SN7 SHORT NOTE 5M

Distinguish autolysis from putrefaction. Describe the postmortem changes in the eye and the certain signs of death.

Forensic Medicine · 2nd Professional — Para-Clinical

Autolysis, Putrefaction and the Distinction

Feature	Autolysis	Putrefaction
Agent	The body's own enzymes, released from lysosomes	Bacteria, chiefly from the large intestine
Requires bacteria?	NO — it is sterile	Yes
Organs affected first	Those richest in enzymes — pancreas, gastric mucosa, adrenal medulla, brain	Begins in the gut and spreads along the vessels; first visible over the right iliac fossa
Gas formation	None	Present — bloating and crepitus
Odour	Absent	Characteristic and offensive
Occurs in a sterile fetus in utero?	Yes — this is maceration	NO
Effect of cold	Retarded but not abolished	Arrested below 0°C

Both begin at death and proceed together in the ordinary case; the distinction becomes visible only where one is prevented — as in the sterile intrauterine environment, where autolysis alone produces maceration

Postmortem Changes in the Eye

The eye changes early and predictably, and is one of the more useful regions in the first hours:
Loss of the corneal and light reflexes — immediate
Segmentation of the retinal vessels ("cattle-trucking") — within minutes; the earliest reliable sign
Fall in intraocular pressure — the eyeball becomes soft and flaccid within minutes; the tension falls to zero by about 2 hours
Tache noire — a yellowish then brownish-black band of drying across the exposed sclera, appearing in 3 to 4 hours where the eyes remain open, and often mistaken for a bruise or a subconjunctival haemorrhage
Corneal haziness from about 2 hours if the eyes are open, or 6 to 12 hours if closed, becoming opaque by about 12 hours
Vitreous potassium rises steadily after death as potassium leaks from the retina, giving a chemical estimate of the interval up to about 100 hours; the vitreous is anatomically protected and resists putrefaction, which is why it remains analysable when blood does not
The vitreous is also valuable for toxicology and biochemistry — alcohol (it lags behind and then exceeds blood, which helps establish the phase of absorption), glucose (unreliable, as it falls rapidly), urea and creatinine (which remain stable and can diagnose uraemia after death), and electrolytes

CLINICAL PEARL

Vitreous humour is the most useful fluid at a decomposed autopsy, and it is routinely not taken. It is anatomically sequestered, so it resists putrefaction long after blood has become useless; it gives urea and creatinine that are still diagnostic, a potassium-based estimate of the postmortem interval, and clean toxicology. Aspirating a few millilitres takes seconds and can be done in every case — and it is the one specimen that cannot be obtained later.

Presumptive and Certain Signs of Death

Grade	Signs
Presumptive (immediate) signs	Cessation of circulation and respiration; loss of consciousness and of all reflexes; primary flaccidity; pallor; and the eye changes. These are not conclusive on their own, because suspended animation may reproduce every one of them
Certain (conclusive) signs	The postmortem changes — hypostasis, rigor mortis, ALGOR mortis and decomposition. These occur only after death and confirm it beyond doubt

The practical rule follows directly — where suspended animation is conceivable, or where there is any doubt, wait for a certain sign before certifying; and where the situation is urgent, continue resuscitation rather than certify on presumptive signs alone
Cremation in India frequently follows within hours, so the margin for error is far smaller than in countries where burial is delayed for days, and this is a genuine practical reason for care rather than a textbook anxiety

Applied Aspects

Take vitreous humour in every autopsy where the interval is uncertain or the body is decomposed; it is quick, it is often the only usable fluid, and it cannot be obtained once the body is released
Aspirate from both eyes separately, slowly, from the lateral aspect, and replace the volume with saline to preserve the appearance of the eye for the family
Do not mistake tache noire for a bruise; it is a drying artefact of the exposed sclera, appears within hours in any body with the eyes open, and has no vital reaction
Distinguish presumptive from certain signs when certifying; the presumptive signs are what a clinician uses at the bedside, and the certain signs are what settle the matter when there is any doubt
Remember that autolysis needs no bacteria; this is why a fetus retained in an intact uterus macerates rather than putrefies, and the distinction excludes infanticide
Vitreous urea and creatinine remain diagnostic after death, which allows uraemia to be established at autopsy when blood chemistry has become meaningless — a genuinely useful piece of postmortem biochemistry

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