SN4 SHORT NOTE 5M ★ High-yield

Describe the immediate and delayed causes of death from wounds.

Forensic Medicine · 2nd Professional — Para-Clinical

Immediate Causes

Cause	Mechanism and features
Haemorrhage — the commonest	Loss of about one-third of the blood volume (1.5 to 2 litres in an adult) rapidly is usually fatal; slower loss is tolerated better. May be external, or concealed internal — into the chest, abdomen, retroperitoneum, pelvis or thigh, where litres may be lost with NO external sign. Findings: pallor of the skin and organs, poorly developed or absent lividity, an empty contracted heart and great vessels, and pale kidneys with a congested medulla
Shock	Primary (neurogenic) shock — instantaneous death from vagal inhibition, severe pain or fright, with a negative autopsy; and secondary (hypovolaemic or septic) shock, developing over hours with a recognisable clinical course
Injury to a vital organ	Brain and brain stem; heart and great vessels; and injuries incompatible with life such as decapitation or crushing of the head. Death is instantaneous and no other explanation is needed
Asphyxia (mechanical)	Obstruction of the airway; aspiration OF blood, classically after facial and neck injury, and easily overlooked; tension pneumothorax; flail chest; and injury to the cervical cord above C4
Air embolism	Air drawn into open veins under negative pressure — wounds of the neck and great veins, criminal abortion, neurosurgery in the sitting position, and childbirth. About 100 mL is rapidly fatal. Demonstrated at autopsy by the underwater (Ackerman) test, opening the heart under water to look for escaping bubbles — and the chest must be opened carefully to avoid producing artefactual air
Fat and other embolism	See below

CLINICAL PEARL

Concealed internal haemorrhage kills patients who look uninjured. A ruptured spleen, a torn liver, a retroperitoneal bleed from a pelvic fracture or a closed femoral fracture can each hold a litre or more with no external bruise at all, particularly where the blow fell on the lax abdominal wall or the back. Pallor with absent lividity at autopsy, or an unexplained falling blood pressure in the living, is the finding — not the appearance of the skin.

Delayed Causes

Cause	Typical interval and features
Infection	The commonest delayed cause — wound sepsis, septicaemia, peritonitis, meningitis after skull fracture, bronchopneumonia in the bedbound, gas gangrene (Clostridium perfringens, from soil-contaminated wounds), and tetanus, which remains important in India after trivial wounds and has an incubation of 4 to 21 days
Fat embolism	1 to 3 days after fracture of a long bone (especially the femur) or extensive soft-tissue injury or burns. Presents with dyspnoea, confusion and a petechial rash on the chest, axillae and conjunctivae. Demonstrated by fat globules in the pulmonary vessels on frozen section with OSMIC acid or SUDAN stains — which requires frozen sections, since routine processing dissolves the fat away
Pulmonary thromboembolism	1 to 3 weeks after injury or surgery, from deep vein thrombosis in an immobilised limb. A thrombus is distinguished from a postmortem clot by being firm, dry, granular, laminated (lines of Zahn) and adherent to the wall; a postmortem clot is soft, shiny, rubbery, "chicken fat and redcurrant jelly", and not adherent
Acute renal failure	From crush syndrome — myoglobin released from crushed muscle, with hyperkalaemia and acidosis; from prolonged hypotension; or from sepsis
ARDS and multi-organ failure	Days after major trauma, transfusion or sepsis
Complications of treatment	Anaesthetic and surgical complications, transfusion reaction, drug reaction — which do not break the chain of causation unless grossly negligent and independent
Late sequelae	Post-traumatic epilepsy; chronic subdural haematoma presenting weeks after a trivial head injury in the elderly or alcoholic; and suicide following disfigurement or disability

Legal Position and Applied Aspects

The assailant remains liable where the injury was the proximate cause, however long the interval, and this holds even where the victim had a pre-existing condition that made them unusually vulnerable, or where the treatment was imperfect. The law takes the victim as it finds them — the "eggshell skull" rule
Only a genuinely independent intervening cause breaks the chain; ordinary complications of the injury and its treatment do not
Explanation 2 to BNS 100 (formerly IPC 299) makes this explicit — where death is caused by a bodily injury, the person who caused the injury is deemed to have caused the death although proper treatment might have saved the victim
Take frozen sections with a fat stain where fat embolism is suspected; routine paraffin processing dissolves the fat and the diagnosis is lost permanently
Open the heart under water where air embolism is possible, before anything else is disturbed, and open the chest with care to avoid introducing air artefactually
Distinguish thrombus from postmortem clot by adherence and lamination; reporting a postmortem clot as an embolus invents a cause of death
Look for concealed haemorrhage in every trauma death — the chest, abdomen, retroperitoneum, pelvis and thighs — and measure the volume in each cavity rather than describing it
Consider tetanus and gas gangrene in a delayed death after a contaminated wound in India; both are preventable, and their occurrence raises a separate question of the adequacy of the initial treatment

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