What labs should be ordered prior to blood transfusion?

Laboratory Testing Prior to Blood Transfusion

All patients require a full blood count, blood group with full red cell antibody screen, and basic metabolic panel (urea and electrolytes) before any blood transfusion. 1

Essential Pre-Transfusion Laboratory Tests

Core Required Tests

• Complete Blood Count (CBC) with hemoglobin concentration is mandatory to establish baseline values and assess the need for transfusion 1
• Blood group (ABO/Rh) typing and full red cell antibody screen must be performed on all patients to prevent ABO incompatibility reactions, which remain a leading cause of transfusion-related mortality 1
• Renal function tests (urea and electrolytes/creatinine) are required to identify patients at risk for transfusion-associated circulatory overload (TACO), particularly those with renal failure 1

Critical Timing Requirements

• If the patient has been transfused within the previous 3 months, a repeat full blood count and antibody screen must be obtained within 72 hours before the planned transfusion 1
• Two separate blood samples are typically required unless a suitable "historical" sample with adequate patient identification is available on file 1
• Blood samples must be collected and labeled at the patient's bedside by trained personnel, with four core identifiers: surname, forename, date of birth, and unique hospital identification number 1

Additional Testing Based on Clinical Context

For Patients with Active Bleeding or Coagulopathy

• Point-of-care viscoelastic testing (TEG, ROTEM, Quantra, or ClotPro) should be used to rapidly assess coagulation status and guide hemostatic resuscitation in major hemorrhage 1
• Coagulation profile (PT, aPTT, INR) is essential for identifying bleeding risk, particularly in patients on anticoagulants 2
• Fibrinogen levels should be measured as hypofibrinogenemia commonly occurs with massive hemorrhage 3

For High-Risk Patient Populations

• Brain natriuretic peptide (BNP) should be considered in patients at high risk for TACO (age >70 years, heart failure, renal failure, hypoalbuminemia, low body weight) 1
• Baseline oxygen saturation measurement is required for patients with sickle cell disease 1
• Transcranial Doppler results (within 12 months) should be documented for children <16 years with sickle cell disease 1

Special Considerations for Sickle Cell Disease

• Blood samples must be clearly labeled indicating sickle cell disease diagnosis 1
• The transfusion laboratory must be contacted directly with patient details including NHS number and transfusion history to allow time for phenotype-matched blood procurement 1
• Patients should carry a transfusion card documenting their red cell phenotype/genotype and known alloantibodies 1

Common Pitfalls to Avoid

• Never proceed with transfusion if there are any discrepancies between the compatibility label and patient identification—contact the transfusion laboratory immediately 1
• Do not assume hemoglobin concentration accurately reflects blood loss in actively bleeding patients, as it may remain falsely elevated due to inadequate fluid resuscitation 1, 4
• Avoid wrong-blood-in-tube events by ensuring positive patient identification with a wristband containing all four core identifiers before sample collection 1
• Do not delay obtaining group and antibody screen in patients with known alloantibodies or complex transfusion requirements, as suitable blood may take significant time to procure 1

Post-Transfusion Monitoring

• Hemoglobin should be measured before and after every unit of red blood cells transfused in stable, normovolemic patients 1, 4
• Post-transfusion hemogram should be obtained 10-60 minutes after completion to verify adequate response 4
• Vital signs (heart rate, blood pressure, temperature, respiratory rate) must be documented pre-transfusion, at 15 minutes, and within 60 minutes post-transfusion 1