Laboratory Evaluation for Skin Bruises in an Elderly Female
Order a complete blood count with platelet count and peripheral smear, PT/INR, aPTT, and consider von Willebrand disease testing if initial screening is normal but clinical suspicion remains high. 1
First-Line Essential Laboratory Tests
The initial workup should include the following core tests to evaluate for the most common and clinically significant bleeding disorders:
- Complete Blood Count (CBC) with platelet count and peripheral blood smear to assess for thrombocytopenia, abnormal platelet morphology, or hematologic malignancies 1
- Prothrombin Time (PT/INR) to evaluate the extrinsic coagulation pathway and detect vitamin K deficiency, liver disease, or factor VII deficiency 1
- Activated Partial Thromboplastin Time (aPTT) to assess the intrinsic coagulation pathway and screen for hemophilia and other factor deficiencies 1
- Fibrinogen level to detect fibrinogen disorders that may not be apparent on routine coagulation testing 1
Critical Pitfall to Avoid
Do not assume normal PT/aPTT rules out all bleeding disorders. These screening tests will miss von Willebrand disease (the most common inherited bleeding disorder), Factor XIII deficiency, and platelet function disorders—all of which can cause significant bruising in elderly patients 1, 2. This is a common error that leads to missed diagnoses.
Additional Testing When Initial Screening is Normal
If the patient has concerning bruising patterns but initial tests are normal, proceed with:
- Von Willebrand factor antigen (VWF:Ag), von Willebrand factor ristocetin cofactor activity (VWF:RCo), and Factor VIII coagulant activity to establish or exclude von Willebrand disease 1
- Liver function tests to assess hepatic synthetic function, as liver disease commonly causes coagulopathy in elderly patients 3
- Renal function (urea and electrolytes) as uremia can affect platelet function 3
Age-Specific Considerations for Elderly Females
In elderly patients, consider additional testing based on clinical context:
- Ferritin and inflammatory markers (ESR or CRP) if there is concern for underlying systemic disease or malignancy 3
- Vitamin D and calcium/phosphate if there are concerns about bone health or metabolic bone disease contributing to trauma susceptibility 1
- Medication review is essential, as elderly patients frequently take anticoagulants, antiplatelets, NSAIDs, or corticosteroids that increase bruising tendency 2
Clinical Context Matters
The pattern and location of bruising should guide the extent of workup:
- Senile purpura (bruising on sun-exposed areas like forearms) is common in elderly patients due to vascular fragility and may not require extensive testing if the pattern is typical 2
- Unexplained or extensive bruising warrants full evaluation including von Willebrand testing even if PT/aPTT are normal 1, 2
- Mucocutaneous bleeding (nosebleeds, gum bleeding, heavy menstrual bleeding if applicable) alongside bruising strongly suggests von Willebrand disease and mandates specific VWF testing 1, 2
When to Refer for Specialized Testing
If screening tests are abnormal or there is a strong clinical suspicion despite normal initial tests, refer to hematology for:
- Platelet function testing (platelet aggregation studies) if platelet count is normal but clinical suspicion for platelet dysfunction is high 2, 4
- Factor XIII assay if other tests are normal but severe bruising persists, as this deficiency is not detected by standard coagulation tests 2
- Specialized von Willebrand disease assays including VWF multimer analysis if initial VWD testing shows abnormal results or low VWF:RCo to VWF:Ag ratio (below 0.5-0.7) 1