SHOT Annual Report 2009 - Serious Hazards of Transfusion

16. Post-Transfusion Purpura (PTP)
Definition
Post-transfusion purpura is defined as thrombocytopenia arising 5–12 days following transfusion of red cells
associated with the presence in the patient of antibodies directed against the HPA (human platelet antigen)
systems.
Two questionnaires were received but both were withdrawn because neither had alloantibodies directed against HPA.
Cumulative data 1996–2009
Figure 19 shows reports to SHOT since 1996 of the annual numbers of cases of PTP with confirmed HPA alloantibodies: a
total of 46 reports. A sustained decrease in the number of these cases has been seen since the introduction of universal
leucodepletion in late 1999.
Since 1996, platelet antibodies with specificity for HPA-1a have been the most frequently identified. Thirty-six patients
(78%) have had HPA-1a antibodies either alone (31 cases) or in combination with other antibodies (5 cases). In 10
cases PTP was due to other HPA antibodies without HPA-1a. These included antibodies with specificity for HPA-1b, -2b,
-3a, -3b, -5b and 15a, of which HPA-1b and HPA-3a antibodies were found most frequently (5 cases each). HPA-5b
antibodies were found in only 1 case. All except one of the cases with non-HPA-1a antibodies were reported before the
introduction of universal leucodepletion in 1999.
Figure 19
Number of cases of confirmed PTP reported to SHOT each year
12
11
10
Number of cases
9
8
7
6
5
4
3
2
1
0
1996–97
1997–98
1998–99
1999–00
2000–01
2001–02
(15 months)
2003
Year of report
2004
2005
2006
2007 2008 2009
Further information about PTP is available in Practical Transfusion Medicine. 46
RECOMMENDATIONS
Clinicians are encouraged to contact Blood Services if they suspect PTP.
Recommendations still active from previous years
■■
Clinicians need to maintain awareness of this rare but treatable complication of transfusion.
16. Post-Transfusion Purpura (PTP) 127