Pretransfusion specimen collection and compatibility testing

The collection of the pretransfusion specimen is a critical task that if not performed correctly could lead to an incompatible transfusion and potentially fatal reaction.

Failure to perform positive patient ID processes at the time of specimen collection continues to be a significant cause of preventable patient harm.

Each health service must have written procedures in place for accurate patient identification and specimen collection.

A correctly labelled pretransfusion blood specimen collected from the intended recipient is an essential step in preventing errors. Pretransfusion specimens that do not conform will be rejected and discarded by the Transfusion Service Provider.

Important practice points for specimen collection

Specimen collection is a critical task, and staff should not be interrupted during this process.

The patient must be positively identified.
Only bleed one patient at a time.
Never pre-label the specimen tubes.
Unlabelled specimens must not leave the patient’s side.
Electronic systems and medical records must not force labelling away from the bedside.

Follow health service procedures for patient identification and specimen labelling, including the specific workflow for the electronic system(s), if these are in place.

Ask the patient (where possible) to state/spell their full name and state their date of birth.
- Check these details along with the hospital unique identification number against the identification band (if available – refer to health service policy).
- A family member/carer can assist in verifying patient information if the patient is unable to do so themselves.
Check that the above details are identical to the details on the request form (EMR or paper).
Label the specimen immediately after collection and before leaving the patient with the following details (or as required by health service policy):
- patient’s surname and given name in full
- date of birth and unique patient identification number (or at least one of these AND an additional approved identifier as required by health service policy)
- date and time of collection.
Confirm that the blood specimen, request form and patient details all match.
Sign/initial both the blood sample and the request form to verify correct patient identification.
Complete and sign (or initial) the declaration on the request to verify the specimen was collected from the correctly identified patient.

Specimen validity

Specimen validity refers to the period when a pretransfusion sample may be held for testing and used to provide crossmatched blood.
Specimen 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 specimen collection, the specimen will normally have a validity of 72 hours. This is known as the 72-hour rule.
A new specimen will need to be collected once 72 hours elapse if further transfusion is required.
Longer expiry times are often applied if the patient does not have a history of transfusion or pregnancy in the preceding 3 months or in certain clinical situations.
Contact your Transfusion Service Provider for their policy on specimen validity and retention.

Pretransfusion testing

Blood group and antibody screen

Determining the patient’s ABO group and performing an antibody screen to detect clinically significant red cell antibodies are essential elements of pretransfusion testing.

A blood group and antibody screen (also known as a “group and screen” or “group and hold”) includes the following:

ABO and RhD typing of the patient's red cells
antibody screen to detect antibodies in the patient's plasma
identification of red cell antibodies (if the patient has a positive antibody screen), and
crossmatching appropriate donor red cells

Before testing takes place, the laboratory staff will:

Confirm that the patient’s details on the specimen and request form are identical.
Check for historical information on the patient, such as previous blood group, previous transfusion and obstetric history.

Compatibility testing

Compatibility testing (or crossmatching) is performed to prevent transfusion of incompatible donor red cells, which could result in a haemolytic transfusion reaction. The ABO blood group is the most important in transfusion and compatibility testing.

A crossmatch may be performed by either serological or electronic methods. An electronic crossmatch is performed by computer, whereas the immediate spin and indirect antiglobulin test crossmatches are serological methods, physically testing the recipient's plasma against donor red cells.

Electronic crossmatch (eXM)

ABO compatibility between the patient and donor red cells is checked “virtually” by the laboratory information system (LIS) and not by serological testing.
Can only be used if the patient currently has no clinically significant antibodies, and there’s no history of clinically significant antibodies.
Red cells can be crossmatched and issued with minimal delay once the blood group and antibody screen are completed.
Specific criteria must be met before electronic crossmatching can be used (refer to ANZSBT Guidelines for transfusion and immunohaematology laboratory practice).

Immediate-spin crossmatch (IS XM)

The IS XM is a simple serological test used to test for ABO compatibility between the patient’s plasma and donor blood.
The IS XM can be used as a backup method of testing when eXM systems are unavailable or in smaller regional laboratories that don't yet have a validated LIS capable of eXM.
Can only be used as the sole compatibility test if the patient currently has no clinically significant antibodies, and there’s no history of clinically significant antibodies.

Indirect antiglobulin test crossmatch (IAT XM)

The IAT XM is a serological test which uses the same technique as an IAT antibody screen.
Generally used when crossmatching patients who have a clinically significant (IgG) red cell antibody or have a history of one.
The patient’s plasma is crossmatched against donor blood negative for the antigen against which the antibody is directed.

Updated January 2026