What is the recommended workup for a coagulation disorder?

Recommended Coagulation Workup

The initial coagulation workup should include prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen level, and platelet count, performed early and repeated as needed, with the addition of viscoelastic testing (thromboelastometry/thromboelastography) when available to provide real-time assessment of coagulation function. 1

Standard First-Line Laboratory Tests

The core panel must include:

• PT/INR: Evaluates the extrinsic and common coagulation pathways (factors II, V, VII, X, and fibrinogen), though it monitors only the initiation phase representing approximately 4% of thrombin production 2, 1
• APTT: Assesses the intrinsic and common pathways, detecting deficiencies in factors VIII, IX, XI, XII, and von Willebrand factor 2, 1
• Fibrinogen level (Clauss method): Critical as hypofibrinogenemia (<1.0 g/L) is often the first coagulation abnormality to develop and occurs after approximately 150% blood loss 1, 3
• Platelet count: Essential baseline measurement with critical thresholds of 50 × 10⁹/L in acute bleeding and 100 × 10⁹/L for traumatic brain injury 1
• Complete blood count with peripheral blood smear: Evaluates for anemia, thrombocytopenia, and platelet morphology 2, 3, 4

Enhanced Testing with Viscoelastic Methods

Viscoelastic testing (thromboelastometry/thromboelastography) should be performed alongside standard tests to characterize coagulopathy in real-time, as it provides results 30-60 minutes faster than conventional testing and can detect coagulopathy that may be missed when PT/APTT appear normal. 1

This testing is particularly valuable because:

• It assesses global hemostasis beyond the initiation phase 1
• It predicts the need for massive transfusion and mortality better than conventional tests 1
• It can identify hyperfibrinolysis, guiding tranexamic acid use 1

Context-Specific Expanded Testing

For Unexplained Bleeding Tendency

When bleeding history or clinical presentation suggests a bleeding disorder, expand testing to include:

• Von Willebrand factor studies: VWF antigen (VWF:Ag), VWF ristocetin cofactor activity (VWF:RCo), and factor VIII coagulant activity 3, 4
• Specific factor assays: Factor VIII, IX, and XI levels 3
• Factor XIII activity: Often overlooked in routine panels but important 3
• Rare coagulation factor assays: FII, FV, FVII, FX if family history pattern suggests inherited disorder 3
• Iron studies/ferritin: To assess for iron deficiency from chronic bleeding 3

For Suspected Platelet Disorders

When PT and APTT are normal but bleeding persists:

• Platelet function testing: Light transmission aggregometry with multiple agonists (ADP, collagen, epinephrine, ristocetin, arachidonic acid) 3
• Platelet flow cytometry: Evaluates platelet surface glycoproteins and activation markers 3
• VWF multimer analysis: Detects subtle abnormalities in VWF structure not apparent in routine testing 3

For Acute Trauma or Active Bleeding

In major trauma with hemorrhagic shock, the workup must be:

• Immediate and combined with metabolic markers (base deficit, lactate) 2, 1
• Point-of-care capable for rapid decision-making 1
• Repeated frequently as coagulopathy evolves rapidly during active bleeding or resuscitation 1

For Specific Clinical Scenarios

In intracerebral hemorrhage patients, routine admission testing should include complete blood count, PT/INR/APTT, creatinine/estimated glomerular filtration rate, glucose, cardiac troponin and ECG, toxicology screen, and inflammatory markers (ESR and/or CRP) to identify hemorrhage type, active medical issues, and risk of unfavorable outcomes. 2

In cirrhosis patients undergoing procedures, standard coagulation tests (PT/INR, platelet count) do not reliably predict bleeding risk, and routine prophylactic blood product transfusion is not recommended for common gastrointestinal procedures. 2

Critical Interpretation Pitfalls to Avoid

• Do not rely on single measurements: PT/APTT can appear normal while overall coagulation is severely abnormal, particularly in early traumatic coagulopathy 2, 1
• Do not delay testing: Fibrinogen drops first and fastest; waiting for clinical coagulopathy before testing leads to delayed intervention and worse outcomes 1
• Beware of false prolongation: APTT can be falsely prolonged with lupus anticoagulant or in factor XII deficiency (which does not cause bleeding) 2
• Consider specimen handling: Coagulation tests are very sensitive to specimen handling; inappropriate handling commonly leads to false-positive results 2
• Account for transient coagulopathy: Patients with traumatic brain injury often have transient coagulopathy from parenchymal damage that does not reflect an underlying congenital disorder 2

When to Consult Hematology

Refer to hematology when:

• Abnormal coagulation studies are identified 4
• Low VWF levels are detected 4
• Strong bleeding history persists despite normal initial tests 4
• Specific expanded testing for rare disorders is needed 2
• Preliminary testing suggests presence of a bleeding disorder 2
• Severe thrombocytopenia (platelet count <25 × 10⁹/L) is present 2

Special Considerations for Von Willebrand Disease Testing

Be aware that VWF levels can be falsely elevated by: acute stress, anxiety, recent exercise, acute or chronic inflammatory illness, pregnancy or estrogen/oral contraceptive use, and blood group O individuals having 25% lower baseline VWF levels. 4

Ensure atraumatic blood draw at room temperature when ordering VWD studies, and testing may need to be repeated up to 3 times to ensure reliable results. 2, 4

Predictive Value of History

A positive family history of bleeding and positive personal history of bleeding are the strongest predictors of an underlying coagulopathy. 5 In the absence of personal or family history of bleeding, normal PT and/or APTT on repeat testing has a negative predictive value of more than 95%. 5

However, normal coagulation studies and von Willebrand parameters do not rule out all bleeding disorders, as some disorders have variable expression. 3