Compare clinical and medicolegal autopsy. Describe the conduct of a medicolegal autopsy and the preservation of viscera.

Types of Autopsy

Objectives and Preliminaries

• The objectives of a medicolegal autopsy — to establish the identity of the deceased; the time since death; the cause of death; the manner (natural, accidental, suicidal, homicidal); to determine the nature and cause of injuries and whether they were antemortem or postmortem; to collect and preserve evidence; and in the newborn, to determine viability and live birth
• Requisites — a written requisition and the inquest papers; the dead body correctly identified; the deceased's clothing; the hospital records if the death was in hospital; and any weapon or article sent for comparison
• Preliminaries — read the papers and the case notes; note the identity, the identifying constable, the date and time of starting; and photograph the body clothed and unclothed

Conduct of the Autopsy

• External examination — clothing (described, damage matched to wounds, stains noted, then preserved)
• general description
• identifying features
• postmortem changes to estimate the time since death
• injuries described individually by situation, size, shape, margins, direction, depth and age, with measurement from fixed anatomical landmarks and from the heel → Examine the natural orifices, the hands (for defence wounds and grasped material), the nails (scrapings) and the perineum → Head — a coronal (ear-to-ear) incision, reflection of the scalp both ways, examination of the inner surface for bruising that is invisible externally, removal of the skull cap, and examination of the meninges, brain, base of skull and, where indicated, the neck structures after the head and chest have been drained of blood → Body — an I-shaped, Y-shaped or modified Y (V-shaped) incision
• the modified Y is preferred where the neck must be examined and where the body will be viewed, as it can be concealed by clothing → Evisceration — the virchow technique (organs removed and dissected one by one), rokitansky (in situ dissection), letulle (all organs removed en masse as one block, best for preserving relationships) or GHON (removal in three blocks — thoracic, coeliac, urogenital) → Each organ is weighed, described externally and sectioned serially → Collect specimens for histopathology, chemical analysis and other investigations → Restore the body decently, complete the report, and hand over the body and the sealed articles with proper documentation
• Negative autopsy — one in which no cause of death is found even after full examination, histology and toxicology; it accounts for a small percentage, and the common causes are vagal inhibition, laryngeal spasm, epilepsy, anaphylaxis and an undetected poison
• Obscure autopsy — one in which the findings are indefinite or insufficient to explain death, requiring further investigation
• Second autopsy — performed after exhumation or on a request from the family or court; the findings are always inferior to the first, because incisions and evisceration have already altered the body, which is an argument for doing the first one properly

Preservation of Viscera and Exhumation

• Viscera are preserved where poisoning is suspected, in a death that is sudden and unexplained, in suspected criminal abortion, in burns, in death under anaesthesia, and where the cause is not established at autopsy
• Standard viscera for chemical analysis — stomach with its contents; the upper part of the small intestine with contents; about 500 g of liver; one half of each kidney; and 100 mL of blood and urine. In special cases also brain (for volatile and hydrocarbon poisons), lung, bone, hair and nails (for arsenic and heavy metals), long bone and the gravid uterus
• Preservative — saturated saline is the routine preservative for viscera, in a quantity sufficient to cover them by about 2 to 3 cm; rectified spirit is used for some purposes but is never used where alcohol, or a poison soluble in alcohol, is suspected; sodium fluoride (with potassium oxalate) for blood alcohol, since it prevents both fermentation and glycolysis; and NO preservative for carbon monoxide, hydrocyanic acid or phosphorus
• Containers — clean, wide-mouthed glass jars, filled to about two-thirds, labelled with the name, autopsy number, contents and preservative, sealed with the doctor's own seal, and handed over to the police with a sample of the preservative and a specimen of the seal for comparison — all of which establishes the chain OF custody
• Exhumation is the lawful disinterment of a buried body. In India it may be ordered only by a magistrate (not by the police or the family); there is NO time limit in India, unlike some countries; it is done in the presence of the magistrate and police, in daylight, with the grave and coffin identified, and samples OF soil taken from above, below and from the sides of the coffin as controls — because arsenic and other substances occur naturally in soil and could otherwise be mistaken for administered poison
• Indications for exhumation — suspected criminal poisoning or homicide discovered after burial; disputed identity; insurance and inheritance claims; and to establish criminal negligence

Postmortem Artefacts

• The distinguishing principle throughout is the vital reaction — an antemortem injury shows bleeding into tissue, inflammation and, later, healing, while a postmortem one does not. Where this is doubtful, histology of the wound margin may resolve it

Applied Aspects

• Open all three cavities every time; a partial autopsy in a medicolegal case is indefensible and will be exposed under cross-examination
• Conduct the autopsy in daylight where possible; contusions in particular change colour under artificial light and may be missed or wrongly aged
• Describe, do not interpret, in the body of the report; findings and opinion are kept separate, and the opinion should follow from the findings recorded rather than from the police account
• Seal the viscera with your own seal and send a specimen of it; a break in the chain of custody destroys the value of a chemical analysis however accurate the result
• Never use rectified spirit where alcohol may be relevant, and never use formalin for viscera intended for chemical analysis, since it interferes with the detection of several poisons
• Do the first autopsy as though there will never be a second, because in practice a second one recovers far less — and the family who requested it will not be told that the answer was lost the first time
• Take soil control samples at every exhumation — from above, below and beside the coffin; arsenic and other substances occur naturally in soil and would otherwise be attributed to poisoning
• Only a magistrate can order exhumation in India, and there is no time limit; confirm the order exists before attending
• A negative autopsy is a legitimate finding, not a failure, and the common causes — vagal inhibition, epilepsy, anaphylaxis, an undetected poison — should be stated with the report rather than a cause invented
• Describe clothing damage and match it to the wounds; a stab wound without corresponding damage to the garment tells you the person was not wearing it, which may be the decisive fact
• Photograph before dissecting, and again at each stage; photographs answer questions in court that a written description cannot, and cannot be taken retrospectively
• Record the time of starting and finishing; the interval between death, inquest and autopsy is frequently relevant to the estimation of time since death
• Incise every suspected bruise; postmortem lividity washes away on incision while a contusion infiltrates the tissue, and this simple test prevents a common and serious misinterpretation
• Record resuscitation injuries explicitly and attribute them; rib fractures from cardiac massage and oral injuries from intubation are otherwise presented in court as evidence of assault
• Do not release the body until the samples are secured and the seals documented; once the body has gone, an omitted specimen cannot be recovered
• Never use formalin for viscera going for chemical analysis, and never rectified spirit where alcohol may be in question; the wrong preservative can destroy the entire investigation
• Send a specimen of your seal with the viscera, so that the chemical examiner can verify the containers were not opened in transit; this is what the chain of custody actually consists of
• A pugilistic attitude in a burnt body is a heat artefact, not a defensive posture, and stating so prevents an entirely wrong reconstruction of events