Bruises -Types, Causes, Factors, Color Changes and Significance

Extravasation of blood into the tissues due to rupture of capillaries, venules and small arterioles usually as a result of trauma, is called a bruise.

Types of Bruises

Depending on the location, bruises are classified into:

1. Subcutaneous bruises
2. Intradermal bruises
3. Deep bruises or contusions

Causes

1. Blunt trauma is the common cause of bruising, e.g. with stick, stone, stick or fist.
2. Pathological bruising may also occur due to trivial trauma, as in hemophilia and other bleeding disorders.

Bruises often co-exist with abrasions and lacerations. The degree of violence required to produce bruise varies from firm gripping to heavy blows, depending on many other factors.

Factors Affecting Bruising

1.       Tissue type

Loose connective tissue type sites e.g. eye, face, genitalia, show more bruising. Bruises are also more marked in sites overlying bones, but are rarely seen on the scalp, palms or soles.

2.       Severity of Trauma

More severe is the trauma, more bruising occurs

3.       Age

Infants and elderly bruise easily. Infants have loose and delicate skin while elderly have lost elasticity of skin and blood vessels

4.       Sex

Women bruise more easily than me

5.       Skin color

Fair skinned persons have more obvious bruises

6.       Diseases

Blood dyscrasias, hypertension patients bruise more easily.

7.       Gravity Shifting

Fascial planes more prevent blood from torn vessels to reach the surface, thus bruise appears in remote areas. E.g.

• a person having fracture of upper end of humerus may show bruising in elbow
• a person hit on forehead may show bruising over eyes (Spectate hematoma, black eye)
• fall on the vertex –bruise may be behind the ear (Battle’s sign)

Aging of Bruise/Color Changes

These are due to degradation products of blood.

Color	Approximate Time	Cause
Red	Fresh	Hemoglobin
Blue	24 hours	Deoxygenated hemoglobin
Bluish black	2-4 days	Hemosiderin
Greenish	5-7 days	Biliverdin
Yellow	7-10 days	Bilirubin
Disappears	2-4 weeks

Exception is subconjunctival hemorrhage (or bruise, black eye) which follows the following sequence:

Red –>Yellow –> Disappears

Yellow color or yellow tinge in a bruise does not appear before 18 hours. In regions of dense fatty tissue e.g. back, bruise does not appear quickly and is also slow to disappear.

Characteristics of Bruise

• Bruises may not always show at the original impact site due to gravity shifting
• Size of the bruise may not necessarily commensurate with the severity of trauma
• Deep bruises may take 1-2 days to become visible externally, therefore re-examination after 1-2 days is recommended
• Deep bruises may never show up externally (e.g. in vehicular accidents). Deep incisions at autopsy are necessary to demonstrate them.

Forensic Significance

1. Nature of trauma i.e. blunt
2. Indicator of antemortem nature
3. Site of trauma (Gravity shifting must be kept in mind)
4. Degree of violence
5. Identity of weapon
6. Time of injury
7. Purpose of injury
8. Whether homicidal, suicidal or accidental

Conditions Simulating a Bruise

1. In dead –hypostasis
2. In living –irritant skin lesions

Differentiating Bruise from Hypostasis

Hypostasis	Brusie
Due to engorged vessels, extending into dependent epidermal vessles	Due to ruptured vessels, which may or may not be located deep
Situation is on dependent parts only	Can be situated anywhere
Has clearly defined margins which are horizontal	Margins diffusely merge with the surrounding area
There is no swelling and no abrasions	Swelling and abrasions may be present
If a cut is made, blood oozes out which can be washed easily	If a cut is made, blood oozes out which cannot be washed easily
No inflammatory evidence on microscopic examination	Always evidence of inflammation
Uniform color	May be variegated in color
Blood elements are found within blood vessels	Blood vessels are found outside blood vessels