RESUMO
Background: Blood is considered to be the most common trace evidence obtained from the scene of crime. Blood grouping reveals vital information regarding identification, in relation to crime investigation. With this respect contamination with dust, rust, bacteria and detergent will have any effect on blood grouping was studied. Material and methods: Randomly A, B, AB, Rh positive samples were taken in duplicates and were added with rusted pins, dust particles, detergent, staphylocopcci bacteria and without any addition one tube was kept in room temperature. Controls were kept in refrigerator at 4-8 ˚C to compare the results. Results: There were lots of changes in blood groups after 10 days of incubation in all tubes with contamination. Blood samples in dust after 10 days incubation had changed from A, B, AB to O blood group with Rh negativity. Blood samples in rust had retained with original ABO group but Rh positives were converted to Rh negative. Detergent tubes had also changed Rh positive to negetive retaining original ABO. There was no change in either ABO or Rh blood groups in tubes with Staphylococci bacteria. Conclusion: Stains contaminated with common agents like dust, rust, bacteria and detergent give inconclusive results by mixed agglutination method with passage of time. The results may be accepted with caution, as the opinion might be medico legally significant.
RESUMO
Introduction: Nucleic acid testing (NAT) is the latest approved method for detection of transfusion transmitted infections. With higher prevalence of infections in window period and occult infections, blood safety can be compromised when testing is done using only serological techniques. With this background this study had been taken up to compare the results of serological test with NAT. Material and methods: Voluntary blood donations were screened for hepatitis B, hepatitis C and human immunodeficiency virus using ELISA. All samples were sent for ID-NAT and results of both methods were compared, analyzed individually. Results: A total of 11,393 blood units were collected during the study period. ELISA test results. showed 176 (1.54%) positivity for these transfusion transmitted infections (TTIs) in total. Among them, 133 (75.56%) was HBV, 22 (12.5%) was HCV and 21 (11.93%) was HIV as shown by ELISA. ID- NAT test results showed 174 (1.52%) positive in total. As analyzed by individual test results, 37 (0.32%) of total blood samples showed positivity in NAT which showed negative results in ELISA. Also 38 (0.33%) of total blood samples (HBV = 27, HCV = 08, HIV = 03) which showed positivity in ELISA were negative in NAT. Conclusion: ID-NAT is definitely a useful screening method for HBV, HCV, HIV. It clarifies infections in window period, occult infections and false seroreactive cases.