What is the appropriate protocol for ordering bleeding and platelet (B & P) blood testing for a patient?

Ordering Bleeding and Platelet (B & P) Blood Testing

Order a complete blood count (CBC), prothrombin time (PT), and activated partial thromboplastin time (APTT) as your initial hemostasis panel for any patient with suspected bleeding disorder. 1

Initial First-Line Testing Panel

When evaluating a patient for bleeding concerns, the following tests should be ordered together as a comprehensive first-line panel:

Essential Core Tests (Order for ALL patients)

• Complete Blood Count (CBC) - to assess platelet count and identify thrombocytopenia or thrombocytosis 1, 2
• Prothrombin Time (PT) - performed by 100% of specialists as first-line testing 2
• Activated Partial Thromboplastin Time (APTT) - performed by 100% of specialists as first-line testing 2
• Fibrinogen levels (Clauss and/or derived) - performed by 90% of specialists in first-line testing 2

Von Willebrand Disease Screening (Add if mucocutaneous bleeding history is strong)

• VWF antigen (VWF:Ag) 1, 2
• VWF ristocetin cofactor activity (VWF:RCo) 1, 2
• Factor VIII coagulant activity (FVIII) 1, 2

These three VWF tests are performed by 84% of specialists as first-line testing and should be ordered together, as all three are needed to establish diagnosis and suggest VWD type and severity. 1, 2

Additional First-Line Tests to Consider

• Factor VIII, IX, and XI assays - performed by 62% of specialists as first-line testing 2
• Iron studies/ferritin - performed by 69% of specialists, as iron deficiency is commonly overlooked despite being frequent in bleeding disorders 2
• ABO blood group - performed by 70% of specialists as first-line testing 2

Clinical Assessment Before Ordering Tests

Before ordering laboratory tests, document the following to guide your testing strategy:

• Bleeding Assessment Tool (BAT) score - used by 80% of specialists, with ISTH BAT being most common (73%) 2
• Family history - assessed by 98% of specialists 2
• Medication history - recorded by 88% of specialists, specifically documenting over-the-counter medications and NSAID use 2
• Physical examination findings - look for ecchymoses, hematomas, petechiae, evidence of liver disease (jaundice), splenomegaly, joint/skin laxity (Ehlers-Danlos), telangiectasia, signs of anemia, or anatomic lesions 1

When to Order Second-Line Testing

If initial tests are normal but clinical suspicion remains high based on bleeding history, order second-line tests including:

• Individual coagulation factors (FII, FV, FVII, FX, FXIII) - performed by 52-60% of specialists 2
• Platelet function testing (light transmission aggregometry) - performed by 60% of specialists 2, 3
• VWF multimer analysis - only if initial VWF testing shows abnormally low VWF:RCo or ratio of VWF:RCo to VWF:Ag below 0.5-0.7 1

Critical Pitfalls to Avoid

• Do NOT order bleeding time - it has insufficient specificity and sensitivity and is explicitly excluded from recommended diagnostic algorithms 3
• Do NOT order VWF multimer analysis as initial screening - it is technically complex, qualitatively interpreted, and should only be performed if initial VWF testing identifies abnormal results 1
• Do NOT use bleeding assessment tools as the sole determinant - they should guide but not exclusively determine testing strategy 2
• Do NOT ignore iron studies - iron deficiency is frequently overlooked despite being common in bleeding disorders 2

Special Circumstances

For Trauma Patients with Active Bleeding

• Maintain platelet count above 50×10⁹/L in patients with ongoing bleeding and/or traumatic brain injury 1
• Monitor coagulation parameters early and use to guide haemostatic therapy 1

For Sepsis/Septic Shock Patients

• Prophylactic platelet transfusion when counts are <10,000/mm³ in absence of bleeding 1
• Prophylactic platelet transfusion when counts are <20,000/mm³ if significant bleeding risk 1
• Higher platelet counts (≥50,000/mm³) advised for active bleeding, surgery, or invasive procedures 1