I have unexplained bruising without trauma; what evaluation and management steps should I take?

Unexplained Bruising: Evaluation and Management

Begin with a detailed history focusing on bruise location, pattern, medication use, family bleeding history, and associated bleeding symptoms (nosebleeds, heavy menses, gum bleeding), followed by initial laboratory testing with CBC with platelet count, PT, aPTT, and fibrinogen level—but recognize that normal results do not exclude bleeding disorders, particularly von Willebrand disease or platelet function disorders. 1, 2, 3

Critical History Elements

Your history must distinguish between benign and pathologic causes:

• Bruise location matters significantly: Bruises over soft tissues (thighs, upper arms, trunk, back) are more concerning for bleeding disorders than those over bony prominences from normal activity 3
• Medication review is essential: Anticoagulants, antiplatelets, NSAIDs, steroids, SSRIs (particularly fluoxetine), and certain antibiotics increase bruising tendency 3, 4
• Family history: Ask specifically about bleeding disorders, easy bruising in relatives, excessive bleeding with surgeries or dental procedures 1, 3
• Associated bleeding symptoms: Mucocutaneous bleeding (nosebleeds, gum bleeding, heavy menses) suggests platelet or von Willebrand disease, while bleeding into deeper structures suggests coagulation factor deficiencies 5

Initial Laboratory Evaluation

Order these tests first 1, 2, 3:

• Complete blood count with platelet count: Identifies thrombocytopenia as a cause; review peripheral smear for platelet morphology 3
• PT (Prothrombin Time): Detects deficiencies in factors II, V, VII, X, and fibrinogen 1, 3
• aPTT (Activated Partial Thromboplastin Time): Detects deficiencies in factors VIII, IX, XI, XII, and common pathway factors 1, 3
• Fibrinogen level: Detects fibrinogen defects 3

Critical Pitfall to Avoid

Normal PT/aPTT does NOT rule out bleeding disorders—these tests miss von Willebrand disease (the most common inherited bleeding disorder, affecting 1 in 1,000 people), Factor XIII deficiency, and platelet function disorders 2, 3. If clinical suspicion remains high with normal screening tests, proceed to specialized testing.

Interpretation Algorithm

If PT and aPTT are both normal:

• High likelihood of von Willebrand disease or platelet function disorder 3
• Order von Willebrand disease panel: VWF antigen, VWF ristocetin cofactor activity, Factor VIII coagulant activity 3
• Consider platelet function studies if VWD testing is negative 3

If PT and/or aPTT are prolonged:

• Evaluate for liver disease, vitamin K deficiency, or DIC 3
• Check liver function tests, vitamin K level (or empiric trial of vitamin K), and DIC panel (D-dimer, fibrin degradation products) 3

If platelet count is low:

• Distinguish between decreased production vs. increased destruction by examining mean platelet volume and peripheral smear 5
• Consider immune thrombocytopenia (ITP), which is often self-resolving 3

If platelet count is normal or elevated:

• Do not assume platelets are functioning normally—qualitative platelet defects can cause significant bleeding despite normal or high counts 3
• Acquired von Willebrand syndrome can occur with high platelet counts 3

When to Refer to Hematology

Refer immediately if 1, 3:

• Initial screening tests are abnormal
• Specialized testing is needed (platelet aggregation studies, VWD multimer analysis, Factor XIII assay)
• Clinical suspicion remains high despite normal initial testing
• Patient requires preoperative clearance with history of easy bruising

Special Populations and Considerations

Children and Adolescents:

• Any bruising in non-mobile infants requires immediate evaluation for both abuse and bleeding disorders 2, 6
• In children, bruising patterns must be carefully evaluated to distinguish bleeding disorders from non-accidental trauma—a bleeding disorder does not exclude abuse 1
• If blood products have been transfused, delay bleeding disorder screening until transfused clotting elements are eliminated 1, 3

Elderly Patients:

• Senile purpura from age-related vascular and skin thinning is common and benign 3, 6

Connective Tissue Disorders:

• Ehlers-Danlos syndrome causes easy bruising through vascular fragility; standard coagulation tests are typically normal except for capillary fragility tests 3, 7

Laboratory Handling Considerations

Coagulation tests are extremely sensitive to specimen handling—false-positive results are common with inappropriate handling, so ensure testing is performed in experienced laboratories 1, 3. The aPTT can be falsely prolonged with lupus anticoagulant or Factor XII deficiency (which does not cause true bleeding) 1, 3.

Additional Causes to Consider

• Vitamin deficiencies: Vitamin K deficiency (prolonged PT) or scurvy/vitamin C deficiency (impaired collagen synthesis) 3, 6
• Liver disease/cirrhosis: Decreased clotting factor production 3, 6
• Malignancies: Can cause thrombocytopenia or coagulation abnormalities 3, 6
• DIC: Can cause any type of bruising or bleeding 3, 6