What are the current guidelines for perioperative blood requisition, including pre‑operative anemia screening, blood ordering calculations, and transfusion thresholds?

Latest Guidelines for Perioperative Blood Requisition

Use a maximal surgical blood order schedule (MSBOS) to guide preoperative blood ordering, measure hemoglobin before all major elective surgery, and implement restrictive transfusion thresholds of 7-8 g/dL for most hemodynamically stable patients. 1, 2

Pre-operative Anemia Screening and Preparation

All patients must have hemoglobin measured before listing for major elective surgery 1. When anemia is detected, the following actions should be taken:

Iron Deficiency Management

• Administer iron to patients with iron deficiency anemia if time permits before surgery 2
• For surgeries with moderate to high bleeding risk or known preoperative anemia, detect and correct iron deficiency well in advance 3
• Intravenous iron is preferred for rapid correction 3, 4

Erythropoietin Considerations

• May be administered when possible to reduce allogeneic blood needs in selected populations (renal insufficiency, anemia of chronic disease, refusal of transfusion) 2
• Caution: Requires weeks to induce significant hemoglobin increase and is expensive 2

Patient Consent

• Discuss transfusion and alternatives with patients before surgery when blood transfusion is anticipated, documenting consent per local protocols 1
• Inform patients of potential risks versus benefits 2

Blood Ordering Calculations

Implement an institution-specific MSBOS as the primary strategy to improve efficiency of blood ordering practices 2, 5. This approach:

• Reduces unnecessary preoperative blood orders by up to 38% 5
• Decreases crossmatch-to-transfusion ratios by 27% 5
• Saves approximately $6-7 per patient 5
• Results in only clinically insignificant increases in emergency release blood requirements 5

Blood Availability

• Ensure blood and blood components are available for patients when significant blood loss or transfusion is expected 2
• Review available laboratory results including hemoglobin, hematocrit, and coagulation profiles 2

Transfusion Thresholds

Restrictive Strategy (Preferred)

A restrictive red blood cell transfusion strategy may be safely used to reduce transfusion administration 2. The 2023 AABB International Guidelines provide the most current, evidence-based thresholds 6:

For Hospitalized Adults (Hemodynamically Stable):

• Standard threshold: Consider transfusion when hemoglobin <7 g/dL (strong recommendation, moderate certainty evidence) 6
• Cardiac surgery: May use threshold of 7.5 g/dL 6
• Orthopedic surgery or preexisting cardiovascular disease: May use threshold of 8 g/dL 6
• Hematologic/oncologic disorders: Consider transfusion when hemoglobin <7 g/dL (conditional recommendation, low certainty evidence) 6

For Pediatric Patients:

• Critically ill children (hemodynamically stable, without hemoglobinopathy): Transfuse when hemoglobin <7 g/dL (strong recommendation, moderate certainty evidence) 6
• Congenital heart disease: Use disease-specific thresholds:
  • Biventricular repair: 7 g/dL
  • Single-ventricle palliation: 9 g/dL
  • Uncorrected congenital heart disease: 7-9 g/dL 6

Clinical Decision-Making for Hemoglobin 6-10 g/dL

The determination of whether hemoglobin concentrations between 6 and 10 g/dL justify transfusion should be based on 2:

• Potential or actual ongoing bleeding (rate and magnitude)
• Intravascular volume status
• Signs of organ ischemia
• Adequacy of cardiopulmonary reserve

Administer red blood cells unit-by-unit when possible, with interval reevaluation 2

Intraoperative Blood Management Strategies

Antifibrinolytics

Use tranexamic acid for prophylaxis in 2, 1:

• All patients undergoing cardiopulmonary bypass
• Patients with blood loss >500 mL (>8 mL/kg in children >10 kg) anticipated
• Certain orthopedic surgeries
• Liver surgery and high-risk bleeding situations
• Patients unable to receive donor blood

Cell Salvage

• Recommended for patients at high risk of excessive bleeding or transfusion 1
• Consider acute normovolemic hemodilution (ANH) for high-risk bleeding cases (major cardiac, orthopedic, thoracic, or liver surgery) 2
• Reinfuse recovered red blood cells intraoperatively when appropriate 2

Anticoagulant Management

Balance bleeding risk versus thrombosis risk when altering anticoagulation 2, 1:

• Discontinue warfarin, anti-Xa drugs, antithrombin agents for elective surgery in consultation with specialist 2
• Transition to shorter-acting drugs (heparin, LMWH) may be appropriate 2
• Critical caveat: Do NOT stop clopidogrel and aspirin in patients with coronary stents placed within 3 months (bare metal) or 1 year (drug-eluting) due to MI risk 2
• Discontinue non-aspirin antiplatelet agents (clopidogrel, ticagrelor, prasugrel) sufficiently in advance, except for recent PCI patients 2

Major Hemorrhage Protocols

Every institution should have a major hemorrhage protocol that is regularly audited and reviewed 1. These protocols should:

• Be concise but targeted to different clinical contexts 1
• Allow immediate release and protocolized administration of blood components 2, 1
• Optimize delivery of blood products to massively bleeding patients 2

Obstetric Bleeding

Early recognition is essential—measure blood loss accumulatively with clear escalation plans and multidisciplinary team involvement 1

Postoperative Management

Monitoring

• Limit blood sampling to minimize iatrogenic anemia 1, 3
• Monitor postoperative anemia and implement corrective measures (particularly intravenous iron) 3

Blood Component Storage

• Administer blood without consideration of duration of storage 2
• Leukocyte-reduced blood may be used to reduce complications 2

Key Implementation Points

The most recent 2025 Association of Anaesthetists guidelines 1 emphasize that all anaesthetists involved in care of patients at risk of major bleeding should be aware of available treatment options. The guidelines prioritize organizational factors for safe transfusion, context-specific protocols for major bleeding, and strategies to avoid transfusion need while minimizing bleeding.