Complete Postmortem Techniques Guide - NEET PG FMT

Postmortem techniques are an incredibly important part of the Forensic Medicine and Toxicology syllabus. In this blog post you will learn everything you need to know about postmortem techniques including the must-know topics and their most important points. 

To aid your NEET  PG/NExT exam preparation of FMT, we have covered the topic in a very crisp and concise manner in this blog. Read it till the end and bookmark for future reference.

Let’s begin. 

• Postmortem is also known as
  • Autopsy
  • Necropsy
  • Thanatopsy
  • Postmortem examination (PME).
• Necropsy is the study of a dead body.
• Necro means Dead body.
• Study of death is known as Thanatology.
• Procedures involved in thanatology are known as Thanatopsy.

History

• The 1st autopsy was conducted in 1302, by Varignana in Italy.
• The 1st medico-legal autopsy in India was conducted by Buckley on the body of Mr.Wheeler in Chennai. 

Q. What is the case of the 1st medico-legal autopsy in India?

Ans: Arsenic poisoning.

Autopsy Types

Important Information  In Court of Law or Legal Procedures we have 2 types, Police & Magistrate inquest.

A. Medicolegal Autopsy

• It is on the inquest of either police/magistrate.
• 174 PRC for police inquest.
• 176 PRC for magistrate inquest.
• This autopsy is chosen for unnatural deaths.
• Relative consent is not required.
• It is for law purposes.
• It is done for the whole body.
• It is done to know the cause of death, time since death, and manner of death.
• Most common type in India due to the higher number of unnatural deaths.
• The dead body is returned to the investigating officer.
• It is done by a Forensic expert, RMP (Registered Medical Practitioner).

B. Pathological/Clinical Autopsy

• Relative consent is mandatory.
• It is mostly done in natural deaths.
• It is for a specific body cavity autopsy. Ex: Death due to MI is examined for the heart.
• The dead body is returned to the relative.
• It is for academic purposes or to improve knowledge.
• It is done by RMP (Registered Medical Practitioner).

C. Psychological Autopsy

• A person committed suicide is first done with a psychological autopsy.
• It is not a PME, it is an interview with family members of the dead person.
• It is performed to know the mental status of the person before suicide.
• The interview is done with family members, friends, relatives, and social media.

D. Virtual Autopsy

• It is a visual imaging technique performed in developed countries.
• CT scan and MRI is performed for knowing the cause of death.
• It is also known as virtopsy.

E. Negative Autopsy

• It is performed if there is no identification of the cause of death, after performing PME, lab investigations, and histopathological & toxicological studies.
• Prevalence of negative autopsies is 2-5%.
• It may sometimes occur due to a lack of experience or skill.
• In cases like vagal inhibition, laryngospasm, and epilepsy there is a chance of a negative autopsy.
• Negative autopsy is a completely negative finding.

F. Obscure Autopsy

• In this autopsy we can obtain minimal or inconclusive findings, which is insufficient to give a conclusion.
• Additional investigations like lab investigations, histopathological & toxicological studies are used to conclude the cause of death.
• Obscure autopsy is a minimal gross finding.

Postmortem Techniques 

A. Virchow’s Method (MC)

• Very common method.
• One-by-one organ removal.
• Fast and easy method.

B. Ghon’s/ en-Block Method (G-B)

• Targeted block (C/T/A/P) is taken out.
• Cervical, thoracic, abdominal, pelvic blocks are taken out based on the requirement.
• Thoracic block is taken out in thoracic problems.
• Pelvic block is taken out in sexual assaults.
• Inter-organ relations are intact.

C. Lettule’s/ en-Masses/ Evisceration

• Large masses (C+T+A+P) are taken out.
• Complete viscera is taken out (Evisceration).
• Blood vessels and vascular supply are intact.
• It is for minor bleeding.

Q. Which method is used for simple bleeding?

Ans: Lettule’s/en- masses/Evisceration.

D. Rokitansky/ In-situ Method

• It is an inside dissection.
• It is done in infectious diseases (HIV, Hepatitis, COVID-19).
• It is used in highly transmissible diseases.
• It is used in infants <1 year.

Q. If a person died due to COVID-19, which postmortem technique is required?

Ans: If there is a hospital report, there is no requirement of conducting PME, because it is a transmissible disease. If it is a medicolegal case, the Rokitansky/in-situ method is performed.

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Types of Incisions 

• A. I-shaped Incision
  • Most common type.
  • It starts from the chin to pubic symphysis.
• B. Y-shaped Incision
  • Purpose is cosmetic, to preserve the mamillary line.
  • It starts from the acromion process preserving the mamillary line reaches the breast, then to the xiphi-sternum and to pubic symphysis.
• C. Modified Y-Shaped Incision
  • This is done in fictional deaths (hanging, drowning).
  • It starts from MP (mastoid process) to SSN (suprasternal notch) then to pubic symphysis.
• D. X-incision
  • It is generally not done.
  • Two incisions are made from the shoulders to opposite iliac crests.
  • It makes an X-mark on the body.
  • It is for deep injuries/ custodial deaths.
• E. Inverted Y-Shaped Incision
  • It is generally not done.
  • It starts from the chin and just above the umbilicus it divides into two incisions.
  • It is done in infants.
• F. T-Shaped Incision
  • It starts from shoulder to shoulder, an incision is done in the middle.

Important Information  Most common is I-Shaped. In females it is Y-Shaped for cosmetic purposes. In fictional cases it is a Modified Y-Shaped Incision X-incision Two incisions are made from the shoulders to opposite iliac crests, in custodial deaths. Inverted Y-Shaped Incision It starts from the chin and just above the umbilicus it divides into two incisions, in infants. T-Shaped Incision It starts from shoulder to shoulder, an incision is done in the middle, not generally used nowadays.

Body Cavity to be Opened First

• Generally, in PME, the thoracic cavity is opened first.
• In specific cases like.
• A. Newborn
  • Abdomen is to be opened first.
  • Because the position of the diaphragm is seen.
  • If the position of the diaphragm is lower, it is a live bone.
  • If the position of the diaphragm is higher, it is a dead bone.
  • We can estimate that the respiration has taken place or not.
• B. Poisoning
  • In suspected cases of poisoning, the first cavity to be opened is the cranium.
  • Because the best smell of the poison can be perceived by the brain.
• C. Asphyxial Deaths
  • In this, Cranium-Thoracic-Abdomen-Neck (C-T-A-N) are opened in order.
  • Because we want the neck as a bloodless field.
  • Eg: In a throttling case, we have multiple bruises around the neck, if blood from other cavities enters the neck it would be a wrong finding.
  • Hence, the last cavity opened is the neck.
• D. Traumatic Head Injury
  • Head is the first cavity to be opened.
  • Some books may have a head as the last cavity to be opened, but follow as first.
• E. Air-Embolism/ Pneumothorax
  • Pneumothorax means the air in the pleural cavity.
  • In pneumothorax cases, the chest cavity (Thorax) is opened first, the skin flap is taken out and it is filled with water.
  • Then puncture the pleura, if a bubble comes out, the water test is positive (Pleura has air).
  • In air embolism cases, open the pericardium, fill it with water, and puncture the ventricle.
  • If a bubble comes out, the water test is positive (Pleura has air).
  • Another technique used in air embolism cases, a syringe is taken (pyrogallol), and aspirate blood from the ventricle.
  • If air is present in the ventricle, the color of the pyrogallol solution turns brown.

Organs to be Dissecte

• A. Brain
  • It is the most sensitive organ.
  • It can be dissected with/ without fixation.
  • Fixation is done with 10% formalin in a bucket with a string for 1 week if brain study is important.
  • A 1 cm interval is made in the coronal section of the brain.
• B. Heart
  • We use the inflow-outflow technique.
  •  Right atrium-Right ventricle, then to pulmonary artery we dissect up to the Lungs.
  • Left atrium-Left ventricle, then dissect up to the Aorta.
• C. Spinal cord
  • Spinal cord can be opened anteriorly and posteriorly.
  • Posterior opening is considered a better technique.
  • It is opened in spinal cord poison cases like strychnine and traumatic spinal injuries.
• E. Stomach
  • It is done by the Double Ligature Method, in both cardiac and pyloric ends.
  • It preserves the contents of the stomach.
  • It is opened in the greater curvature.
  • Because, in cases like acid or corrosive poisoning, the maximum damage is on the lesser curvature (Magenstrasse)
  • To examine the lesser curvature, it opened from greater curvature by the double ligature method.
• F. Intestine
  • Small intestine is dissected from the mesenteric border.
  • Large intestine is dissected from the Anterior tenia.
• G. Liver
  • Liver is dissected by Parallel dissection technique.

Exhumation

Important Information  In the court of law chapter, Exhumation is digging out of the dead body in presence of a magistrate.

• It is done in the presence of a magistrate, police, doctor.
• It comes under section 176 (3) CrPC.
• After digging out of the body, a secondary autopsy is done if needed.
• Identify the site with the help of relatives or the accused.
• It is done early in the morning because the whole daylight is required.
• There is no limit for exhumation, it might continue for a few days too.
• Soil sample (500gm) from the body and control sample is also taken, to make a comparison.
• Bones and tissues are taken for chemical or toxicological analysis.
• Arsenic present in the soil can go into the dead body, this process is known as postmortem inhibition.

Definitions

Antemortem thrombus: It is a firm, dark red, striae of Zahn (fine white line of fibrin), coralline platelet thrombus (alternate layers of platelets and fibrin).

Q. What is the striae of Zahn?

Ans: It is a fine white line of fibrin.

Q. What is the coralline platelet thrombus?

Ans: It is the alternate layers of platelets and fibrin.

Postmortem Clot

• Red current jelly: Blood clots rapidly
• Chicken fat clot: The clotting process is slow

Sudden Death

• Death is said to be sudden when a person not known to have been suffering from any dangerous disease, injury, or poisoning is found dead or dies within 24 hours after the onset of terminal illness.
• Left anterior descending artery (LAD) within 2 cm of its origin is the mostly affected.
• LAD is also called a Widow artery.

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