BOF: Transfusion (Haematovigilence)

A patient requires a blood transfusion for treatment of chronic blood loss of hereditary haemorrhagic telangiectasia (HHT). Their last transfusion was four months ago. According to the British Committee on Standards in Haematology (BCSH) and the National Blood Service (NBS) what is the longest time that can have elapsed since their last blood sample for atypical red cell antibody screening (pretransfusion testing).

a) 24 hours

b) 48 hours

c) 72 hours

d) 7 days

e) 14 days

Answer:

d) 7 days

Explanation:

To maximise the chance of detecting clinically significant red cell antibodies with repeat blood transfusion, antibody screening should be performed at a time prior to a new transfusion depending on when the previous transfusion occurred. Although initial sensitisation takes 4-6 weeks, restimulation can lead to the emergence of clinically significant antibodies within 3 days. Hence, if the last transfusion was 15-28 days ago, the screen should not be >72 hours old. If greater than 28 days have elapsed, guidelines suggest that the screen could be up to 7 days old, although the latest guideline suggests this policy should be seen as a formal deviation from the 3-day rule for chronically transfused patients with no alloantibodies.

If the transfusion was 3-14 days ago, previous UK guidelines required that the screen should not be >24 hours old, however a recent UK guideline revision has amended this in light of national and international evidence (in some jurisdictions, e.g. Canada, 96 hours is deemed acceptable for any patient transfused within the last month) that the longer duration did not lead to excess harm. Hence 72 hours maximum time between last antibody screen and transfusion of the selected unit is now deemed universally acceptable.

Reference:

Milkins C, Berryman J, Cantwell C et al. Guidelines for pre-transfusion compatibility procedures in blood transfusion laboratories. British Committee for Standards in Haematology. British Committee for Standards in Haematology, Transfus Med. 2013 Feb;23(1):3-35.