PT/aPTT screening tests. 1
• Platelet function disorders present with bruising and mucocutaneous bleeding, requiring specialized testing like platelet aggregation studies for diagnosis. 1
• Immune thrombocytopenia (ITP) is a transient, often self-resolving disorder characterized by low platelet count. 1

Medication-Related Causes

Anticoagulants, antiplatelets, NSAIDs, steroids, and certain antibiotics increase bruising tendency and must be documented in the medication history. 1

Vascular and Connective Tissue Disorders

• Ehlers-Danlos syndrome causes easy bruising in all subtypes due to capillary fragility and perivascular connective tissue weakness; the vascular subtype (collagen type III defect) can cause extensive bruising, spontaneous arterial rupture, and life-threatening internal bleeding. 2
• Senile purpura results from age-related thinning of blood vessels and skin. 1
• Arteriovenous malformations can produce localized bleeding and bruising. 1

Vitamin Deficiencies and Systemic Diseases

• Vitamin K deficiency is particularly critical in infants without prophylaxis at birth, presenting with prolonged PT and possibly aPTT. 1
• Liver disease/cirrhosis decreases clotting factor production, causing spontaneous bruising. 1
• Disseminated intravascular coagulation (DIC) can cause any pattern of bruising/bleeding including intracranial hemorrhage. 1
• Malignancies and infiltrative disorders produce thrombocytopenia or coagulation abnormalities. 1

Diagnostic Algorithm

Initial Laboratory Screening:

• Complete blood count with platelet count to evaluate for thrombocytopenia. 1
• PT and aPTT detect most factor deficiencies but miss von Willebrand disease and Factor XIII deficiency. 1
• Fibrinogen concentration and thrombin time detect fibrinogen defects. 1

When Standard Tests Are Normal:

In patients with normal PT/aPTT but persistent easy bruising, platelet function disorders or von Willebrand disease must be considered, requiring specialized testing including von Willebrand factor assays and platelet aggregation studies. 3

Historical Red Flags:

• Significant bleeding after circumcision, surgery, dental procedures, or from umbilical stump increases probability of bleeding disorder. 4
• Family history of bleeding disorders or ethnicity with higher rates of specific disorders necessitates targeted testing. 4
• Mucocutaneous bleeding (epistaxis, gum bleeding) suggests platelet dysfunction, while hemarthroses or deep hematomas indicate coagulopathy. 3

Critical Pitfalls to Avoid

Assuming normal PT/aPTT rules out bleeding disorders is incorrect—these tests miss von Willebrand disease, Factor XIII deficiency, and platelet function disorders. 1

In children, bruising location and pattern must distinguish between bleeding disorders and potential abuse: bruising on buttocks, ears, and genitals has higher specificity for abuse, while bruising at clothing pressure sites or infant seat fastener patterns may indicate bleeding disorders. 4

Referral to hematology is warranted when initial testing fails to reveal etiology in patients with high clinical suspicion for bleeding disorder. 3