In interpreting the age of a bruise by colour changes, one should be very cautiousT)

When bruising is extensive and deeply situated, the colour takes a longer time to appear externally. Towards the end stage of healing process, large histiocytes containing coarse granules of haemoxiderin pigment can be seen microscopically in section of contused area. The site of a bruise may contain crystals of haematoidin for a long period after the injury. It is difficult to estimate the exact age of a bruise with any degree of certainty. Subconjunctival eechymoses do not undergo usual colour changes. They are at first bright red, then yellow before disappearing. In old people, healing of bruise is very slow. A bruise sustained at the time of carbon monoxide poisoning is likely to have a bright-red colour.

Ante-mortem and Post-mortem Bruising : In ante-mortem bruising, there is swelling, damage to epithelium, extravasation, coagulation and infiltration of the tissues with blood and colour changes. These signs are absent in post-mortem bruises. Contusions and abrasions produced immediately before death show a marked decrease in the acidic mucopolysaccharides of the connective tissue ground substance, as demonstrated by Akian Blue or dialyzed iron technique. Acidic mucopolysaccharide is absent in contusions more than an hour old, but reappears in the bruises several days old showing the increase of connective tissue. On microscopic examination, the presence of tissue reaction of a degree beyond a margination and limited emigration of the white cells indicates that the contusion was probably ante-mortem. If the red cells have lost their shape and staining characteristics, i and if iron containing pigment is found either at the \ site of injury or in the regional lymph nodes. probably 12 hours have passed after the injury. It is of some value in distinguishing cerebral haemorrhage occurring due to accident from natural haemorrhage, which could have been occurring for

Table (8-2). Difference between hypostasis and bruise.

Trait Hypostasis Bruise

(

Due to ruptured vessels which may be superficial

or deep.

Occurs at the site of and surrounding the

Injury; may appear anywhere on the body.

Lies under the epidermis in the interstices or still deeper.

Often swollen because of extravasated blood and oedema.

May be abraded.

Merge with surrounding area.

Old bruises are of different colour. Fresh bruises may

appear more intense than the adjacent hypostatic area.

Shows extravasation of blood into the surrounding

tissues which is firmly clotted and cannot be washed by gentle stream of water. Subcutaneous tissues are deep reddish-black.

Little lighter over the area of pressure or support.

I) Cause: Due to distension of vessels with blood in the dennis.

(2) Site: Occurs over extensive area of the most dependent parts.

(3) Situation: Lies in the cutis.

(4) Appearance: No elevation of the involved area.

(5) Epidermis: Not abraded.

(6) Margins: Clearly defined .

(7) Colour; Uniform bluish-purple in colour.

(8) Incision: On incision blood is seen in blood vessels,

which can be easily washed away. Subcutaneous tissues are pale.

(9) Effect of Absent in areas of the body which are even

pressure: under slight pressure.

sometime, and which may have caused the accident. Appreciable bruising does not occur 2 minutes after death due to arrest of circulation, but by using great violence, small bruises can be produced up to 3 hours after death, in areas where the tissues can be forcibly compressed against bone and also in hypostatic area, e.g., the back of the scalp, if the body is dropped on the ground, or on trolleys or post-mortem tables. The margins of post-mortem bruises are usually quite sharply defined, and those of ante-mortem bruises are less sharp or indistinct for the greater part, indicating vital reaction in the damaged tissues. Sometimes, haemorrhages are seen in areas of lividity on the arms or shoulders of fat persons without evidence of trauma on other parts of the body. These haemorrhages are produced by tearing of small veins in the skin when the body is lifted from the scene of death. At autopsy blood drains from blood vessels so that the deep bruises may show up against the white areas as the blood in the contusions will not drain.

In decomposed bodies, especially in the scalp, haemolysis of red cells produces a diffuse discolouration of the soft tissues, due to which it becomes impossible to differentiate between an ante-mortem contusion and an area of postmortem hypostasis. In hypostatic areas blood vessels break down with leakage of red cells into the soft tissue which haemolyse due to decomposition; erythrocytes in. soft, tissue in a contusion also haemolyse, and as such the appearances are similar.

Proof of Bruising : At autopsy, bruises may not be readily detected or they may be obscured by

patches of post-mortem lividity, or by the dark colour of the skin. Contusions of the scalp can be » demonstrated by reflecting the scalp and making incisions into the scalp from the aponeurotic surface. Contusions of the neck can be demonstrated by reflecting the various structures of the neck in layers. Contusions in the subcutaneous tissues may be detected by parallel incisions through the skin. Deep bruises are detected by deep incisions made into the muscles. When in doubt, a portion must be taken for microscopy.

(^Medico-legal Importance : (1) Patterned bruises may connect the victim and the object or weapon, e.g., whip, chain, cane, ligature, vehicle, etc. (2) The age of the injury can be determined by colour changes. (3) The degree of violence may be determined from their size. (4) Character and manner of injury may be known from its distribution^ (a) When the arms are grasped, there may be 3 or 4 bruises on one side and one larger bruise on the opposite side, from the fingers and thumb respectively, indicating the position of the assailant in front of, or behind the victim, (b) Bruising of the arm may be a sign of restraining a person, (c) Bruising of the shoulder blades indicate firm pressure on the body against the ground or other resisting surface, (d) In manual strangulation, the position and number of bruises and nail marks may give an indication of the method of attack or the position of the assailant, (e) Bruising of thigh especially inner aspect, and of genitalia indicates rape. (5) In the case of fall, sand, dust, gravel or mud may be found on the body.

Table (8-3). Difference between true bruise and artificial bruise.

	Trait	Artificial bruise	True bruise
(1)	Cause:	Juice of marking nut, calotropis or	Trauma.
		plumbago rosea.
(2)	Site :	Exposed accessible parts.	Anywhere.
(3)	Colour:	Dark-brown.	Typical colour changes.
(4)	Shape:	Irregular.	Usually round.
(5)	Margins:	Well-defined and regular, covered with	Not well-defined, diffuse and irregular;
		small vesicles.	no vesicles.
(6)	Redness and	Seen in the surrounding skin.	Seen in the site.
	inflammation:
(7)	Contents:	Acrid serum.	Extravasated blood
(8)	Itching:	Present.	Absent.
(9)	Vesicles:	May be found «n fingertips and on other	Absent,
		parts of the body due to scratching.
(10)	Chemical tests:	Positive for the chemical.	Negative.

Bruises are of less value, than abrasions because: (1) Their siz.e may not correspond to the size of the weapon. (2) They may become visible several hours or even one to two days after the injury. (3) They may appear away from the actual site of injury, (4) They do not indicate the direction in which the force was applied.J>

(^Complications: (1) A contusion may contain 20 to 30 ml. of blood or even more. Multiple contusions can cause death from shock and internal haemorrhage. (2) Gangrene and death of tissue can result. (3) The pooled blood can serve as a good site for bacterial growth, especially by clostridial group. (4) Rarely, in severe sudden compression of the subcutaneous tissue, pulmonary fat embolism may occur. (

Artificial Bruises : Some irritant substances, when applied to skin produce injuries, which simulate bruises (Table 8-3). They are produced to make a false charge of assault.

I Circumstances of Injuries : Accidental bruises are very common and may be seen on prominences, such as the forehead, nose, elbows and knees. Presence of mud, sand, grease or oil gives an idea of the manner of causation. Multiple contusions from minor trauma are often seen in alcoholics, which may be mistaken to be caused by physical violence. Self-inflicted bruises are rare, as they are painful. They are seen over accessible areas, usually on the head, especially in a hysterical individual or the insane. Homicidal bruises may be seen on any part of the body.