Specific features of particular poisons are best considered under the individual headings. It must be emphasized that with the possible exception of corrosive poisons, the autopsy findings are rarely conclusive. The major functions of the autopsy are to exclude other obvious causes of death, and to collect the appropriate samples for toxicological analysis.
Careful examination of the oropharynx and upper airway is vital. Ingestion of corrosives can cause considerable damage to the mouth, pharynx and oesophagus. Inhalation of irritant gases can cause marked congestion and oedema of the larynx and trachea. Internal findings will vary depending on the nature and circumstances of the poisoning in each case.
Acute pulmonary oedema is a common finding in many types of poisoning but is often quite marked when irritant gaseous poisons are inhaled. Some poisons cause fatty change of the liver and may even cause fulminant hepatic necrosis. Acute renal tubular necrosis is sometimes noted, and cerebral oedema may at times be a prominent feature.
It would be wise to exclude poisoning in cases where the cause of death cannot be determined after a thorough postmortem examination i.e. neither natural disease nor injury can account for death; and also in cases of decomposed bodies in which pathological changes are obscured by autolysis.
Classically, glass containers are used for submitting samples for toxicological examination. Nowadays, however, plastic containers tend to be more common than glass and have the advantage that they do not shatter if dropped. Some analyses are affected by the plasticizer in the container and/or cap, and one is advised to consult with the relevant lab about the appropriateness of containers and the types of samples to be submitted prior to submission.
At autopsy in a suspected case of poisoning samples to be sent for toxicological analysis include:
Blood, 30 - 50 ml. This is best taken from a peripheral vein, e.g. the femoral, before starting the autopsy. The heart or great central vessels is the next resort, but these are best avoided if estimation of alcohol or other diffusible substances is required as contamination due to passive diffusion from stomach contents is a possibility. Obtaining blood from body cavities is to be discouraged due to contamination from other body substances.
Urine, 100 - 200 ml via needle aspiration of the bladder.
The stomach is removed between double ligatures, opened (some experts say along the lesser curvature) and the contents and mucosal appearance noted. The stomach contents should be carefully collected in a clean glass jar and sent to the toxicology laboratory. Some laboratories also want the entire stomach to be submitted as well (so that trace substances may be removed from the mucosa).
Generous portions of viscera, at least 50 to 100 g (though some sources recommended that much more be submitted, e.g. Liver (500 g), preferably with gallbladder (or with extracted bile); Brain (500 g); Kidney (a half of each); Spleen (a half); Lung (one), if gaseous poison is involved (remember to tie off the main-stem bronchus to retard loss of the poison by diffusion).
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