1. ABO Discrepancies: A common challenge faced by Blood Transfusion staff Pruthvi Raj, Manish Raturi, Shamee Shastry, Poornima Baliga B. DEPARTMENT OF IMMUNOHEMATOLOGY AND BLOOD TRANSFUSION Kasturba Medical College, MANIPAL, MANIPAL UNIVERSITY
Category code: HS
BACKGROUND :
ABO discrepancies occur when unexpected reactions occur in the forward and reverse grouping. ABO discrepancies can usually be resolved by repeating the test on the same sample by using a saline suspension .
If the discrepancy persists and appears to be due to an error in specimen collection or identification, a new sample should be drawn.
Once encountered, results must be recorded, but interpretation of the ABO type must be witheld until the discrepancy is resolved.
The risk of immunohaemolytic reaction owing to ABO-mismatched mistransfusion is 100 to 1000 times higher than the infection risk.
Figure 2.An example of type 2 Discrepancy
Figure 4.Techniques used for Resolution
ABO discrepancy
Wash RBCs with saline
Discrepancy resolved
Discrepancy further work up
Suspected clerical error(WBIT)
Request for a new sample
AIM :
To observe the frequency of causes concerned with ABO/D discrepancies and assess their resolution.
METHODS :
In our blood bank, blood grouping is routinely performed on Column agglutination technique automated platform ( fig 1&2- Autovue, Ortho clinical diagnostics Ltd ). Resolution of ABO/D discrepancy is done as per the departmental standard operating procedures.(fig.3).
If the initial test was performed using RBCs suspended in serum or plasma , repeat testing of the same sample using saline suspension of RBCs was done to resolve the ABO/D discrepancy. Any technical factors that may have given rise to the ABO/D discrepancy were reviewed and corrected
The techniques used for the purpose of resolution were repeating the sample, saline wash, Conventional tube technique, cold incubation , incubation at 37 degrees, salivary testing, lectins , Adsorption and elution and Antibody screening. (fig.4)
Figure 5.Distribution of types of discrepancies
Cold enhancement
Adsorption and Elution
CONCLUSION :
Incubation at room temperature
Saline Wash
Due to the sensitive technology for blood grouping we could detect all the discrepancies with existing knowledge of different causes for which stringent vigilance has been an added advantage. Hence this is within the scope of various laboratories throughout our country.
The adoption of sensitive technology for blood grouping may increase the frequency of ABO/D discrepancy. However detection opens the doors for further resolution .
Incubation at 37 C
Lectin Study
Repeat Sample
Salivary wash
Antibody Screening
Figure 3.Stepwise approach to resolve discrepancy.
RESULTS :
In the study period of 3 years(August 2012 to June 2015) there were 111 blood group discrepancies(fig.5) out of total of blood groupings with a frequency of 0.11%.Out of all the causes Irregular antibodies were found to be the most common (45.9%). ABO discrepancies were classified based on the cause.
GROUP 1- Weakly reactive or missing antibodies
30.63% (n= 34)
GROUP 2-Weakly reactive or missing antigens
18.91% (n=21)
GROUP 3-Plasma or protein abnormalities
2.73% (n= 3)
GROUP4-Miscellaneous /Irregular antibodies
45.94% (n= 51)
The percentage resolution was 100%.
REFERENCES :
(i)DENISE M. HARMENING Modern Blood Banking and Transfusion Practices.5th edition, University of Maryland, Maryland.
(ii)Layla Bashawri Analysis of ABO Discrepancies Occurring at a University Hospital, Al-khobar, Saudi Arabia. Bahrain Medical Bulletin, Vol. 31, No. 4, December 2009.
(iii)J. Chiaroni, D. Legrand, I. Dettori, and V. Ferrera Analysis of ABO discrepancies occurring in 35 French hospitals. TRANSFUSION Volume 44, June 2004.
(iv)Geoff Daniels Human Blood Groups. 3rd edition. John Wiley & Sons, Ltd., Publication
Figure 1. Equipment used for Automate Blood Grouping