This document discusses the importance of blood examination in medicolegal cases and outlines various tests that can be used to analyze blood evidence. It describes how physical properties, screening tests, confirmatory tests, microscopic analysis, and genetic markers can be used to determine if a stain is blood, if it is human blood, and sometimes can help identify whose blood it is. These blood tests are important for criminal investigations, mass disasters, paternity disputes, and clinical diagnostics.

2. قَالُواْ سُبْحَانَكَ لاَ عِلْمَ لَنَا إِلاَّ مَا عَلَّمْتَنَا إِنَّكَ أَنتَ الْعَلِيمُ الْحَكِيمُ البقرة 32

3. By BY Ashraf Mahmoud Emara Professor of Clinical Toxicology Forensic Medicine and Clinical Toxicology Department Faculty of medicine Tanta university

5. Introduction Medico-legal importance of blood examination: How would you prove that a stain is blood? How to prove that the stain is human? Does the blood belong to a certain person?

7. PH of about 7.4. It is mainly composed of: Cells (about 45%) Plasma (about 55%). Introduction

8. Introduction Volume of blood is about 8 to 8.5 % (80-85 ml per kg) of body weight. Types of cells: Red blood cells (RBCs) White blood cells (WBCs). Platelets.

10. Blood of a victim or assailant may be found on: Weapon Clothes Scene of the crime. In criminal cases

11. In mass disasters. In criminal cases

12. In cases of rape, a blood stains may be found on the clothes or the body of the victim. In criminal cases

13. Disputed paternity. Cases of mixed up children in maternity hospitals. In Hereditary problems

14. Incompatible blood transfusion In Clinical problems

16. The physical properties of blood: Fresh blood (oxy Hb and reduced Hb): Red Soluble in water . Old blood (Methaemoglobin): Brown Soluble in diluted acids and alkalies. Very old blood (Haematoporphyrin): Black Soluble in conc. acids and alkalies.

17. Screening tests (Macrochemical tests or oxidase tests): Good negative tests. Done on a filter paper or in a test tube. Depend on presence of peroxidase enzyme Peroxidase present in other body secretions and many vegetables. Name: Benzidine test Phenol-phthalein test (Kastle Meyer’s test) Guaiacum test

18. Screening tests (Macrochemical tests or oxidase tests): Benzidine test

19. Screening tests (Macrochemical tests or oxidase tests): Phenol-phthalein test (Kastle Meyer’s test)

20. Screening tests (Macrochemical tests or oxidase tests): Guaiacum test

21. Confirmatory tests: Microchemical tests: Depends upon the formation of special crystals of haemoglobin derivatives after addition of specific chemicals to the blood. Teichmann test (Haemin crystal test) Takayama test (Haemochromogen crystal test)

22. Microchemical tests: Teichmann test (Haemin crystal test) Small brown regular crystals with rhombic termination of acid hematin.

23. Microchemical tests: Takayama test (Haemochromogen crystal test) Needle salmon pink, feathery shaped crystals of alkaline hematin arranged in clusters or rosettes.

24. Confirmatory tests: Spectroscopic examination: Haemoglobin can give characteristic spectra on adding different reagents so if the stain gives at least 2 of the known spectra, this is a proof that the stain is blood.

25. Confirmatory tests: Microscopical test: Human RBCs: Rounded Biconcave side view Non nucleated.

26. Confirmatory tests: Microscopical test: Non Mammalian: Oval Biconvex Nucleated Camel RBCs: Oval Biconvex Non nucleated.

28. Precipitin test: antigen antibody reaction Stain extract + antisera ring of white precipitate Antiserum is prepared by injection a rabbit with human blood, antibodies will be formed in its serum against human antigen.

29. Gel diffusion electrophoresis Latex particle agglutination test

31. Sexing (intact cell to give accurate results): Female: Davidson body “thin stalked drumstick projection of chromatin” in polymorph nuclear cells.

32. Male: Y chromosome can be seen in cells soaked in solution of Mg Cl 2 and stained with chemical quinacrine hydrochloride.

33. Individuality of blood: ABO system. Wet sample. Dried sample: Absorption inhibition test: Mixed agglutination test: NM (S) system. Rh antigen.

34. Individuality of blood: Other genetic markers: Red cell isoenzymes: Types of Hemoglobin: HbA (adult Hb) HbF (Fetal Hb in fetus and very young infant) HbS (in sickle cell anaemia, present in 8-11% of blacks). HbC (normally present in black people Hb variants are detected by electrophoresis.

35. Individuality of blood: The human leukocyte antigen system : It is used in doubtful paternity and before organ transplantation. DNA printing

36. Thank you