Contusion/Bruise-Factors and Color changes

• The laxity of tissues – 
  • Lax scrotal tissues allow more extravasation of blood
  • Restrictive fascial planes prevent the accumulation of extravasated blood. 
  • The Turkish torture method ‘falaka’ relies on this principle – the soles of the feet are targets of a beating with sticks, causing severe pain but little outward sign of any injury 
• The location of the bruise 
  • Highly vascular areas will be more heavily bruised, and tissues overlying bony support will bruise more readily than the unsupported and resilient tissues of the abdomen
• Age – 
  • Take longer to resolve in the elderly who tend to have more fragile vessels 
  •  Children have a comparatively smaller volume of ‘supporting tissue’;
• The person’s skin pigmentation –
  • Easily recognised in those with pigmented skin.
• The force of impact – 
  • The amount of force used may determine the extent of bruising, as well as the characteristics 
  •  The extent of bruising is also inversely proportional to the sharpness of the object causing it – bruises represent blunt force trauma;
• The existence of co-morbidities –
  • Some people have the tendency to bruise more easily than others, particularly those with bleeding diatheses, chronic alcoholism and liver failure, scurvy and hypertension. I
• The use of drugs – 
  • particularly anticoagulants such as warfarin and steroids;
• Any delay in presentation –
  •  bruises ‘migrate’ along anatomical fascial planes, and may appear some time after the injurious assault; and
• The effects of treatment –
  •  for example the timely application of ice-packs etc

 Colour changes in the contusion

• Colour changes in the contusion is due to disintegration and haemolysis of red blood cells.

1. At first : Red (oxyhemoglobin)
2. Few hours to 3 days : blue (reduced hemoglobin)
3. 4th day : Bluish-black to brown (haemosiderin)
4. 5-6 days : Greenish (haematodin)
5. 7-12 days : Yellow (Bilirubin)
6. 2 weeks : Normal (absorption of pigment)

• Pigments are removed by phagocytes.

Healing process depends on:

• Size and situation of contusion.
• Age and physique of the person
• Presence and absence of disease.

Antemortem contusion

• Sharp,well defined margins.
• Swelling of the tissues.
• Discoloration of the skin.
• Extravasation of blood into the true skin and subcutaneous tissue.
• Doubtful cases-Microscopic examination.

Postmortem contusion

• Can be produced with in 1-2 hrs after death.
• If body is decomposed it is difficult to differentiate between antemortem and postmortem contusions.

Self inflicted contusion

• Rare-can be inflicted by irritant substances like Marking nut(Latin name: Semecarpus anacardium),root of plumbago zeyloxica or rosea.
• Can be differentiated by chemical analysis.

Homicidal contusion

• Shape and size of contusion,indicates the weapon used.

Accidental contusion

• Their position,arrangement,circumstances and surroundings.