Laboratory Evaluation for Easy Bruising
Initial Screening Panel
- The NHLBI recommends that patients presenting with bleeding symptoms (including easy bruising) receive a first‑line laboratory panel consisting of a complete blood count with platelet count, prothrombin time, activated partial thromboplastin time, and fibrinogen level (performed by ~90 % of clinicians) [1][3]5.
Von Willebrand Disease (VWD) Testing
- VWD affects up to 1 % of the population and is not reliably identified by PT/aPTT screening alone; therefore, VWF antigen, VWF activity (ristocetin cofactor or glycoprotein‑binding assay), and Factor VIII level should be added to the initial panel [1][3]4.
Interpretation When PT and aPTT Are Normal
- In the setting of normal PT and aPTT, easy bruising should raise suspicion for platelet dysfunction or VWD [2][4].
Limitations of Standard Screening Tests
- PT and aPTT may be completely normal in patients with clinically significant bleeding disorders, including mild hemophilia (Factor VIII or IX activity ≈ 25‑40 %) and most cases of VWD [2][4]6.
- Factor XIII deficiency can cause severe bleeding despite normal PT and aPTT [2][4].
Pediatric Considerations
- The American Academy of Pediatrics advises that children with easy bruising undergo CBC with platelet count (to screen for immune thrombocytopenia), PT and aPTT (to detect factor deficiencies), VWF testing (essential because VWD is not detected by PT/aPTT), and evaluation for vitamin K deficiency in infants lacking documented prophylaxis [2][7].
When to Refer to Hematology
- Referral is indicated when the initial screening reveals abnormal results requiring specialized interpretation [1][8].
- Referral is also warranted if strong clinical suspicion persists despite normal initial tests [1][8].
- Patients needing platelet function testing (e.g., light‑transmission aggregometry) or advanced investigations (e.g., Factor XIII, fibrinolytic defects, genetic testing) should be referred to a hematology specialist [2][5]7.