Autopsy and Post-Mortem Examination

An autopsy is the systematic examination of a body after death to establish the cause and manner of death, to describe the disease processes present, and to answer clinical, legal and public health questions. It combines external examination, internal dissection of all body cavities, weighing and sampling of organs, and laboratory tests.

Two main types exist. A clinical (hospital) autopsy is done with the consent of the next of kin to explain an illness or death, to audit care, and to teach. A medicolegal (forensic) autopsy is ordered by the legal authority responsible for sudden, unexplained, violent, suspicious or unnatural deaths, and it does not need family consent.

The examination includes external description, evisceration, examination of the brain and the organs, histology, and as needed microbiology, toxicology, biochemistry, genetic tests and imaging. Post-mortem CT or MRI can be used as an addition or, in some settings, as an alternative to dissection.

A full autopsy takes 2 to 4 hours. A preliminary cause of death is given within 1 to 2 days, and the final report, with histology and other tests, takes 4 to 8 weeks.

Autopsy changes the clinical diagnosis in a substantial minority of cases. Major discrepancies between the clinical and the autopsy cause of death occur in about 10 to 25% of hospital deaths, and some of these would have changed treatment had they been known in life.

Indications.

• Sudden, unexpected or unexplained death.
• Deaths where the clinical diagnosis was uncertain or the course unusual, or following a procedure or treatment complication.
• Maternal deaths, stillbirths, neonatal deaths and sudden unexpected death in infancy and childhood.
• Sudden cardiac death in a young person, with the possibility of inherited heart disease in relatives.
• Deaths with a possible public health risk (suspected notifiable infection, poisoning, occupational disease).
• Deaths in custody, after violence, accidents, or in suspicious circumstances (medicolegal).
• Deaths from suspected medical error or complications, and requests from relatives or the coroner.
• Teaching, research, and quality audit, and clarification of the cause of death for insurance or compensation claims.

Not indicated when the cause of death is clear and documented, the family objects, and no legal or public health reason applies.

Contraindications and precautions.

• Consent: for a clinical autopsy, written consent from the legal next of kin, with the scope (full, limited, organ specific) and the retention of tissue agreed. Refusal is respected unless the legal authority orders the examination.
• Infection risk: tuberculosis, HIV, hepatitis B and C, viral haemorrhagic fevers, prion disease and novel respiratory infections need risk assessment and the right facility, protective equipment and technique. Suspected Creutzfeldt-Jakob disease requires special handling and instruments.
• Religious and cultural needs: rapid burial and avoidance of dissection are important for many families, so post-mortem imaging or needle sampling may be offered.
• Chain of custody and identification for medicolegal cases.
• Embalming before autopsy limits toxicology and microbiology, and is delayed until the examination is done.

Preparation and technique.

Identity is confirmed, consent or legal authority is checked, and the clinical record, imaging and laboratory results are reviewed. The body is kept at 2 to 4°C, and examination is done within 24 to 48 hours where possible to limit decomposition.

The external examination records the body, injuries, scars, devices, rigor and lividity, and signs of disease. Photographs and, where needed, X-ray or CT images are taken.

The organs are removed and examined in turn: the heart and great vessels, lungs, liver, spleen, kidneys, gastrointestinal tract, endocrine organs, brain and, when indicated, spinal cord. Organs are weighed and cut, and the findings are described.

Samples are taken for histology (fixed in formalin), culture and molecular tests (taken sterile before organs are handled), toxicology (blood from a peripheral vein, urine, vitreous humour, liver, stomach contents), and genetic testing (blood or tissue frozen for DNA). Tissue and fluids are stored as the law and consent require.

The body is reconstructed and released, and a report is made with a clinicopathological summary.

Normal appearances.

The report lists organ weights and compares them with reference ranges for age, sex and body size, and describes normal anatomy. Post-mortem changes (livor, rigor, autolysis, decomposition, bacterial overgrowth) are described and separated from disease.

Interpretation.

• Cause of death: the disease or injury that began the chain of events that led to death (the underlying cause), and the immediate cause. Contributing conditions are listed.
• Manner of death (medicolegal): natural, accident, suicide, homicide or undetermined, set by the legal authority with the evidence from the scene and circumstances.
• Clinical correlation: the main clinical diagnoses are confirmed, refuted or extended, with major and minor discrepancies. Common missed diagnoses are pulmonary embolism, myocardial infarction, infection, aortic dissection and malignancy.
• Cardiac deaths: coronary thrombosis, cardiomyopathy, myocarditis, valve disease and structural anomalies, with histology. A structurally normal heart in a young person suggests a channelopathy, and blood is kept for genetic testing.
• Infants and children: the full investigation includes the scene, medical and social history, skeletal survey, metabolic and infection tests, and histology. A death that stays unexplained after full investigation is classed as unexplained.
• Neonatal and stillbirth: examination of the placenta, cord and membranes, growth, malformations, infection and chromosomal tests.
• Toxicology: drug and alcohol levels are interpreted with the circumstances, since post-mortem redistribution changes concentrations.
• Negative autopsy: no structural cause found. Further tests (toxicology, genetics, histology review) are done before concluding.

Critical values and findings needing immediate action.

• Findings of a notifiable or highly infectious disease: immediate report to public health authorities and protection of staff and contacts.
• Findings suggesting an inherited condition (cardiomyopathy, channelopathy, aortic disease, metabolic disease): communication with the family and referral for genetic counselling and cascade testing.
• Signs of unlawful death or injury in a clinical autopsy: stop and inform the legal authority.
• Findings that reveal a treatable disease in relatives, or a risk to staff or the public (anthrax, poisoning): urgent communication.
• Unexpected findings that bear on a pending legal or insurance question: reported through the proper channel.

Limitations and artefacts.

• Decomposition, embalming and delay destroy tissue detail and make toxicology, microbiology and histology unreliable.
• Resuscitation injuries (rib fractures, haemorrhage, liver injury) and treatment effects (drains, lines) can be mistaken for injury or disease.
• Post-mortem redistribution of drugs and agonal changes change blood levels, so interpretation depends on site of sampling.
• Many causes of death leave no structural trace (arrhythmia, epilepsy, metabolic disease, some poisoning), and a negative autopsy is common in sudden death.
• Limited autopsies (a single organ or cavity) can miss findings in other sites.
• Consent limits the extent of tissue retained.
• Over interpretation of minor findings, and bias from the clinical history, lead to wrong conclusions.
• Autopsy rates are falling, and skills and facilities have declined, which reduces quality.

Special groups.

• Infants and children: specialist paediatric pathology, with a multi-agency review and support for parents.
• Stillbirth and neonatal death: parents are offered a full, limited or imaging based examination, and placental examination is done whatever is chosen.
• Maternal deaths: audit of the causes (haemorrhage, hypertension, sepsis, embolism) improves care.
• Young adults with sudden cardiac death: full cardiac examination by an expert, retained blood for genetic tests, and family screening.
• Deaths in people with cancer, HIV or on immunosuppression: infection and treatment complications are common.
• Healthcare workers exposed to infectious deaths: safe working and post-exposure plans.
• Regions: autopsy rates are very low, and many deaths occur at home without a certified cause. Verbal autopsy (a structured interview with relatives) and minimally invasive tissue sampling with needle biopsies of the lung, liver and other organs, with blood and cerebrospinal fluid tests, give useful cause-of-death data where full autopsy is not possible. Cultural and religious practices, cost, and few pathologists restrict access.

Follow up tests.

• Histology of organs and any lesions.
• Microbiology: culture, PCR and serology on blood, tissue and fluid.
• Toxicology and biochemistry (vitreous humour for electrolytes and glucose).
• Genetic testing (cardiac, metabolic, chromosomal), with consent.
• Post-mortem imaging (CT, MRI, skeletal survey).
• Neuropathology review of the brain.
• Clinicopathological review meeting with the treating team.
• Family counselling and screening for inherited disease.