What are the potential causes of skin bruising in a 17-year-old female?

Causes of Skin Bruising in a 17-Year-Old Female

In a 17-year-old female presenting with skin bruising, the primary diagnostic considerations are von Willebrand disease (VWD), medication effects (particularly anticoagulants and antiplatelet agents), platelet disorders, connective tissue disorders like Ehlers-Danlos syndrome, and trauma (including non-accidental injury). 1, 2, 3

Initial Clinical Assessment

History Taking

• Bleeding symptoms: Specifically assess for significant bleeding after surgery, epistaxis, joint hemorrhages, prolonged bleeding from cuts, increased menstrual flow, or gum bleeding from brushing 2, 4
• Medication review: Document all medications including over-the-counter drugs (especially aspirin, NSAIDs), anticoagulants (warfarin causes hemorrhage as a direct consequence of anticoagulant effect), and herbal/botanical products 2, 4
• Family history: Evaluate for specific bleeding disorders or ethnicity associated with higher rates of certain bleeding disorders 2
• Trauma history: Determine if bruising pattern is explained by reported trauma; at 17 years, bruising should correlate with normal activity patterns 2, 5

Physical Examination Findings

• Bruise location and pattern: In normal adolescents, bruises are most frequently on lower limbs (shins and knees); bruising on thorax, abdomen, pelvis, buttocks, chin, ears, or neck occurs in <2% of normal children and warrants further investigation 5
• Number of bruises: While 76.6% of normal children >9 months have at least one recent injury, ≥15 injuries is unusual and requires evaluation 5
• Associated findings: Look for signs of Ehlers-Danlos syndrome (skin hyperextensibility, joint hypermobility), scurvy, cancer, or arteriovenous malformations 2, 3

Laboratory Evaluation

Initial Screening Panel

Order the following tests simultaneously: 2

• Complete blood count (CBC) with platelet count and peripheral blood smear
• Prothrombin time (PT)
• Activated partial thromboplastin time (aPTT)
• Fibrinogen level (if PT or aPTT abnormal)

Critical Diagnostic Consideration

A common diagnostic trap is assuming that normal PT and aPTT rule out bleeding disorders—these tests detect only about 50% of coagulation disorders and do NOT reliably detect von Willebrand disease or factor XIII deficiency. 1, 2

Specific Testing for Von Willebrand Disease

If there is spontaneous and recurrent bruising, even with only mildly prolonged aPTT or completely normal basic coagulation tests, specific VWD testing must be performed: 1

• Von Willebrand antigen
• Ristocetin cofactor activity
• Factor VIII coagulant activity

These tests should be ordered simultaneously, as VWD often does not significantly prolong aPTT and represents the most likely diagnosis in adolescent females with mucocutaneous bleeding patterns. 1

Additional Considerations

• Acquired von Willebrand syndrome (AVWS): Consider this diagnosis when there is no personal or family history of bleeding, suggesting an acquired rather than hereditary process 1
• Mild factor VIII or IX deficiency: May not significantly prolong aPTT but can cause spontaneous bruising 1
• Platelet function testing: The platelet function analyzer (PFA-100) can screen for platelet disorders but has limitations; consultation with hematology is recommended for interpretation 2

Differential Diagnosis by Category

Hematologic Causes

• Von Willebrand disease (most common inherited bleeding disorder in females) 1, 2
• Platelet disorders (thrombocytopenia, platelet function defects) 2
• Mild factor deficiencies 1
• Acquired coagulation inhibitors (rare but can cause spontaneous bleeding) 6

Medication-Related

• Warfarin (causes hemorrhage including unusual bleeding or bruising as adverse effect) 4
• Antiplatelet agents (aspirin, NSAIDs) 2, 4
• Herbal/botanical products 2, 4

Connective Tissue Disorders

• Ehlers-Danlos syndrome: Easy bruising present in all subtypes due to capillary fragility and perivascular connective tissue fragility; vascular subtype can cause extensive bruising 3
• Note: Hematological studies including clotting factors and platelet aggregation are usually normal in EDS except for the Hess test (Rumple-Leede test) indicating capillary fragility 3

Other Causes

• Actinic purpura (though typically in elderly, not 17-year-olds) 7
• Nutritional deficiencies (vitamin K, vitamin C/scurvy) 2
• Trauma (accidental or non-accidental) 2, 5

Management Pending Diagnosis

While awaiting specialized test results: 1

• Avoid NSAIDs and antiplatelet agents
• Postpone invasive procedures until definitive diagnosis
• Avoid activities that may result in traumatic injury 4

Referral Indications

Refer to hematology when: 2

• Initial laboratory evaluation indicates a bleeding disorder
• High clinical suspicion remains despite normal laboratory workup
• Specialized testing (VWD panel, platelet function testing) is needed
• Complex cases require expert interpretation