What is Transfusion Medicine and National Blood Transfusion Service of Sri Lanka. Basics of Donor screening at the blood bank.

1. Transfusion Medicine
An Introduction
MATHURANGE KRISHNAPILLAI
MBBS, DTM, MD TRANSFUSION MEDICINE
(ACTING)CONSULTANT TRANSFUSION PHYSICIAN

2. What is it?
 Transfusion medicine is a multidisciplinary science concerned with the proper
use of blood or blood products in the treatment or prevention of disease.
 Optimal transfusion therapy requires knowledge of blood types and
crossmatching procedures, donor selection, blood collection and
administration techniques, component therapy, transfusion reactions, and
red blood cell (RBC) substitutes.

3. National Blood Transfusion Service
 Centrally coordinated
 Under the Ministry of Health
 Cluster centers
 Blood banks
 Consultants, MOICs, MOs, PHIs MLTs/MLSs, NOs, Health Assistants, Lab orderlies

4. What do we do?
 Select donors
 Collect blood
 Screen blood
 Prepare and store components
 Do Pre-transfusion testing
 Issue blood and components
 Investigate reactions
 Clinical transfusion medicine
 Therapeutic plasmapheresis/ PRP clinic
 Other special investigations

5. Blood Donation
 Even with all of today’s technology, there is no substitute for blood.
Blood is always needed for,
 accident victims
 cancer patients
 blood disorder patients
 surgery patients
 Pre-mature, pre term babies
 and many others…….
Someone has to give blood in order for someone to receive blood!

6. Who can donate?
Basic criteria
 Age above 18 below 60 years
 Weight above 50 Kg
 Hemoglobin above 12.5 g/dl
 Healthy
 Safe life style
 Donor selection criteria
1. Donor safety
2. Recipient safety

7. Blood donation process
 Education
 Donor declaration
 Donor selection and Haemoglobin estimation
 Donor registration
 Blood collection

9. Donor screening
 Blood group- ABO and Rh D
 Transfusion transmittable infections
Virus Bacteria Parasites
Tested for
 HIV 1& 2, Hep B, Hep C, Syphilis, Malaria

10. Who is a Blood donor
 A hero
Voluntary nun-remunerated
Regular donor
 Frequency of donation
whole blood 4 monthly
aphaeresis 2 weekly
 Body recovers the Blood very quickly:
 Blood plasma volume– within 24 - 48 hours
 Red Blood Cells – in about 3 weeks
 Platelets & White Blood Cells – within minutes

11. Cells
• Red cells
• White Cells
• Platelets
Plasma
• Fresh frozen plasma (FFP)
• Cryo-precipitate
Blood Components

12. Questions?
 Assignment 01
1. What is a temporary deferral?
2. What is a permanent deferral?
3. Mention 5 temporary deferral and 5 permanent deferral criterias when
selecting blood donors?
Email the answers to mkrishnapillai@yahoo.com before 25.01.2021 with,
1. Your name
2. Roll number

13. Screening Blood Donors
Donor testing,
1. Blood group
2. Transfusion Transmitted Infections

14. Blood Grouping- EDTA sample
 Major blood group system: ABO
 Rh- D
 Checking for Donor’s antigens and antibodies
 Forward and reverse grouping- reciprocal relationship

15. Steps
Required Reagents:
 Anti A, Anti AB, Anti B and Anti D antisera
 A1 cells, B cells, O cells
Sample: EDTA- 1-2 ml
EDTA sample
 Separate cells and plasma
 Prepare 3-5% cell suspension
Tubes: 7, Centrifuge/ cell washer
 Label as: Anti A, Anti AB, Anti B, Anti D, A cells, B cells, and O cells

16. Antisera

17. Reagent red cells

18. Steps
Anti A Anti AB Anti B Anti D O cells
B cells
A1 cells
 Forward grouping: 1 drop of antisera to each relevant tube and 1 drop of patient cells
 Reverse grouping: 2 drops of plasma and one drops of relevant reagent red cells
plasma
3-5%
cells
Forward grouping Reverse grouping

19.  Low spin- 500-1000g speed for 15 sec in the centrifuge and read.
 Forward: 3+ or more, Anti D- 2+ or more
 Reverse: 2+ or more

22. Blood
Group
Anti A Anti AB Anti B Anti D A1 cells B cells O cells
A+ + + 0 + 0 + 0
B+ 0 + + + + 0 0
AB+ + + + + 0 0 0
O+ 0 0 0 + + + 0
A Neg + + 0 0 0 + 0
B Neg 0 + + 0 + 0 0
AB Neg + + + 0 0 0 0
O Neg 0 0 0 0 + + 0

23. TTI
 The provision of safe and efficacious blood and blood components for transfusion
or manufacturing use involves a number of processes.
 From the selection of blood donors and the collection, processing and testing of
blood donations to the testing of patient samples, the issue of compatible blood
and its administration to the patient.
 There is a risk of error in each process in this “transfusion chain” and a failure at
any of these stages can have serious implications for the recipients of blood and
blood products.

24.  Screening for transfusion-transmissible infections (TTIs) to exclude blood
donations at risk of transmitting infection from donors to recipients is a critical
part of the process of ensuring that transfusion is as safe as possible.
 Effective screening for evidence of the presence of the most common and
dangerous TTIs can reduce the risk of transmission to very low levels
 Virus, bacteria, parasites
 All donations must be screened

25. The microbial agents of importance to blood transfusion services are those that are
transmissible by blood transfusion and can cause morbidity and mortality in
recipients. In order to be transmissible by blood, the infectious agent or infection
usually has the following characteristics:
 Presence in the blood for long periods, sometimes in high titres
 Stability in blood stored at 4o ⁰C or lower
 Long incubation period before the appearance of clinical signs
 Asymptomatic phase or only mild symptoms in the blood donor, hencenot
identifiable during the blood donor selection process

26. WHO:
 Mandatory screening to be done by all the nations:
1. HIV 1&2
2. Hep B
3. Hep C
4. Syphilis
Other infections: according to the country’s status
Sri Lanka: Malaria

27. 1/100
1/1,00
0
1/10,000
1/100,000
1/1,000,000
Adapted from Transfusion 2000; 40:143-159

28. One or a combination of markers of infection can be used to detect a particular
infection during the screening process. Various assay systems developed for
blood screening detect:
• Antibodies that indicate an immune response to the infectious agent
• Antigens that are produced by the infectious agent and indicate the
• presence of that agent
• Nucleic acid (RNA/DNA) of the infectious agent.

29. Types of screening assays
The main types of assay used for blood screening are:
Immunoassays (IAs):
— Enzyme immunoassays (EIAs)
— Chemiluminescent immunoassays (CLIAs)
— Haemagglutination (HA)/particle agglutination (PA) assays
— Rapid/simple single-use assays (rapid tests)
Nucleic acid amplification technology (NAT) assays.
Appropriate evaluation is required in selecting the type of assay for each TTI, based on critical
assay characteristics, such as sensitivity and specificity, as well as cost and ease of use.

30. Immunoassays
 to detect antibody, antigen or a combination of the two
 use of immobilized antigen which captures any specific antibody present in the
test sample (indirect IA)

31. Enzyme immunoassays (EIAs) and chemiluminescent immunoassays (CLIAs)
 Most used assays
 color generation in EIAs and measuring light produced by a chemical reaction in
CLIAs.
 suitable for the screening of large numbers of samples and require a range of
specific equipment.

32. Particle agglutination assays
 detect the presence of specific antibody or antigen in a test sample through the
agglutination of particles coated with the complementary specific antigen or
antibody respectively.
 particles including red cells (haemagglutination) and inert particles such as
and latex.
 do not involve multiple steps or need wash equipment

33. Rapid/simple single-use assays (rapid tests)
 discrete, individual, disposable assays
 based on a form of immunochromatography in which the added sample flows
down an inert strip and reacts with previously immobilized reagents
 positive reaction is visualized as a dot or a band appearing on the device strip
 simple-to-use formats
 not suitable for screening large numbers of blood samples

34. Nucleic acid amplification technology
assays
 detects the presence of viral nucleic acid, DNA or RNA, in donation samples
 a specific RNA/DNA segment of the virus is targeted and amplified in-vitro
 amplification step enables the detection of low levels of virus in the original
sample by increasing the amount of specific target present to a level that is easily
detectable.
 performed on individual donations (ID) or on mini-pools (MP)

35. Selection of Assays
Each screening system has its advantages and limitations that should be taken into
consideration when selecting assays. Some limitations include:
 The length of time following infection before the screening test becomes reactive
(window period)
 Rates of biological false positives which may result in the wastage of donations
and unnecessary deferral of donors
 The complexity of some systems that require automation.

36.  HIV-1 and HIV-2: Serological markers:
— anti-HIV-1, + anti-HIV-2
— HIV p24 antigen (p24 Ag)
— Viral nucleic acid: HIV RNA.
 Hepatitis B: Serological markers:
— Hepatitis B surface antigen
— Hepatitis B core antibody, in some situations
— Viral nucleic acid: HBV DNA.
 Hepatitis C: Serological markers:
— HCV antibody
— HCV antigen
— Viral nucleic acid: HCV RNA.
 Syphilis (Treponema pallidum):
— screening for specific treponemal antibodies-TPPA/TPHA
— Nonspecific- VDRL/RPR
 Malaria-
— Thick and thin slides
— Malarial Ag/abs

37. Risk of transmitting infection to recipients has been drastically reduced in the past
decades, due to
 Improved donor selection
 Sensitive serologic screening assays
 Application of viral inactivation procedures during manufacturing of plasma
products

38. Residual Risk
 Major sources of remaining risk are:
1. Window period donation
2. Viral variants not detect by current assays
3. Immunosilent donor
4. Laboratory testing error

39. Residual Risk
 The greatest threat to the safety of blood supply is the donation by seronegative
donors during the infectious window period
 Window period donation account for 90% or more of the residual risk (Report of
the Interorganization Task Force on NAT Testing of Blood Donors, 2000)

40. Window Period
 Period precedes the development of antibodies during the initial infection
 Eclipse phase of the window period - the very initial phase after exposure when
virus replication is restricted to tissue sites and there is no detectable viraemia
 Infectious phase of window period is after eclipse and before seroconversion

42. Residual Risk
 Risk of acquiring a transfusion-transmitted viral infection depends not only on the
length of specific window period but also on the incidence of the infection among
blood donors

43. Assignment 02
 List out the TTI that are screened in Sri Lanka for all the blood donors.
 What are the methods/screening assays used locally to screen these infections?
Email the answers to mkrishnapillai@yahoo.com before 25.01.2021 with,
1. Your name
2. Roll number

44. Questions?

45. Thank you!