What labs are included in a trauma workup?

Laboratory Tests in Trauma Workup

A comprehensive trauma workup should include complete blood count, coagulation studies, serum lactate or base deficit, liver and pancreatic enzymes, renal function tests, and urinalysis as the core laboratory tests to assess bleeding, organ damage, and metabolic status. 1

Core Laboratory Tests for Trauma Patients

Hematologic Assessment

• Complete Blood Count (CBC) including:
  • Hemoglobin/Hematocrit (Hb/Hct)
    • Single measurements may mask early bleeding
    • Serial measurements increase sensitivity for detecting ongoing blood loss 1
  • White blood cell count
  • Platelet count

Coagulation Studies

• Basic coagulation panel:

  • Prothrombin Time (PT)/International Normalized Ratio (INR)
  • Activated Partial Thromboplastin Time (aPTT)
  • Fibrinogen
  • D-dimer (if available)

• PT/INR is more sensitive than aPTT (84% vs 50%) for detecting coagulation factor deficiencies in trauma patients 2

Metabolic Assessment

• Serum lactate and/or base deficit measurements
  • Sensitive indicators of tissue hypoperfusion and shock severity
  • Provide early objective evaluation of patient's response to resuscitation 1
  • Strong recommendation (Grade 1B) for use in monitoring extent of bleeding and shock 1

Organ Function Tests

• Liver function tests:

  • AST/ALT (transaminases)
  • Particularly important with suspected abdominal trauma
  • Levels >400 U/L correlate with liver injury 3

• Pancreatic enzymes:

  • Amylase/lipase for suspected pancreatic injury

• Renal function tests:

  • Blood urea nitrogen (BUN)
  • Creatinine
  • Urinalysis (to detect hematuria)

Additional Tests Based on Clinical Context

• Cardiac markers:

  • Troponin and/or creatine kinase for suspected cardiac injury 1

• Toxicology screen:

  • Alcohol levels
  • Drug screen when indicated

Specialized Testing in Specific Scenarios

For Patients on Anticoagulants

• Standard coagulation tests plus specific tests based on medication:
  • Anti-Xa levels for patients on DOACs or heparin
  • Thrombin time for dabigatran 1

For Suspected Coagulopathy

• Consider viscoelastic hemostatic assays:
  • Thromboelastography (TEG)
  • Rotational Thromboelastometry (ROTEM)
  • More accurate than conventional coagulation tests for detecting trauma-induced coagulopathy 4

Common Pitfalls and Caveats

1. Relying on single Hct/Hb measurements:

   • Initial values may be normal despite significant bleeding
   • Serial measurements are more reliable 1

2. Delayed recognition of coagulopathy:

   • Early, repeated, and combined measurements of coagulation parameters are essential 1

3. Overreliance on laboratory tests:

   • Laboratory values should be interpreted in conjunction with clinical assessment
   • Some studies suggest routine laboratory panels have limited value in pediatric trauma 3

4. Inadequate coagulation factor replacement:

   • Coagulopathy is common during major trauma resuscitation
   • Timely administration of blood products is crucial 5

Prioritization of Tests

For the critically injured trauma patient, prioritize:

1. CBC with platelets
2. Coagulation studies (PT/INR, aPTT)
3. Serum lactate and/or arterial blood gas with base deficit
4. Basic metabolic panel
5. Liver enzymes and urinalysis

Remember that laboratory testing should be performed in parallel with clinical assessment and appropriate imaging studies. The European guidelines emphasize that near-patient testing results should be readily available under ideal circumstances 1.