Blood Transfusion Lecture Notes

Blood Transfusion Overview

• Speaker: Catherine Lorenzen, Chief Biomedical Scientist

• Institution: EKHUNHSFT

Donated Blood Testing in the UK

• Types of Agents and Testing Initiated:

  • Hepatitis B Virus (HBV): Tested since 1969/70, using HBsAg; Window period: 75 days

  • Hepatitis C Virus (HCV): Tested since 1991, using Anti-HCV and HCV NAT; Window period: 14 days - 6 months

  • HTLV (Human T-Lymphotropic Virus): Tested since 2002 using Anti-HTLV (1 and 2); Not well characterized

  • HIV: Tested since 1985, using Anti-HIV (1 and 2); Window period: 22 days

  • Hepatitis E Virus (HEV): Tested since 2017 using RNA testing; Window period: 14 - 70 days

  • Syphilis (Treponema): Tested since 1946 using TPHA; Window period: 14 days

Limitations of Blood Testing

• Window Periods: The span during which a donor can be infected without the tests detecting the infection.

• Even in an ideal testing environment, there's a risk of transmission due to undetected window period infections.

Safety Measures in Transfusion

• Donor Selection:

  • Questionnaires are used to assess risk factors (recent tattoos, piercings, medical conditions).

  • Temporary or permanent deferral for high-risk candidates.

  • Emphasis on truthfulness from donors, as they are non-paid volunteers.

  • Highlights the balance between donor safety and infection transmission risk.

Conservative Transfusion Practices

• Transfusion Approach:

  • Aim to minimize unnecessary transfusions by evaluating if one unit suffices instead of two.

SHOT 2023 Data on Transfusion-Transmitted Infections (TTIs)

• Cited data on confirmed TTIs in the UK from various infections over the years, such as

  • Parvovirus, vCJD, HBV, HIV, and more, with descriptions detailing the year, type of infection, and the number of cases.

• Total incidents documented and their outcomes to understand risks better.

Residual Risk of Viral Infections Post-Transfusion

• Infection Risks:

  • HBV: 1 in 1.3 million

  • HIV: 1 in 6.5 million

  • HCV: 1 in 28 million

• Observations on historical cases of HEV, HBV, HCV, and HIV reflecting improved safety measures and risk mitigation strategies.

Bacterial Infections in Blood Transfusion

• Early complication recognition, with reduced prevalence due to

  • Sterile techniques, closed systems, and proper blood storage.

• Storage Practices:

  • RBC: stored at 4ºC to limit bacterial growth; storage duration 5 weeks.

  • Platelets may pose a higher risk due to storage conditions (20-22ºC).

• Reports indicate cases of bacterial transmission, with 11 deaths in documented instances and a focus on the need for stringent donor selection and hygiene protocols.

Covid-19 Considerations in Blood Donation

• Vaccination data not tracked in donors, with recommendations to ensure donor health and safety following vaccination.

• Antibody presence in donated blood doesn’t affect COVID transmission risk.

Laboratory Detection Role

• Importance of inspecting blood components before issuance for contamination or unusual appearance.

• Practices involve returning suspected infected components for further investigation and culture.

Other Transmissible Infections

• Risks from Known and Possible Infections:

  • Malaria, Trypanosomiasis, various Hepatitis viruses, and more.

• Regularly assessing donor travel history to endemic areas for malaria and other diseases.

Future Safety Measures

• Suggested improvements include more rigorous testing protocols and pathogen inactivation methods.

• Emphasis on reducing transfusion volumes as the most effective risk management strategy.

Conclusion

• Educational tool suggesting a guided tour of the NHS Blood and Transplant Centre for further understanding of transfusion practices and safety measures.