Transfusion of whole blood or fractionated blood components is a widely used method for managing numerous conditions. Packed red blood cells (pRBCs), the most commonly transfused products, are primarily used for the treatment of acute and chronic blood loss. RBC transfusion elevates hemoglobin (Hb) levels and helps maintain organ perfusion and tissue oxygenation. The decision to transfuse RBCs is based on the patient's Hb level, hemodynamic status, and comorbidities (e.g., cardiovascular disease). Fresh frozen plasma (FFP), cryoprecipitate, platelet, and clotting factor transfusions are also available. Pretransfusion testing must be performed, unless in an emergency situation, to minimize the risk of transfusing incompatible RBCs and subsequent . Testing involves blood typing (ABO and Rhesus) of the recipient's blood, RBC antibody screening of the recipient's serum or plasma, and compatibility testing (crossmatching recipient serum or plasma and donor RBCs).
See also “Transfusion reactions.”
Blood type systems
There are more than 250 antigens on the RBC surface, which are classified into several antigen-antibody systems or blood groups. Blood type is most commonly communicated as a combination of ABO blood type and Rhesus blood type (e.g., O- for blood products and AB+ for blood products). 
ABO blood type system 
- Consists of 2 antigens (A antigen and B antigen) that can be present in isolation or in combination, or be absent
- Anti-A and/or anti–B antibodies
|ABO blood types |
|Type||Blood type O||Blood type A||Blood type B||Blood type AB|
|Prevalence||∼ 45%||∼ 40%||∼ 10%||∼ 5%|
|Antigens on RBCs||No antigens||A antigen||B antigen||A and B antigens|
|Antibodies in plasma||Anti-A and anti-B antibodies||Anti-B antibodies||Anti-A antibodies||No antibodies|
|Can receive RBCs from||O||A, O||B, O||AB, A, B, O (universal RBC recipients)|
|Can donate RBCs to||O, A, B, AB (universal RBC donors)||A, AB||B, AB||AB|
|Can receive FFP from||O, A, B, AB (universal FFP recipients)||A, AB||B, AB||AB|
|Can donate FFP to||O||A, O||B, O||AB, A, B, O (universal FFP donors)|
Rhesus blood type system 
- Consists of > 45 Rhesus (Rh) antigens of which Rh(D) antigen is the most immunogenic and clinically significant 
- In clinical practice, Rh status typically refers to the presence or absence of Rh(D) antigen, despite the existence of other Rh antigens (see “Extended RBC antigens”).
- Anti-Rh antibodies
|Rh blood types |
|Prevalence||1–15% ||85–99% |
|Rh(D) antigen on RBCs||Absent||Present|
|Antibodies in plasma||Anti-Rh antibodies can form after sensitization||No anti-Rh antibodies|
|Can receive RBCs from|| |
Rh negative (preferably)
|Rh positive, Rh negative|
|Can donate RBCs to||Rh negative, Rh positive||Rh positive|
In Rh-negative women of childbearing age, exposure to Rh-positive RBCs (e.g., by transfusion or ) can trigger , which can cause in subsequent pregnancies. Rh-negative donor blood is therefore preferred in these patients, however, Rh-positive blood is acceptable if an is required.
Extended RBC antigen systems 
Several other antigen groups can trigger antibody formation in antigen-negative individuals after exposure to antigen-positive RBCs. Only some cause clinically significant hemolytic anemias and/or transfusion reactions.
- antigens, e.g., Rh(C) and Rh(E), are less frequent and typically considered among the spectrum of extended RBC antigens.  : Most non-D Rh
- Kell antigen system
- Duffy antigen system 
- Kidd antigen system 
- MNS antigen system 
Transfusion safety measures
Blood bank measures
- Blood products for transfusion can be allogeneic (i.e., from a donor) or .
- Systemic measures are taken by blood banks and blood donation services prior to release for transfusion to reduce risks associated with individual donor units.
- Allogeneic donor blood is tested to determine blood type, screened for common infectious diseases, and then leukoreduced.
- Some blood donations undergo additional processing to further reduce the risk of complications in high-risk groups.
- Blood for autologous transfusion typically undergoes minimal processing intraoperatively prior to retransfusion. 
- All prospective blood donors in the United States undergo screening via a donor history questionnaire (DHQ), e.g., to identify infectious risk (see “antiplatelet agents) and/or noninfectious conditions (e.g., cancer).  ”) and high-risk medications (e.g.,
- Leukoreduction: filtration of leukocytes out of cellular blood products 
Blood donation infection screening
- DHQ screening may exclude donors for a variable or indefinite period if they meet specific criteria, e.g., certain behavioral endemic areas for specific pathogens, e.g., vCJD, malaria.  , history or active features of transmissible illnesses, and/or time spent in
- Laboratory screening: performed on all units received for blood donation
Blood products for patients with certain preexisting conditions may require further processing to reduce the risk of complications.
- Irradiation 
- Washing 
- Volume reduction 
Pretransfusion safety practices 
- Consider transfusion therapy when benefits outweigh the risks and have been excluded.
- Choose condition-specific transfusion thresholds and indications tailored to individual patient needs, for example:
- Whenever possible:
- Ensure that the right blood product is being transfused to the right patient at the right time.
- Do not delay life-saving transfusions.
- Only defer life-saving blood transfusions if a clear and valid prohibits their use or an individual with declines transfusion after an informed discussion.
Patients who do not wish to accept blood transfusions (e.g., Jehovah's witnesses) are advised to carry an advance directive card. However, in life-threatening situations, if the patient cannot be consulted and clear advance directives are not available, blood products should be given.
Ensure the following whenever possible:
- Check patient records to identify any special transfusion requirements.
- Discuss transfusion risks, benefits, and surrogate decision-makers. in detail with patients or
- Document informed consent.
- Order pretransfusion testing as indicated by transfusion product: e.g., type and screen, crossmatching.
- Transfuse blood products within normal working hours for all nonurgent transfusions. 
- Use fully crossmatched blood products as soon as they are available.
Requests and prescriptions
Ensure the following are appropriately labeled, documented, and communicated:
- Two independent patient identifiers (e.g., full name and unique medical record number)
- Reasons for transfusion
- Type and number of units of the blood product to be transfused
- Rate or duration of transfusion
- Special requirements (e.g., washed or irritated products)
- Name and contact details of the requesting clinician
Safety check prior to administration 
- Confirm the patient's identity.
- Check if the correct blood products have been issued.
- Ensure blood product containers are undamaged and contents appear normal.
Compare patient and blood product identifiers immediately prior to transfusion. Do not transfuse if there is any discrepancy!
Transfusion administration 
See “Fractionated blood components” for component-specific administration instructions.
- Give blood component transfusions through a standard blood infusion set.
- Use blood-warming devices in patients with or those requiring multiple transfusions.
Rate of administration
- When possible, transfuse at a slower rate for the first 15 minutes.
- Complete all transfusions within 4 hours of removing the blood product from temperature-controlled storage. 
- Check clinical status and vital signs for every unit transfused:
- Monitor for , especially in patients requiring multiple transfusions.
- Observe inpatients for 24 hours after transfusion.
Follow the vital signs or becomes acutely unwell during or in the hours following a transfusion. for any patient who has a change in
- Goal: Ensure compatibility between recipient and donor blood products and avoid hemolytic .
- Methods: A variety of test strategies that mostly rely on hemagglutination (i.e., clumping of erythrocytes) induced by antibodies binding to RBC antigens (see “Overview of pretransfusion testing” for more specific methods.)
- Standard testing requirements: vary by blood product and institutional policy
- up to 25 minutes alone:
- up to 75 minutes :
- crossmatch: up to 120 minutes and
- Routine testing: Order advance pretransfusion testing based on anticipated transfusion requirements. 
Extended RBC phenotype matching: matches donor units to the recipient based on their profile 
- Involves detailed serological and genetic profiling of crossmatching ( can be several days) to select compatible donor units followed by serologic
- Performed early in patients with anticipated long-term or recurrent transfusion needs (e.g., due to sickle cell disease, thalassemia) to prevent alloimmunization and transfusion reactions.
Transfuse blood products with complete pretransfusion testing whenever possible. If life-saving transfusion is required before pretransfusion testing is complete, use until fully tested blood products are available.
|Overview of pretransfusion testing |
|1. Type and screen ||Blood typing|| |
|RBC antibody screen|| || |
|2. Crossmatching ||Electronic crossmatch|| || |
|Serologic crossmatch|| || || |
Whole blood 
- Content: all blood components
Fractionated blood components
Fractionated blood components are prepared by separating whole blood into its constituent elements and storing each under ideal conditions.
- FFP) (
Recommendations in this section are consistent with the 2015 AABB guideline for red cell transfusion. 
- Must be ABO compatible
- Give Rh(D)-negative recipients Rh(D)-negative pRBCs if possible.
- See also “Type and screen” and “Crossmatching.”
The decision to transfuse should be made on a case-by-case basis. 
- Hemorrhagic shock or ongoing rapid blood loss
- Exchange transfusion: e.g., in severe sickle cell disease or methemoglobinemia
- Severe anemia (even if asymptomatic)
Moderate anemia, in any of the following situations:
- Increased risk of complications, e.g., acute onset , significant comorbidities, older age
- Planned surgery
Restrictive transfusion thresholds (i.e., Hb 7–8 g/dL) in hemodynamically stable patients are associated with similar clinical outcomes and less blood use and adverse effects compared to liberal thresholds (9–10 g/dL) 
- Dose 
- Usual rate: 90–120 minutes per unit 
- ↑ Hb and oxygen-carrying capacity of the blood
- 1 unit of pRBCs increases Hb value by ∼ 1 g/dL.
- Intravascular volume expansion roughly equivalent to unit volume
- Repeated transfusions can lead to .
- See also “Transfusion reactions.”
Recommendations in this section are consistent with the 2015 AABB guideline for platelet transfusion. 
- Platelets suspended in plasma or platelet additive solution 
- Typically provided as either of the following: 
Compatibility requirements 
- ABO compatibility: preferred but not required for routine transfusions 
- Rh(D) matching: Rh(D)-negative platelets are preferred in Rh(D)-negative recipients to prevent alloimmunization. 
- Consider donor plasma compatibility when transfusing multiple units. 
Indications for platelet transfusion 
- Treatment of active bleeding in patients with any of the following:
Prevention of bleeding in any of the following situations:
- Severe thrombocytopenia (platelets < 10,000/mm3 ) secondary to active treatment-induced 
- Patients with thrombocytopenia who are due to undergo invasive procedures ; 
- Childbirth, if maternal platelets are < 50,000/mm3
- Thrombocytopenia due to chronic bone marrow failure not associated with myelosuppressive therapy (e.g., chemotherapy, radiation) 
- Vaccine-induced immune thrombotic thrombocytopenia (VITT) 
- Transfuse 1 unit of apheresis platelets or 1 pack of pooled platelets to prevent bleeding due to severe thrombocytopenia (platelets < 10,000/mm3 ). 
- In massive hemorrhage, follow the ratio recommended in the .
- For other indications, use the minimum dose required to restore platelets to the recommended transfusion thresholds.
- Usual rate: 30–60 minutes per apheresis platelets unit/pooled platelets pack 
- 1 unit of apheresis platelets or 1 pack of pooled platelets increases the platelet count by 20–60,000/mm3. 
- Intravascular volume expansion roughly equivalent to unit/pack volume
- Multiple platelet transfusions may lead to platelet transfusion refractoriness. 
- See also “Transfusion reactions.”
FFP and cryoprecipitate
Fresh frozen plasma 
Recommendations in this section are consistent with the 2010 AABB guideline for plasma transfusion. 
Compatibility requirements: See “ABO blood type system.”
- ABO compatibility must be considered. 
- Rh(D) matching: not required 
- Management of coagulopathy in patients with multiple clotting factor deficiencies (e.g., due to liver cirrhosis, DIC)
- Prevention of dilutional coagulopathy in massive transfusion
- Plasma exchange transfusion, e.g., in TTP 
- Management of some coagulation factor deficiencies if no specific concentrate for treatment exists
- Alternative therapy for:
- Dose: 10–20 mL/kg 
- Usual rate: 10–20 mL/kg/hour 
- Complications: See “Transfusion reactions.”
- Content: clotting factors (fibrinogen, factor VIII, factor XIII), vWF, and fibronectin
- ABO compatibility: preferred but not required 
- Rh(D) matching: not required 
- Dose: typically 1 unit per 7–10 kg of the patient's body weight 
- Usual rate: 10–20 mL/kg/hour 
- Effect: 1 unit of cryoprecipitate per 7–10 kg of the patient's body weight increases serum fibrinogen by ∼ 50–75 mg/dL. 
Prothrombin complex concentrate (PCC) 
- Vitamin K antagonist-associated major bleeding: 4-factor PCC is given with IV vitamin K (see “Warfarin reversal” for further information). 
- Treatment and prevention of bleeding in patients with rare clotting factor deficiencies if specific factor preparations are not available 
- Consider for the in life-threatening bleeding. 
- Adverse effects
Single-factor concentrates 
- Content: specific clotting factors that have been pooled from multiple donors
- Indications: specific clotting factor deficiencies (e.g., factor VIII and factor IX are used for the treatment of hemophilia A and hemophilia B) if recombinant factors are not available
When possible, use recombinant synthetic factors over blood-derived clotting factors, as they are not associated with any risk of infection transmission. 
- Content: antithrombin III; , which is synthesized in the liver and inhibits coagulation factors IXa, Xa, XIa, and XIIa, and thrombin
- Effect: increases the effects of heparin
General principles 
- Emergency-release blood components can be issued from the blood bank in < 5 minutes but are associated with an increased risk of hemolytic transfusion reactions. 
- Unknown recipient blood type: Give universal donor blood products (blood products that could potentially be safely transfused to any recipient regardless of their ABO blood type, including blood type O negative packed RBCs, blood type AB plasma, and blood type AB platelets)
- Known recipient ABO type and Rhesus status: Give type-specific blood products.
Blood product selection 
- Unknown recipient blood type
- Known recipient blood type
- The replacement of a large volume of blood in response to
- There is no universal threshold for a massive transfusion; proposed values include: 
Giving patients large volumes of blood products, especially if unbalanced or given rapidly, risks the following :
- Coagulopathy 
- Electrolyte imbalances
- Citrate toxicity
- Transfusion-related lung injury
- Transfusion-associated circulatory overload
Judicious use of blood products to avoid is the best way to prevent !
Massive transfusion protocols (MTP) 
- Goal: mitigate the risks of massive transfusion 
- Clinical application: activated for patients with large volume transfusion requirements, e.g., due to trauma, major surgery, obstetric complications, GI bleeding
- Protocol components
- Initial approaches: Consider a fixed ratio approach or whole blood approach for patients with ongoing hemorrhage prior to laboratory results.
- Subsequent approach: Consider targeted transfusion regimen once laboratory results become available and/or is achieved.
The optimal approach to blood component transfusion for massive hemorrhage remains unknown. Follow local hospital protocol under specialist guidance.
Fixed ratio approach 
- Transfusion of RBCs, FFP, and platelets at predefined ratios
- Intended for prophylaxis and empiric treatment of coagulopathy
- Ratios vary by local protocols. Examples include:
Whole blood approach 
- Initial transfusion of whole blood (limited availability).
- Used as an alternative to the fixed ratio approach in the treatment of massive traumatic hemorrhage
- anti-A and anti-B antibody titers is used in emergency transfusions to minimize the risk of hemolytic transfusion reactions. with low
Targeted transfusion regimen 
- Requires frequent laboratory monitoring (e.g., every 1–2 hours)
- Thresholds and dosing vary by local protocols
- Consult transfusion services if available.
|Suggested thresholds for targeted transfusion in massive hemorrhage |
|RBCs|| || |
|Platelets|| || |
Massive transfusion protocol checklist 
- Activate the MTP, following local hospital guidance.
- Start monitoring, including continuous telemetry.
- Place 2 large-bore peripheral IV catheters.
- Obtain routine baseline massive transfusion studies, including CBC, PT, aPTT, serum fibrinogen, ionized calcium, BMP, and blood gases.
- Consider using point-of-care if available.
- Start transfusing blood through blood-warming equipment.
- Regularly reassess the patient to assess for signs of fluid overload and/or respiratory distress.
- Repeat massive transfusion studies, including arterial blood gases, at regular intervals.