Blood Stains | Medical Science Optional Notes for UPSC PDF Download

Blood Stains

Differential Diagnosis of Red Stain:

• Blood stain
• Rust stains (lacking a dark and glazed appearance, not scaling when heated from the opposite side, and not causing cloth stiffening; soluble in dilute hydrochloric acid)
• Synthetic dye stains (yellowed by nitric acid, with restoration of the original color using a strong alkali solution)
• Mineral stains (comprising iron oxides, red lead, or red sulphide of mercury)
• Vegetable stains (notably from certain fruits like mulberry, gooseberry, currants, and jambans; microscopic examination reveals blood cells. Henna, pan juice, and tobacco, containing tannin, turn black upon the addition of ferric chloride)
• Other stains (such as grease, resin, tar, and pitch, particularly on dark fabrics, resembling aged blood stains)

Blood Stain Analysis

Confirmatory Tests

Take a suspected blood sample and place it on a glass slide. Add a few crystals of sodium chloride and a few drops of glacial acetic acid along the side of the cover slip. Apply heat to form a hematin derivative. The resulting hemin or hematin chloride crystals exhibit a brownish rhombic shape and are arranged either singly or in clusters.

Position a small stain sample beneath a coverslip and permit the Takayama reagent (composed of sodium hydroxide, pyridine, and glucose) to flow under and saturate the sample. Following a brief heating period, observe the crystals under a microscope. Pink, feathery crystals of reduced alkaline hematin (hemochromogen—pyridine ferriprotoporphyrin) arranged in clusters become visible.

Age of Blood stains

• Newly formed stains on light-colored garments exhibit a bright-red hue, gradually transitioning to reddish-brown within 24 hours and eventually turning brown over the course of a few days. With time, these stains may evolve into a black color.
• Fresh stains are initially moist and adhesive; upon drying, they stiffen the fabric due to the presence of proteins.
• Arterial blood, freshly shed, appears bright-red, while venous blood presents as dark-red.
• The determination of age can involve assessing the diffusion of soluble components, such as chlorides, into the surrounding material.
• The fluorescence of a stain diminishes as it ages, attributed to the increasing presence of haematin. It is possible to categorize stains as very fresh, recent, several weeks or months old, or extremely aged.

Antemortem vs postmortem blood stains

• Blood that has leaked during life can desiccate into peelable scales upon drying, attributed to the presence of fibrin. The clot formed in such cases can be lifted in its entirety.
• In contrast, blood that has coursed after death tends to disintegrate into powder as it dries, preventing the clot from being lifted as a whole.

Blood Stains-Repeats 

1. How will you confirm a stain to be of blood and determine its species origin (1996)? 
2. Discuss differential diagnosis of "Red stain" Discuss briefly the various chemical tests for detection of human blood (2002). 
3. Enumerate the various screening tests for blood stains. Describe the tests to establish the blood grojp of the blood stain (2004). 
4. Discuss in detail various examinations done in the laboratory to identify a blood stain (2006).