Timing of sample collection
All patients requiring blood components must have transfusion samples taken on 2 or more separate occasions.
Transfusion or pregnancy may cause either a primary or secondary immune response and samples selected for cross-matching or antibody screening must take account of this so that any newly developed antibodies are detected.
In situations in which patients are being repeatedly transfused a daily sample is not a requirement.
Patients should be screened for the development of irregular antibodies every 72 h.
A new sample less than 72 hours from time of transfusion is required for cross-match purposes.
It is recognised that for some individuals, e.g. thalassaemic patients who are repeatedly transfused and who have not had an antibody response, a more tolerant approach may be taken.
Samples used for pre-transfusion testing should never be more than 7 days old. Where possible, it is advisable that a sample taken immediately before transfusion is available for retrospective testing in the event of a transfusion reaction occurring.
In cases where an Antenatal patient is to receive a Intrauterine Transfusion (IUT) at St Michael’s hospital in Bristol, a sample can be taken at RD&E and the request form labelled:
‘Sample to be sent to NBS Bristol, Patient to receive IUT at Bristol Hospital on ……’
This will be sent by the Transfusion laboratory up to the reference lab the day before the patient is admitted to St Michael’s Hospital, allowing a special unit of blood to be provided promptly.
