Order of Draw for Blood Collection

Order of Draw for Blood Collection

Understanding the order of draw for blood collection is crucial for obtaining accurate laboratory results. The sequence in which blood tubes are filled minimizes the risk of contamination and ensures the integrity of the samples.

Blood Cultures

Blood cultures are critical for detecting infections.

  • First in the Draw: Blood culture bottles are always drawn first to avoid contamination from other tubes.

Sodium Citrate Tubes

  • Test Types: Prothrombin Time (PT), Partial Thromboplastin Time (PTT), International Normalized Ratio (INR).
  • Use: These tests are related to coagulation and require sodium citrate for accurate measurement.

Clot Activator Tubes

  • Type: The second tube is a clot activator, which promotes clotting of the blood sample.
  • Tests: This tube is used for serum tests, including drug levels. Sample must be allowed to clot for at least 30 minutes before centrifugation.
  • Common Tests: Comprehensive Metabolic Panel (CMP), Basic Metabolic Panel (BMP), Chemistry panels, lipid panels, and cholesterol tests.
  • Additive: Silica is commonly added to promote clotting.

Heparin Tubes

  • Purpose: Heparin tubes are often used for STAT (immediate) testing.
  • Tests: Common tests include Chemistry panels, troponin levels, electrolyte evaluation, and ammonia testing.

EDTA Tubes

  • Uses:
      - For Hematology: Complete Blood Count (CBC), Hemoglobin (HgB), Hematocrit (HCT), and Erythrocyte Sedimentation Rate (ESR).
      - For Blood Bank: Type and screen, crossmatch testing.
  • Function: EDTA (ethylenediaminetetraacetic acid) prevents clotting by binding calcium, thus facilitating hematological studies.

Post-Action and Other Additives

  • Oxalate + Coagulation Factors: Used for glucose, butanol, and lactic acid tests. Such tests must be processed quickly to avoid degradation.

Tests That Go on Ice

Certain specimens require refrigeration to ensure the stability of the analytes:

  • Tests Include: Lactic acid, ammonia, arterial blood gas (ABG), and pyruvate. These tests are sensitive to temperature and need to be handled with care.

Tests Protected from Light

  • Bilirubin: This test requires protection from light as exposure can alter the results significantly.

Tests Kept Warm

  • Cold Agglutination Tests: These tests require a warm environment and are typically performed on red serum due to the need for temperature maintenance to ensure accurate results.