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Date: 10 December 2014
All Transfusion Laboratory Managers and Transfusion Practitioners in
hospitals served by NHSBT
Dear Colleagues
Hb S negative results for donations bled 26/10/14 to 02/12/14 inclusive
NHSBT has determined that for a period between Oct 26- Dec 2 inclusive the reagent used
for sickle screening of donor red cells in one of our testing centres should have been
removed from use. This means that we cannot assure the validity of all of the ‘HbS negative’
results on the pack labels from units collected between these dates. From donations bled
from 3rd December new reagents were used and the test results are valid; thus units
donated from this date onwards are not affected.
The risk is of a false negative Hb S result on the label. The risk of this is assessed as very
low. All donors from Black, Asian and Minority Ethnic (BAME) backgrounds are tested as
well as some ethnic white donors; less than 2% of all donations come from BAME donors
and the percentage expected to be positive in BAME donors is less than 1:20. (All positive
sickle cell screening results are sent for confirmation and the positive results from our
screening during this time have been confirmed as correct). Thus the vast majority of
donations labelled ‘Hb S negative’ will be true negatives irrespective of testing. In addition
this was only a problem in one or our testing centres.
The groups for whom sickle negative red cells are routinely supplied are patients with sickle
cell disease and fetuses/neonates/infants. Transfusion of sickle trait red cells would be
unlikely to have a significant clinical impact for patients without sickle cell disease, including
for neonatal/infant large volume transfusion, although it should be avoided if possible for
intrauterine and neonatal exchange transfusion. The clinical risks to patients with sickle cell
disease is that top up and exchange transfusions in adults and children may be slightly less
effective than expected in reducing HbS levels. This risk would be higher in smaller
recipients eg children. HbS levels should be routinely measured before and after transfusion
in patients with sickle cell disease. The risk of less effective reduction of HbS levels following
transfusion is very low.
Recommended Action for Current Transfusions
1.Planned transfusions of children or adults with sickle cell disease requiring less than two
units of red cells – hospitals should request units bled on or after 3rd December 2014.
2.Emergency transfusions in patients with sickle cell disease – if alternative suitably matched
blood is available then use. If the only immediate blood available is from the affected time
period the risk of not transfusing should be balanced against the very low risk of not being
assured of the HbS result as the former may significantly outweigh the latter. Hospital
clinicians may consider testing the unit for HbS if readily available in their own laboratory
or transfusing empirically.
NHS Blood and Transplant is a Special Health Authority within the National Health Service
3.Fetal/neonatal/infant large volume transfusions, including neonatal exchange transfusions,
are recommended to be with units within 5 days of donation. Units of this age will now
have been bled on or after 3rd December 2014 so will be unaffected. For
urgent/emergency large volume transfusion of neonates and infants, if the only available
units are from the affected time period, the risk of not transfusing should be balanced
against the very low risk of not being assured of the HbS result as for emergency
transfusion of patients with sickle cell disease above.
4. All other clinical situations – no action required
NHSBT will be confirming whether any units for intrauterine or neonatal exchange
transfusion could have been affected and will inform the relevant hospitals if so.
Any clinician requiring further advice should contact NHSBT consultants who are available
24 hours via Hospital Services.
If you have any queries please contact an NHSBT Consultant, Customer Service Manager
or Hospital Services Manager. Alternatively please contact the Customer Service Response
Desk on 0208 201 3107 between 08:30 to 16:30, Monday to Friday.
Please notify your Consultant with responsibility for the transfusion laboratory of this
Yours sincerely
Teresa Allen
Assistant Director – Customer Services
email: teresa.allen@nhsbt.nhs.uk
Dr Kate Pendry
Clinical Director – Patients
email: kate.pendry@nhsbt.nhs.uk
NHS Blood and Transplant is a Special Health Authority within the National Health Service