Bruising on Skin After Itching
Direct Answer
Bruising after itching (trauma-induced purpura) occurs when scratching causes capillary rupture in the dermis, and this is significantly exacerbated in patients with bleeding disorders or those taking anticoagulant/antiplatelet medications that impair normal hemostasis. 1, 2
Mechanism and Risk Factors
The mechanical trauma from scratching creates sufficient force to rupture small blood vessels in the skin. In patients with normal hemostasis, this typically produces minimal or no visible bruising. However, several factors dramatically increase bruising susceptibility:
High-Risk Medications
- Anticoagulants (warfarin, DOACs, heparin) and antiplatelet agents (aspirin, clopidogrel) impair coagulation and platelet function, making even minor trauma from scratching produce visible ecchymoses 1, 2
- NSAIDs, corticosteroids, and certain antibiotics can increase bruising tendency through various mechanisms affecting platelet function and vascular integrity 2
Underlying Bleeding Disorders
- Von Willebrand disease (most common inherited bleeding disorder, prevalence 1 in 1,000) presents with mucocutaneous bleeding and easy bruising; notably, it is not detected by standard PT/aPTT screening 3, 2
- Platelet function disorders can cause significant bruising despite normal platelet counts, requiring specialized testing like platelet aggregation studies 2
- Factor deficiencies (hemophilia, Factor XIII deficiency) may present with excessive bruising from minor trauma 2
Other Medical Conditions
- Liver disease/cirrhosis decreases clotting factor production 2
- Chronic kidney disease affects platelet function 1
- Vitamin K deficiency impairs synthesis of factors II, VII, IX, and X 4
- Senile purpura from age-related vascular and skin thinning 2
- Ehlers-Danlos syndrome and other connective tissue disorders affecting vascular integrity 1
Clinical Evaluation Algorithm
History Elements to Document
- Medication review: All anticoagulants, antiplatelets, NSAIDs, steroids, and alternative therapies 1, 2
- Personal bleeding history: Excessive bleeding after dental procedures, surgeries, circumcision, or menorrhagia 1, 3
- Family history: Maternal inheritance pattern particularly suggests von Willebrand disease 3
- Other bleeding sites: Nosebleeds, gum bleeding, hematuria, or gastrointestinal bleeding 1, 5
Physical Examination Findings
- Mucocutaneous bleeding (petechiae, gingival bleeding, epistaxis) suggests platelet dysfunction or von Willebrand disease 5, 6
- Hemarthroses or deep hematomas suggest coagulopathy (factor deficiencies) 5
- Bruise pattern and location: Diffuse petechiae at pressure points or clothing lines may indicate severe bleeding disorder 1
Laboratory Evaluation
Initial Screening Tests
When history or physical examination suggests a bleeding disorder beyond simple medication effect:
- Complete blood count with platelet count to evaluate for thrombocytopenia 2, 5
- PT (prothrombin time) and aPTT (activated partial thromboplastin time) detect most factor deficiencies 2, 5
- Peripheral blood smear to assess platelet morphology 2
Critical Pitfall to Avoid
Normal PT/aPTT does NOT rule out bleeding disorders - these tests miss von Willebrand disease, Factor XIII deficiency, and platelet function disorders 3, 2
When Initial Tests Are Normal But Suspicion Remains High
- Von Willebrand factor testing: VWF antigen, VWF activity (ristocetin cofactor), and Factor VIII levels 3, 2
- Platelet function testing: PFA-100 or platelet aggregation studies 1, 2
- Fibrinogen level to detect fibrinogen defects 2
Important Testing Caveat
Von Willebrand factor is an acute phase reactant and can be falsely elevated during stress or illness, requiring repeated testing for reliable results 3
When to Refer to Hematology
Immediate hematology consultation is warranted when:
- Specialized testing (VWF multimer analysis, Factor XIII assay, platelet function studies) is needed 2
- Initial screening reveals abnormalities requiring expert interpretation 2
- Strong clinical suspicion persists despite normal initial testing 5
- Patient requires preoperative clearance with history of easy bruising 2
Management Approach
If Medication-Related
- Assess risk-benefit of continuing anticoagulation/antiplatelet therapy versus bleeding risk 1
- Consider dose adjustment or alternative agents in consultation with prescribing specialist 1
If Bleeding Disorder Identified
- Treatment depends on specific diagnosis (desmopressin for von Willebrand disease, factor replacement for hemophilia, etc.) 2
- Avoid medications that further impair hemostasis 1, 2