What is the importance of the ABO compatibility table?

Patients should receive ABO-identical blood products whenever possible, however sometimes it may be necessary to provide ABO-compatible blood products instead.

The table below lists the acceptable blood group choices in order of preference.

ABO component compatibility table

Patient ABO group unknown

Group O patient

Group A patient

Group B patient

Group AB patient

[a] If the patient is a female of childbearing potential, O RhD negative red cells should be used until the patient’s blood group is established. 
[b] Group A platelets with the A2 subgroup don’t express significant amounts of A antigen and are therefore preferable to other group A platelets when transfusing group O and B recipients. 
[c] Apheresis platelets that have a low titre anti-A/B or pooled platelets pose a lower risk of haemolysis when transfusing ABO incompatible components. 
[d] Plasma components that have low titre anti-A/B pose a lower risk of haemolysis when transfusing ABO incompatible components. 
[e] Group A plasma may be used as per local institutional policies.

Clinical information

You should always refer to your local hospital policies and seek advice from a Consultant Haematologist, your Transfusion Service Provider or a Lifeblood Transfusion Medicine Specialist or Scientist when transfusion of components other than the patient’s own blood group is necessary. This should definitely happen in emergency situations or when stocks are limited or unavailable.

Incompatible transfusions can result in serious harm or death of the patient. 

Red cell compatibility

Pretransfusion testing is required for the release of compatible red cells. Consult your Transfusion Service Provider about your requirements for samples and request forms.

RhD

Group RhD negative red cells can be transfused to RhD positive recipients safely, however transfusing RhD negative recipients with RhD positive red cells can result in the formation of anti-D.

The following patient groups should receive RhD negative red cells:

• RhD negative patients with anti-D 
• RhD negative females of childbearing potential 
• females of childbearing potential with unknown blood group (in an emergency) 
• RhD negative children (males and females <16 years), and 
• RhD negative patients who will receive repeated transfusions, or are likely to become transfusion-dependent. 

Some regional and smaller metropolitan hospitals may only hold Group O RhD positive red cells for emergency use only (e.g. in life-threatening situations). 

Kell

Kell system antibodies should be considered clinically significant and are known to cause both transfusion reactions and haemolytic disease of the fetus and newborn (HDFN).  The Australian and New Zealand Society of Blood Transfusion and Lifeblood have issued a joint Consensus statement on use and allocation of Kell negative red cells in which the following recommendations have been made.

Clinical scenarios where K negative red cells are indicated (listed in priority order) include:

• Any patient with (or a history of) anti-K.
  Transfusion of pregnant females or females of childbearing potential who are K negative (∼90% of women). 
• Transfusion of pregnant females or females of childbearing potential who are unable to be phenotyped prior to transfusion. The clinical urgency of transfusion should be considered and emergency transfusion should not be delayed by attempts to source K negative units. 
• Patients who will be undergoing daratumumab therapy who are K negative or unable to be K phenotyped (or genotyped).

K negative units may be clinically indicated in the following scenario: 

Transfusion-dependent patients who are shown to have a K negative phenotype (∼90% of patients).    

Platelet compatibility

If it’s necessary to provide platelets other than the patient’s own blood group, the clinical scenario, component availability (pooled vs apheresis) and for special components (HLA matched), may influence the decision to give either antigen-incompatible or antibody-incompatible platelets.

If an ABO compatible/plasma incompatible platelet transfusion (e.g. group A patient given group O platelets) is given, the patient may develop haemolysis and a positive direct antiglobulin test (DAT). This is of greater importance in children as they have lower levels of soluble A and B substance in their body fluids.

If an ABO and/or RhD incompatible/plasma compatible platelet transfusion (e.g. group O RhD negative patient given A RhD positive platelets) is given, the post-transfusion platelet increment and platelet survival may be lower than expected in some patients. Sensitisation to residual red cell antigens, in particular RhD may occur. 

Prophylactic RhD immunoglobulin may be indicated when RhD positive platelets are transfused to an RhD negative patient, particularly in female children or women of childbearing age. Contact your Transfusion Service Provider or haematologist for further advice.  

Plasma compatibility

Plasma components (e.g. fresh frozen plasma, cryoprecipitate and cryodepleted plasma) should be compatible with the ABO group of the recipient to avoid potential haemolysis caused by donor anti-A or anti-B. Plasma components of any RhD type can be given regardless to the RhD type of the recipient. RhD immunoglobulin is not required in these situations.