What lab work is recommended for a 40-year-old female presenting with easy bruising?

Laboratory Workup for Easy Bruising in a 40-Year-Old Female

The initial laboratory evaluation should include a complete blood count (CBC) with platelet count, peripheral blood smear, prothrombin time (PT), activated partial thromboplastin time (aPTT), and fibrinogen level if PT or aPTT are abnormal. 1, 2

Essential Clinical History Before Testing

Before ordering labs, obtain specific bleeding history to determine if testing is even warranted:

• Ask about significant bleeding after surgery, dental procedures, or menorrhagia – these symptoms suggest an underlying bleeding disorder that warrants laboratory investigation 1
• Document all medications including NSAIDs, anticoagulants, antiplatelets, steroids, and alternative/herbal therapies, as these commonly cause bruising and affect test results 1, 2
• Obtain family history of bleeding disorders, as hereditary conditions like von Willebrand disease may be present 1, 3
• Assess for systemic illness such as liver disease, renal disease, or connective tissue disorders (Ehlers-Danlos syndrome) that can cause easy bruising 1

Initial Laboratory Panel

The screening tests should include:

• CBC with platelet count and peripheral blood smear – identifies thrombocytopenia, platelet abnormalities, and hematologic malignancies 1, 2
• PT and aPTT – screens for most coagulation factor deficiencies 1, 2
• Fibrinogen level – add this if PT or aPTT are abnormal to detect fibrinogen defects 1

Critical Limitation to Recognize

PT and aPTT do NOT reliably detect von Willebrand disease (VWD) or factor XIII deficiency, which are among the most common inherited bleeding disorders 1. If clinical suspicion remains high despite normal screening tests, referral to hematology is warranted for specialized testing including von Willebrand factor activity and antigen levels 1, 2.

Interpretation Algorithm

• Normal PT and aPTT → suggests platelet disorder (most commonly VWD); consider platelet function testing and hematology referral 2, 3
• Normal PT, prolonged aPTT → indicates intrinsic pathway defect; perform mixing study to differentiate factor deficiency from inhibitor 3
• Prolonged PT, normal aPTT → suggests extrinsic pathway disorder; consider vitamin K deficiency or early liver disease 3
• Both PT and aPTT prolonged → evaluate for liver failure, disseminated intravascular coagulation (DIC), or combined factor deficiencies 3

When NOT to Test Extensively

Do not perform extensive testing without clinical indication, as most bleeding disorders are extremely rare and universal screening is unreasonable 1. If the patient has no personal or family history of abnormal bleeding with trauma or surgery, and bruising is mild without other bleeding symptoms, reassurance may be appropriate after basic screening 4, 5.

Referral Indications

Refer to hematology when:

• Initial laboratory evaluation indicates a bleeding disorder 1, 2
• High clinical suspicion persists despite normal laboratory workup 1, 2
• Specialized testing (platelet function analyzer, von Willebrand studies, factor assays) is needed 1