What is the initial step in a bleeding workup (evaluation of bleeding disorders)?

Initial Workup for Bleeding Disorders

The initial step in a bleeding workup should include a thorough clinical evaluation with a bleeding assessment tool (BAT) followed by first-line laboratory tests consisting of activated partial thromboplastin time (aPTT), prothrombin time (PT), complete blood count with platelet count, and von Willebrand factor (VWF) assays. 1, 2

Clinical Evaluation

• Bleeding Assessment Tool (BAT): 80% of hemostasis specialists use a standardized BAT, with the ISTH BAT being the most common (73%) 1
• Key clinical information to collect:
  • Family history of bleeding (98% of specialists assess this) 1
  • Medication use, especially over-the-counter drugs and NSAIDs (88% of specialists record this) 1
  • Assessment for hypermobility (55% of specialists routinely check) 1

First-Line Laboratory Testing

According to the International Society on Thrombosis and Haemostasis (ISTH) survey, the following tests are performed as first-line investigations by hemostasis specialists 1:

1. Coagulation screening tests (100% of specialists):

   • Activated Partial Thromboplastin Time (aPTT)
   • Prothrombin Time (PT)

2. Complete Blood Count:

   • Full blood count (65% of specialists)
   • Platelet count

3. Von Willebrand Disease testing (84% of specialists):

   • VWF antigen (VWF:Ag)
   • VWF ristocetin cofactor activity (VWF:RCo)
   • Factor VIII coagulant activity (FVIII:C)
   • VWF:RCo/VWF:Ag ratio 2

4. Additional first-line tests:

   • Fibrinogen levels (90% of specialists) 1
   • Factor VIII, IX, and XI assays (62% of specialists) 1
   • ABO blood group (70% of specialists) 1
   • Iron studies (69% of specialists) 1

Interpretation of Initial Results

• Abnormal aPTT alone: Suggests deficiency in intrinsic pathway factors (VIII, IX, XI) or presence of inhibitors 3, 4
• Abnormal PT alone: Indicates deficiency in vitamin K-dependent factors (II, VII, IX, X) or factor V 4
• Low platelet count alone: Consider peripheral destruction, immunothrombocytopenia, or bone marrow production issues 4
• VWF abnormalities: May indicate von Willebrand Disease, which requires further characterization into subtypes 2

Common Pitfalls to Avoid

1. Overreliance on screening tests: PT and aPTT have extremely low sensitivity (1.0%-2.1%) for detecting clinically significant bleeding disorders 5

2. Failure to use BAT scores appropriately: An abnormal BAT score should influence both first-line (13%) and second-line testing (37%) or both (53%) 1

3. Ignoring medication effects: Many medications, especially NSAIDs, can affect platelet function and bleeding risk 3

4. Not accounting for physiological variations: VWF levels can be influenced by blood type, pregnancy, stress, and thyroid function 3

5. Premature cessation of workup: If initial tests are normal but clinical suspicion remains high, consider bleeding disorder of unknown cause (BDUC) requiring specialized testing 6

If first-line tests are normal but bleeding symptoms persist, second-line testing should include platelet function testing (60% of specialists), additional factor assays including FXIII (60%), and potentially genetic testing (48%) 1.

By following this structured approach to the initial bleeding workup, clinicians can efficiently identify the most common bleeding disorders while establishing a foundation for more specialized testing if needed.