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- Lividity: Dark purple coloration (not cyanosis) over dependent areas due to pooling of blood.
- Starts in 20-30 min as dull red patches then deepen in intensity and coalesce to form large areas of reddish-purple discoloration.
- Within 60min blood becomes in-coagulable due to the release of fibrinolysins.
- Clots may persist when the mass of clot is too large.
- Carbon monoxide poisoning or refrigeration soon may cause "cherry red“ or pink (methaemoglobin).
- After about 10-12 hours the lividity becomes "fixed" and repositioning the body, will result in a dual pattern of lividity since the primary distribution will not fade completely.
- The blanching of post mortem lividity by thumb pressure indicates that the lividity is not fully fixed.
- Distribution of lividity reflects the position at death.
- Contact pallor or pressure pallor. A supine corpse will display contact pallor over the shoulderblades, buttocks, calves, heels and location of firm fitting clothing, belts or any firm object lying beneath the body.
- Lividity becomes visible in 1/2 to 4 hours. well developed in next 4 hours and maximum at 8 to 12 hours. *Polson
- In the heart, lividity may be mistaken for an acute MI, in lungs may appear as hemorrhage or pneumonia. Livid coils of intestine may falsely suggest haemorrhagic infarction.
- In the areas of lividity the blood is confined to vessels while in bruising the blood infiltrates the tissues and cannot be readily washed away under running tap water.
Category: Forensic Medicine Notes