Forensic Science International, 16 (1980) 237 - 240 0 Elsevier Sequoia S.A., Lausanne - Printed in the Netherlands

237

THE OBSCURE AUTOPSY *

BERNARD KNIGHT

Department of Pathology, Welsh National School of Medicine, Royal Infirmary, Cardiff (Great Britain)

When clinicians certify the cause of death without the benefit of a full autopsy, they are frequently incorrect in their diagnosis. Several surveys, such as that of Waldron and Vickerstaff [l] , have shown that the error varies between 45 and 55 per cent, with about half this proportion having a con- siderable discrepancy from the cause as shown by a subsequent autopsy.

However, though the autopsy is vastly more accurate in attaining the true cause of death, it is not inevitably successful. Estimates of the propor- tion of autopsies which fail to demonstrate a convincing cause of death vary, but lie in the region of five to ten per cent.

This small but significant proportion of autopsies where the cause of death remains unascertained, occurs most frequently in children and young adults. This in itself suggests that there might be an even greater hidden rate of obscure deaths. The low or almost absent rate of failures in the older age group may be fallacious, due to the almost universal presence of some de- generative lesions such as coronary or cerebral atherosclerosis. These are used as the cause of death, whereas in fact the true cause may be the same occult processes that cannot be detected in the younger persons, who do not have the convenient overlay of degenerative diseases.

The practical problem arises as to the procedure which the pathologist should employ when faced with a disconcerting absence of any convincing morphological cause of death. The discussion here is confined mainly to pre- sumed death from natural causes, where nothing in the clinical background or investigative history suggests that any unnatural event took place. How- ever, the absence of a relevant history by no means excludes an unnatural death, expecially in the case of poisoning.

Some deaths remain obscure, but this is anticipated by the pathologist. The major example is the cot or crib death, the Sudden Death in Infancy Syndrome, being at the present state of medical knowledge without any sig- nificant pathological findings in at least 85 per cent of cases. Faced with this type of death in a young infant, the pathologist expects from the history, season, age, etc., to be confronted with an absence of significant findings. In these cases, the major task of the pathologist is to exclude any other cause of

*Paper presented at the Third Meeting of the International Study Group of Natural Unexpected Death (ISNUD), Copenhagen, Denmark, August 16 - 18, 1979.

death, especially an unnatural cause including the battered child syndrome. In the past, much social distress was caused by pathologists using some un- justified and unsatisfactory explanation for the cause of death, such as “suf- focation”, “aspiration of gastric contents” or some such unnatural term which could not be justified by pathological findings. Many pathologists em- ploy a term indicating a respiratory infection, which is usually not justified by the pathological findings, but which in some cases satisfied the authorities and parents. However, it is more realistic to use the term Sudden Infant Death Syndrome now that the syndrome is widely recognised by both medical and lay persons alike.

The obscure autopsy is most perplexing when the deceased is a young adult. The following case will act as an example upon which to discuss the practical procedure which is suggested for routine use.

A 20-year old young man in apparent perfect health travelled from a nearby town to play rugby football against another club. The game was strenuous but no ill-effects were noticed. That evening the young man drank a number of pints of lager, but not to excess. This was his normal practice each week, though he was by no means an alcoholic. That night he spent at the house of a friend and in the early hours of the morning awoke and began vomiting. Shortly afterwards he collapsed and died.

At autopsy the next day nothing abnormal could be found. There were no injuries, all organs appeared normal. The heart was of normal size, the coronary arteries free from atheroma and all other cardiovas- cular structures were completely normal. Subsequent histology and his- tochemistry of the myocardium showed no abnormality. Toxicological screening of blood and urine revealed nothing except a small quantity of alcohol (11 mg per 100 ml). Bacteriology and virology from the bron- chi and lungs revealed no pathogens. After a protracted and expensive investigation, no cause of death could be offered to the coroner and the case remains in the “unascertainable” file.

The author has seen several other similar cases in young to early middle- aged people where the only common factor was drinking at or shortly before the time of death, though in none of these cases was the intake of alcohol in any way excessive.

The practical problem at autopsy is to develop a routine which will en- sure that no significant findings are missed. After the usual full dissection of the organs has been completed and nothing significant found, the first recom- mended procedure is to reexamine the coronary arteries in much greater detail. Normally, the author cuts across the coronary arteries in a transverse fashion, at intervals of about 4 mm. In the obscure cases, the coronaries are reviewed in minute detail, cuts being made between the original cuts so that no short segment of stenosis is missed. In any suspicious areas, the transverse cuts are then joined by longitudinal section of the vessel using coronary scis- sors. Particular attention is paid to the first few millimetres of the main trunk

239

of the left coronary artery and to the junction of the left circumflex and left anterior descending branches. Also the first part of the left circumflex vessel is inspected closely. The right coronary artery is also reviewed, from the ostium to its termination on the posterior margin of the heart. If necessary, the posterior descending branch is also examined, though this rarely gives much evidence of occlusion.

This review of the coronary system sometimes pays dividends, especial- ly in the middle-age group which at first sight appear to have good coronary vessels. A tiny segment of coronary artery may be occluded over a distance of only two to three millimetres either by pure atheroma, or a subintimal haemorrhage, ruptured plaque or less commonly a localised thrombosis.

Where a second detailed examination of the coronary arteries reveals nothing, the smaller branches of the pulmonary arteries are opened, in case a small pulmonary embolus has been missed at the first examination. This is rarely the case, but on one or two occasions this has been the only abnormal finding.

Re-examination of the cerebral vessels is always carried out, but in cases where the death has been sudden it rarely happens that a cerebral cause of death is found where it was not obvious at the first opening of the skull. Naturally, a ruptured berry aneurysm or other intra-cranial haemorrhage must be obviously visible at first sight, in order to have caused death. All the other organs are then examined again, but in cases of sudden death little is usually found if the cause is not in the heart, great vessels or cranial cavity.

The next step is the taking of samples for toxicology and the usual blood, stomach contents, intestinal contents, urine and liver samples are re- tained and sent to the laboratory. Unfortunately, if there is no known his- tory of the administration of any toxic substance, no assistance can be offered to the laboratory as to the nature of the drugs to be sought. A blind screen- ing test must be carried out which can be very expensive for the tax-payer.

Histological examination is the next step supplemented by histochemi- cal enzyme studies of the myocardium, using dehydrogenase techniques. Where the heart weight is more than 400 grams, the possibility of hyperten- sive heart disease is always considered and the histochemical loss of malate dehydrogenase in the inner half of the left ventricular wall is considered to be diagnostic. Where the coronary arteries appear to be perfect, there is little possibility of an occult infarct being found. A cardiomyopathy is the other major possibility, but the criteria must be strictly observed, as there is a sub- jective tendency to accept an insignificant degree of interstitial cellularity and abnormal myofibril staining as evidence of a diseased muscle. At least six sec- tions of myocardium must be searched, taken from strategic places in the heart wall.

All other organs must be reviewed histologically, though in cases of sud- den unexpected death it is unusual to find any significant abnormality out- side the heart and possibly lung. The possibility of a fulminating virus pneu- monia must be considered, though the naked-eye appearances of the lungs is usually very suggestive.

240

Bacteriology and virology of blood and lung tissue has rarely been help- ful in the author’s experience but are usually performed for the sake of com- pleteness.

When the toxicological results are available, any abnormal substance re- ported must be evaluated in the light of the level obtained, in relation to therapeutic doses and in relation to the length of time that the deceased sur- vived after he could possibly have taken such a drug. Thus even very low levels may be significant if there has been a considerable time for excretion and detoxification to occur. The advice of an experienced toxicologist is in- valuable in deciding whether any positive findings are significant as a cause of death.

When the results of all investigations are available, the case must be re- viewed again and an honest opinion offered as to whether any positive find- ings are sufficient to have caused death. In the author’s experience, these an- cilliary investigations more often provide no help than the occasions on which they give the answer. In other words, if at the end of the actual autopsy no cause of death is apparent then, with the possible exception of a positive toxicological result, most cases will remain obscure and must be reported as such to the investigating authority. However, the absence of injuries, evi- dence of poisoning or well-recognised natural disease is in itself a significant finding in that though we did not discover what the deceased died from, we at least discovered what he did not die from !

There must be complete honesty on the part of the pathologist and a readiness to admit defeat. The younger pathologist, especially, feels embar- rassed when he cannot provide the answer and there is a temptation either to assume some unwarranted cause of death or to attribute significance to insig- nificant findings. As the pathologist increases in experience and maturity, he is more ready to concede that he cannot find the cause of death and this is more satisfactory. There are dangers in exceeding the conclusions which are legi- timately to be extracted. As an example, the author once conducted an autopsy on a small boy found dead in a derelict house. There were no marks of violence and autopsy was completely negative. In the derelict house were some old medicine bottles, including aspirin, and though toxicological exa- mination was negative, there was some persuasion by the authorities for the pathologist to agree that death may have been due to the child sampling the old medicines. As there was noevidence of this, this explanation was rejected which was fortunate, as some months later an older girl strangled another young child and confessed to having strangled the first! Thus in the obscure autopsy, though every effort should be made to discover the truth, truly negative findings should be recorded as such so that the way is left open for future revision if further facts come to light.

References

1 H. A. Waldron and L. Vickerstaff, Intimations of Quality; Antemortem and postmor- tem Diagnosis, London, Nuffield.