Abstract

Rh is one of the most polymorphic and immunogenic blood group system with more than 50 antigens, of which Rh D is the most immunogenic. The red cells giving negative reactions in anti-D test and positive in anti-human globulin phase are considered as weak D. This weak D test isdone by Conventional tube technique. However, Column agglutination technology is considered to be more sensitive than conventional tube technique. This study intends to identify if Column agglutination technology identifies more weak D than conventional tube technique. Methods: This study was conducted in a tertiary care hospital in Hyderabad for a period of six months. The patients who were typed Rh D negative were further tested for weak D by both CAT and CTT with IgM, IgM + IgG anti-D sera and the results were compared. Results: Of the 3132 blood samples tested 153 were Rh D-negative (4.8%) of which 78 (51.4%) were O negative, 48(31.4%) were B negative, 21(13.7%) A negative and 6 (3.9%) AB negative. Among these samples5 were positive for weak D (3.3%), of which 3 were belonging to O and one each belonging to B and AB blood groups. The grade of the reaction for the weak D samples was 2-3+ in AHG phase with IgG alone &IgG + IgM (blend) anti-D in 4 of 5 samples tested by CTT Conclusion: Weak D test by CTT may miss a few weak D when compared to CAT due to lower sensitivity. However further studies regarding this phenomenon and clinical significance for the weak D needs to be evaluated.

Description