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JULY 2017 | Published by RCPA

Issue #071

Donor Questionnaires provide vital information to blood services

Donor Questionnaires provide vital information to blood services

Blood donations are precious, which is why there are processes to ensure maximum benefit from every donation. Two experts from the Australian Red Cross Blood Service explained how they determine whether you can donate blood, and then control how it is used.

Dr Joanne Pink, Haematologist, and Chief Medical Officer/Executive Director of Clinical Services and Research at the Australian Red Cross Blood Service, said all blood donors must complete a Donor Questionnaire at every donation.

“This questionnaire asks about their medical history, medications, lifestyle behaviours and travel history. The answers are then used to determine the suitability of the person to donate blood and to establish the type of blood products that can be made safely from their donation,” she explained.

Donated blood is subjected to a series of mandatory tests to detect specific infections such as HIV, hepatitis B, hepatitis C, syphilis and a virus known as Human T-cell lymphotropic virus type 1 (HTLV1).

“These infections are known to be transfusion transmissible. We also carry out selective screening for cytomegalovirus (CMV) and malaria, both of which are infectious agents that can affect the way a donation is treated.”

Once these checks are out of the way and the blood is cleared for use, specialists at the Blood Service work out how each blood donation will be used.

“It is standard practice to separate the whole blood into its different components of red cells, white cells, platelets and plasma. White cells are usually removed from the donated blood by filtering prior to further processing (known as leucodepletion), as they are a common cause of side effects in recipients. The other components can then be transfused separately into different recipients as medically indicated to allow maximum benefit to be derived from each blood donation,” explained Dr Pink.

How these components are used depends on the Donor Questionnaire.

“Each blood component may be variably affected by different issues identified in the Donor Questionnaire and will have a different potential to transmit specific infections. Each component needs to be assessed independently regarding its quality and safety to determine if it can be released for transfusion.”

Dr George Kotsiou, Microbiologist and National Donor and Product Safety Specialist, provided some examples of how these assessment are made. “They also illustrate why it is important to provide full and honest disclosure on the Donor Questionnaire,” he said.

Medications and platelet transfusions

“Platelet transfusions are given to patients with very low platelet counts who are at risk of severe bleeding, but they cannot be made from donors who have taken medications that interfere with platelet function such as aspirin and ibuprofen,” Dr Kotsiou explained.

He said one effect of these drugs is to cause platelets to be less sticky so they are unable to form the stable plug necessary to stop bleeding. This effect lasts approximately 7 days for aspirin and 2 days for ibuprofen.

“For this reason, we don’t take platelets from donors who have taken medicines containing these or similar drugs within these time periods. Red blood cells and plasma products can still be used from these donations, as the quality of these components is not affected by these medications.”

CMV infection

Dr Kotsiou said approximately 60% of healthy Australians have had CMV infection in the past, although most of them won’t recall the mild illness associated with it.

“It often occurs in infancy and may be completely without symptoms. Infected individuals will then carry CMV for the remainder of their lives, generally without ill effect. The organism may subsequently be found in their blood, especially the white cells, despite the donor feeling completely well.”

In some rare groups of blood recipients, such as premature babies or severely immune suppressed individuals, CMV infection can cause a very severe, even a life-threatening, illness.

“This is why the Blood Service tests some donations for CMV antibodies, and keeps a separate inventory of blood products from donors who have tested negative for CMV antibodies. Whilst leucodepleted blood is widely considered to be CMV-safe, CMV antibody testing may provide further reassurance for the highest risk recipient groups such as babies still in the womb.”

Malaria

Malaria is a parasite that predominantly infects the red blood cells. Travellers to regions where malaria is present are at risk of becoming infected. This risk can be reduced but is not entirely eliminated by taking anti-malaria drugs or using mosquito avoidance measures. This is why donors who have returned from risk countries are routinely tested for malaria antibodies.

“Donors who present to donate within 120 days after travelling to a country at risk of malaria are initially only eligible to donate plasma. The plasma is then manufactured into various plasma-derived products rather than used fresh. The additional processing steps used in the manufacturing process are able to kill any malarial parasites, and many other germs as well if they are present, which makes the product safe.”

Dr Kotsiou says red cells and platelets cannot be used from people who have a history of travel to a destination with a known malaria risk, but those people are able to resume donating red cells and platelets when they have been cleared by malaria antibody testing.

Other infections

“The Blood Service is only able to actively test each donation for a relatively small number of infections. Often the Donor Questionnaire will identify a possible exposure to an infectious disease that is not screened for by the Blood Service, commonly as a result of travel to a risk area,” explained Dr Kotsiou.

He said these infections include dengue, chikungunya and West Nile (which are all viruses acquired through mosquitoes) that can sometimes cause minimal symptoms, or only cause illness to the donor after a donation has been given. This means asking donors for a history of illness prior to donation may not always identify an infection.

“For this reason, red cells and platelets are not used from donations from donors who have travelled to a country with a risk for these infections. Instead plasma donations can be sent for further processing and manufactured into plasma-derived products.”

Articles about blood and blood donations are also in the December 2016, October 2013, November 2011 and July 2011 editions of ePathWay.

 


 

 

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