Compatibility
Red Cells
- Should give ABO compatible Packed Cells (see table below)
- If recipient has atypical antibodies, need to do serological crossmatch
Platelets
- Should give ABO matched platelets
- If it is necessary to provide platelets other than the patient’
s own blood group, the patient’
s age, diagnosis, therapy, component type availability (ie apheresis platelets vs pooled platelets) as well as any special circumstances (eg HLA matched) may influence the decision to give either antigen-incompatible or antibody-incompatible platelets
- If an ABO antigen compatible/plasma incompatible platelet transfusion (eg group A patient given group O platelets) is given
- The recipient may develop a positive direct antiglobulin test (DAT) which may result in haemolysis
- 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 antigen incompatible/plasma compatible platelet transfusion (eg group O RhD negative patient given A RhD positive platelets) is given
- The post-transfusion platelet increment and platelet survival may be lower in some patients
- Sensitisation to foreign
red cell antigens
and in particular RhD may also occur
FFP and cryoprecipitate
- Should be compatible with ABO group of recipient to avoid potential haemolysis caused by donor anti-A or anti-B
ABO component compatibility table
|
| Red cells | Platelets | Plasma components |
| Patient group unknown | O# | A or O (low titre anti-A/B) | AB* |
| Patient group O |
| First choice | O | O | O |
| Second choice |
| A** | A or B |
| Third choice |
| AB | AB |
| Patient group A |
| First choice | A | A | A |
| Second choice | O | O (low titre anti-A/B) | AB |
| Third choice |
| AB or B, O |
|
| Patient group B |
| First choice | B | B | B |
| Second choice | O | O (low titre anti-A/B) | AB |
| Third choice |
| AB or A, O |
|
| Patient group AB |
| First choice | AB | AB | AB |
| Second choice | A or B | O (low titre anti-A/B) | A* |
| Third choice | O | A or B, O |
|
# If patient is a female of child bearing potential, O RhD negative red cells should be used until patient’
s blood group is established.
* Group A plasma may be used as per local institutional policies.
** Group A platelets that have an A2 subgroup do not express significant amounts of A antigen and are, therefore, compatible with group O recipients.
Compatibility Testing
Group and Hold / Type and Screen
- ABO and RhD
typing of recipient's red cells
- Atypical antibody screen to detect antibodies in recipient's plasma
- Identification of
red cell antibodies
(performed if positive antibody)
screen detected
- Crossmatching appropriate donor
red cells
Crossmatch
- Crossmatching is used to confirm compatibility between the patient's blood (plasma)
and the donor red cells
- This may be performed by either serological or electronic methods
Serological Crossmatch
- Indirect antiglobulin technique (IAT)
- Generally used when crossmatching for patients with clinically significant IgG antibodies.
- Patient's plasma is incubated with donor red cells and tested.
- Immediate spin crossmatch
- Designed to detect ABO incompatibilities between donor red cells and recipient plasma.
- Only used if patient currently has no clinically significant antibodies, and there is no history of clinically significant antibodies
- Patient's plasma is tested against donor red cells
Non serological crossmatch
- Electronic (Computer) crossmatch
- ABO compatibility of patient and donor
red cells is checked by the laboratory information system (LIS) with no serological crossmatch tests needing to be performed
- Only used if patient currently has no clinically significant antibodies, and there is no history of clinically significant antibodies
- Allow red cells to be issued with minimal delay once blood group and antibody screen completed
- Specific criteria must be met in order to utilise electronic crossmatching (refer to
ANZSBT guidelines )
- Many hospitals now use electronic crossmatch unless atypical antibodies are detected, meaning that there is no need to ask for a crossmatch, over a group and hold, unless there are atypical antibodies
The 72 hour Sample Validity Rule
- Sample validity refers to the period
when a
pretransfusion sample may be held for testing and used to provide crossmatched blood
- Sample validity period
depends on the patient's transfusion and obstetric history.
Red cell antibodies can rapidly appear in response to stimulation by transfused red cells or as a result of pregnancy
- If the patient has been transfused with red cells, or is currently (or has been) pregnant in the 3 months preceding pretransfusion sample collection, the sample will have a validity of 72 hours. This is known as the 72-hour rule
- A new sample will need to be collected once 72 hours elapses if further transfusion is required
- Longer expiry times are often applied if the patient does not have a history of transfusion or pregnancy
Incidence of haemolytic reactions
| Extent of testing | Relative Safety |
| ABO compatible blood | 99.4% |
| plus Rhesus compatible | 99.8% |
| plus negative antibody screen | 99.94% |
| plus Coombs test (IAT) | 99.95% |