Virtopsy (Virtual Autopsy)

Techniques used

• 3-dimensional surface scanning and photogrammetry
• Multislice computed tomography (MSCT)
• Magnetic resonance imaging (MRI)
• Digital image reconstruction, storage and transmission

Advantages

1. Non-invasive: no incision, dissection or mutilation of the body.
2. Wounds and body structure can be studied without disturbing their original relation.
3. Findings are digitally stored permanently and can be reviewed by other experts.
4. Images can be displayed in court as objective visual evidence.
5. Faster than conventional autopsy in many cases.
6. More acceptable to relatives and in communities with religious objections to dissection.
7. Particularly useful for fractures, firearm injuries, foreign bodies and trauma reconstruction.

Disadvantages / limitations

1. Expensive equipment and specially trained personnel are required.
2. Metal objects may produce imaging artefacts.
3. Small soft-tissue injuries and many pathological conditions may be missed.
4. Colour changes of internal organs cannot be assessed properly.
5. Infection status and microscopic pathology cannot be reliably determined without sampling.
6. It may be difficult to differentiate antemortem from postmortem injuries and changes.
7. Therefore, virtopsy is usually an adjunct and not a complete replacement for conventional medicolegal autopsy.

Obscure Autopsy and Negative Autopsy

1. Negative autopsy

• Complete external and internal examination
• Histopathological examination
• Toxicological analysis
• Other necessary laboratory investigations

• Inadequate history, for example vagal inhibition, epilepsy, anaphylaxis or laryngospasm in drowning
• Missed external signs, for example needle marks, snake/insect bite mark, electrical burn
• Incomplete internal examination, such as missed air embolism or pneumothorax
• Inadequate histopathology or laboratory investigations
• Toxicology not done
• Lack of skill or experience of the autopsy surgeon

2. Obscure autopsy

1. Natural disease / functional deaths
   • Epilepsy
   • Cardiac arrhythmia or paroxysmal fibrillation
   • Death precipitated by emotion or exertion
2. Biochemical disturbances
   • Uraemia
   • Diabetes and hypoglycaemia
   • Potassium imbalance, especially hyperkalaemia
   • Anaemic anoxia
3. Endocrine disorders
   • Adrenal insufficiency
   • Thyrotoxicosis
   • Myxoedema
4. Concealed trauma
   • Cerebral concussion
   • Blunt injury to heart
   • Reflex vagal inhibition
   • Self-reduced neck injury
5. Poisoning without gross changes
   • Narcotic poisoning
   • Anaesthetic overdose
   • Neurotoxic/cytotoxic poisons
   • Plant poisons
6. Miscellaneous
   • Anaphylaxis
   • Drug idiosyncrasy
   • Snake bite

Difference

• Negative autopsy: No cause is found after a complete autopsy plus all ancillary tests.
• Obscure autopsy: Minor or doubtful findings may be present, but they do not establish a definite cause of death.

Sample Collection and Preservation of Viscera for Chemical Analysis

Indications

• Poisoning is suspected
• Cause of death is uncertain
• Requested by investigating officer
• Death is sudden, suspicious or unexplained

Routine samples collected

1. Stomach with all contents, including vomitus or gastric lavage if available.
2. Small intestine: about 30 cm of upper intestine with contents, separately tied.
3. Liver: about 500 g, preferably with gall bladder.
4. Kidneys: half of each kidney.
5. Blood: preferably peripheral blood, collected separately.
6. Urine: whenever available.
7. Other useful samples: bile, vitreous humour, hair, nail, suspected food, medicine, containers, or injection-site skin.

Method of preservation

• Keep stomach and intestine in one clean, wide-mouthed glass jar.
• Keep liver, kidney and spleen in another jar.
• Keep blood and urine separately in properly stoppered bottles.
• Do not contaminate solid organs with gastric or intestinal contents.
• The bottle should be filled only up to two-thirds, leaving space for decomposition gases.
• Quantity of preservative should be approximately equal to the bulk of viscera.

Preservatives

• Saturated solution of common salt (sodium chloride) is commonly used.
• Rectified spirit may be used in suitable cases.
• Rectified spirit must not be used in suspected poisoning by:
  • Alcohol
  • Acetic acid
  • Phenol/carbolic acid
  • Phosphorus
  • Paraldehyde
    In these cases, use saturated sodium chloride solution.
• Formalin should not be used for viscera meant for chemical analysis because it interferes with extraction and detection of poisons.
• Blood and urine should be sent in separate sealed containers, preferably refrigerated if there is delay.

Containers, sealing and dispatch

• Use clean, dry, wide-mouthed glass containers with glass stoppers or secure screw caps.
• Avoid rubber inserts because they may absorb or interfere with poisons such as chloroform and phenols.
• Each container must be properly sealed and labelled with:
  • Name of deceased
  • Age/sex, if available
  • Postmortem number
  • Date and place of autopsy
  • Police station/case details
  • Contents of container and preservative used
• Send a separate sample of preservative and specimen seal to the laboratory.
• Send the postmortem report, forwarding letter and relevant history.
• Maintain proper chain of custody and hand over sealed samples to police/investigating officer for dispatch to FSL.

Special samples in selected poisonings

• Lungs: gaseous poisoning, alcohol or chloroform poisoning.
• Brain and spinal cord: strychnine poisoning; brain may also be useful in organophosphorus poisoning.
• Heart: strychnine poisoning.
• Skin with subcutaneous tissue from injection site: suspected injectable drug/poison, drug abuse and snakebite. A control sample from an uninvolved site should also be sent.