Look-back investigations are initiated on recognition that there may have been a risk of transmitting infection from a donor to a recipient. Such a situation may arise in the following circumstances:
National look-back investigations, following introduction of a new screening test, should be managed through a generic system which incorporates the following steps:
Look-back investigations following identification of a donor who has seroconverted and/or been responsible for transmission of infection and/or is identified through post-donation information should be carried out using the same principles.
Wherever possible, retrospective testing of stored samples should be carried out in order to identify those donations which must be included in the look-back. If samples can be tested, look-back should be performed to include the last seronegative donation, unless there is evidence about the timing of infection which would make such action unnecessary, e.g. a documented negative test result after the last negative blood donation, a clear history of risk exposure post-dating the last seronegative donation etc.
If retained samples are not available for testing, then case-by-case decisions on the number of donations to be included in the look-back will be influenced by the dates of donations and the availability of the particular hospital transfusion records.
All cases of look-back should be documented in the same fashion as investigation of TTI. There should be a full audit trail of decisions made and actions taken.
Where look-back results in the identification of infected recipients, a report should be made to the surveillance system as appropriate, and cases included in the annual SHOT report.