Operational feasibility of routine bacterial monitoring of platelets.

Bacterial contamination of platelets poses the greatest risk of mortality and morbidity to platelet transfusion recipients. Some European countries have introduced routine bacterial monitoring of platelets to reduce the risk of transmission of bacteria. A pilot study was carried out at the Northern Ireland Blood Transfusion Service, using the BacT/ALERT automated culture system, to assess the operational feasibility of routine bacterial monitoring of platelets. About 4885 platelet concentrates (PCs) were tested in a 1-year period. Of the 28 (0.57%) initial reactive cultures, 13 (46%) were reproducible on repeat culturing. Of these, 10 were detected within 24 h of incubation either in aerobic or both aerobic and anaerobic culture bottles. A sample of time-expired units (423) that had initial negative culture results remained negative when retested on day 8. About 213 time-expired units were subjected to routine quality assessment and more than 85% were found to conform to quality standards specified in the UKBTS guidelines for platelet count (> or =240 x 10(9) per adult dose PC) and pH (6.4-7.4). There was a reduction in the platelet count because of the volume removed (15 mL) for sampling. Routine bacterial testing with day 2 sampling and a negative culture result after 24 h as a mandatory release criterion would improve product safety. Implementation of 100% testing would be operationally feasible but may require extension of the shelf life if unacceptable wastage is to be avoided.

The clinical outcome of non-RhD antibody affected pregnancies in Northern Ireland.

We assessed the clinical outcome of pregnancies with non-Rh-D antibody in Northern Ireland using retrospective case note review. During the study period (April 1999- March 2000) 186 women with clinically significant antibodies were identified from the records of the antenatal laboratory of the Northern Ireland Blood Transfusion Service. Eighty-five women were included in the study using the criteria mentioned above. None of the fetuses required intrauterine transfusion during this period. One baby required exchange transfusion, three were given top-up transfusions and 17 had phototherapy. Nine babies with a positive direct antiglobulin test (DAT) received no treatment. The incidence of anti-Kell could be reduced by transfusing Kell negative red cells to premenopausal women. It is important that all pregnant women are tested at least twice in their pregnancy to detect the antibodies formed late in the pregnancy. It is useful to formulate a standard protocol for antenatal interventions. Non Rh-D antibodies can cause significant anaemia for up to six weeks in the neonatal period, hence early detection of maternal antibodies is important so that the neonates are followed up for an appropriate length of time.

Hepatitis B virus infection in Northern Ireland 1970-1987.

In the 18 years between 1970 and 1987, 504 patients were found to have hepatitis B surface antigen (HBsAg) in their blood. Acute hepatitis was present in 184 patients and six died (3.3%). The annual incidence of acute hepatitis B virus infection in Northern Ireland was about one-quarter that of England and Wales. A decrease in acute infection occurred in 1986-87, while in England and Wales acute infection has fallen by more than half since the peak in 1984. Hepatitis B virus infection in health care staff and patients in high risk groups were reviewed: 32% were in those of foreign origin or who had known foreign contacts. In blood donors there was a marked fall in incidence of hepatitis B surface antigen carriage from 1982 onwards: the incidence in antenatal patients and those screened for rubella antibody (mainly females) was half that of new blood donors in 1972-81. Carrier rates in blood donors and antenatal patients were less than those from other parts of the United Kingdom. All indices show that Northern Ireland has a lower incidence of hepatitis B virus infection than the rest of the United Kingdom.

Increasing demands on today's blood donors.

Recently in Northern Ireland there has been a rapid increase in demand for a variety of blood components. To meet this need a large proportion of routine blood donations must be processed at the Transfusion Centre. In addition, several blood components are collected direct from donors by apheresis techniques. Apheresis is currently restricted to the collection of components from highly selected donors, but in future this method is likely to be employed for collection of some routine components. This changing pattern is placing increasing demands on many of our blood donors.