Comparison between conventional tube method and gel card technique for blood crossmatching: A study in a tertiary care center of north India

The cross-matching of blood can be performed by various methods like saline tube method and gel card technique. Saline tube method is most commonly used in blood banks, whereas the latest method used is Gel card technique for cross-matching. Both techniques have their advantages and disadvantages. The main aim of this study was the comparison of gel card and conventional tube test for sensitivity and specificity, time and efficacy. This prospective study was done at the Department of Blood Transfusion, BPS GMC Khanpur Kalan, Sonipat, Haryana. A total of 500 samples collected at the Department of Blood Transfusion, were cross-matched using conventional tube method (spin tube method) with and without using AHG and Gel card Method. 497 (99.4%) samples were compatible, and 3 (0.6%) samples were incompatible with Gel card method, but by test tube method 492 (98.4%) samples were consistent, and 05(1.6%) were false positive (FP). Incompatibility of those 05 samples (FP) disappeared after incubation with AHG reagent at 37°C saline tube method. The sensitivity and specificity of both gel card method and saline tube method with AHG methods is 100% whereas the specificity of saline tube method without AHG is 98.9%. The average time taken by Gel card method was 20-30 minutes for a single compatibility test whereas in conventional spin tube method with the use of AHG (IAT) average time required was 90 minutes and without AHG it was 45-60minutes. The sensitivity and specificity of the spin tube method and the gel card method are comparable to each other. But the gel card method is easy to perform, rapid, reliable procedure and results can be recorded. In contrast, spin saline tube method is more time consuming, and results cannot be preserved. Thus gel card technique can be preferred over the spin tube method.

D ANTIGEN

Background: In 1939 Rh antigen was discovered by Levine and Stetson. Rhsystem antigens are very immunogenic, they can produce significant Hemolytic Disease of thefetus and Newborn as well as hemolytic transfusion reactions. There are numerous variants ofD, the most common subtypes are Weak D and Partial D, now called as abnormal D antigens.The incidence of Rh negativity worldwide varies between 3%-25% and that of weak D antigenranges from 0.2%-1%. Objectives: To find out the frequency of Rh negativity and weak Dantigen among the donors coming to the blood bank of The Children’s Hospital & Institute ofChild Health, Lahore and to review the clinical significance of weak D antigen in transfusionperspective especially its role in alloimmunization caused by Weak D antigen when transfusedto Rh negative individuals. Study Design: Cross- sectional study. Setting: The Children’sHospital and Institute of Child Health, Lahore. Period: 1st Jan 2015 to 31st May, 2015. Materialsand Methods: 6320 healthy donors were randomly selected. All samples were grouped forABO and Rh-D factor by immediate spin tube technique. All samples found Rh negative, werefurther processed for weak D antigen with monoclonal anti D sera by using indirect Coomb’stechnique. The presence of macroscopic or microscopic agglutination was recorded as Rhpositive. In case there was no agglutination the mixture was washed 4 times with normalsaline. After the last wash, saline was decanted and 2 drops of monoclonal, polyvalent antihuman globulin was added. Macroscopic and microscopic agglutination was looked for andany agglutination at this stage was recorded as weak D antigen. Positive control (check cellsi.e. washed O positive cells with diluted anti D) and negative control (washed O positive cells)were always put. Results: Among the 6320 healthy donors, 1224(19.4%) were Rh-D negativeand 5096(80.6%) were Rh-D positive. Of the 1224 Rh D negative samples, 3 (0.2%) samplesfound positive for weak D antigen. Conclusion: The frequency of Rh negative blood groupwas 0.2% among the healthy donors at The Children’s Hospital and ICH, Lahore. Although thefrequency is low but it’s proven by literature that weak D antigen can produce alloimmunizationif transfused to Rh-D negative subjects. At the same time the cases of hemolytic reactionsreported previously with Weak D antigen have been scarce.