Complete Postmortem Techniques Guide

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 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.

Introduction

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. The 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. 

Autopsy Types

A. Medicolegal Autopsy

It is on the inquest of either police/magistrate. Section 174 CrPC for police inquest and Section 176 CrPC for magistrate inquest. This autopsy is chosen for unnatural deaths. A Relative’s  consent is not required fort this autopsy. 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. The 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 and a RMP (Registered Medical Practitioner).

B. Pathological/Clinical Autopsy

Relative consent is mandatory in Pathological/ clinical Autopsy. It is mostly done in case of 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. Thus type of autopsy is for academic purposes or to improve knowledge. It is done by RMP (Registered Medical Practitioner).

C. Psychological Autopsy

A person committed suicide usually undergoes 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 and relatives

D. Virtual Autopsy

It is a visual imaging technique performed in developed countries. CT scan and MRI is performed to know 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. The 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 

This is the most common method of postmortem. The organs are removed One-by-one. It is a very Fast and easy method.

B. Ghon’s/ en-Block Method (G-B)

In Ghon’s postmortem technique a targeted block (C/T/A/P) 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. Here the Inter-organ relations are intact.

C. Lettule’s/ en-Masses/ Evisceration

In lettuce’s postmortem method large masses (C+T+A+P) are taken out. Complete viscera is taken out (Evisceration) and the Blood vessels and vascular supply are intact. It is  done so that there is minimum bleeding.

D. Rokitansky/ In-situ Method

It is an inside dissection done for usually infectious diseases such as HIV, Hepatitis, COVID-19. It is used in highly transmissible diseases. It is used in infants <1 year.

Types of Incisions

A. I-shaped Incision

It is the most common type of incision made. It starts from the chin to pubic symphysis.

B. Y-shaped Incision

The main purpose of Y shaped incision is cosmetic that is 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 case of  fictional deaths (hanging, drowning). It starts from mastoid process to the suprasternal notch and then to pubic symphysis.

 D. X-incision

It is generally not done. Here, the two incisions are made from the shoulders to opposite iliac crests. It makes an X-mark on the body. It is done for deep injuries/ custodial deaths.

E. Inverted Y-Shaped Incision

It is generally not done. The incision starts from the chin and just above the umbilicus it divides into two incisions. It is usually done in case of infants.

F. T-Shaped Incision

T shaped incision starts from shoulder to shoulder, an incision is done in the middle.

Body Cavity to be Opened First

A. Newborn

Abdomen is to be opened first in a newborn’s postmortem because the position of the diaphragm is to be noted. If the position of the diaphragm is lower, it is a live newborn that was killed. If the position of the diaphragm is higher, it was a dead baby or still birth. Here, 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 asphyxial death, Cranium-Thoracic-Abdomen-Neck (C-T-A-N) are opened in order because we want the neck as a bloodless field. For 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 in case of traumatic head injury.

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 pleura is punctured, 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 Dissected

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 in case of heart dissection. 

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. This method 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

The Small intestine is dissected from the mesenteric border and the Large intestine is dissected from the Anterior tenia.

G. Liver

Liver is dissected by Parallel dissection technique.

Exhumation

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. The site of burial is found 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. In case of arsenic present in the soil can go into the dead body, this process is known as postmortem inhibition.

Frequently asked Questions:

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

Ans: Arsenic poisoning.

Q. Which method of postmortem is used for least bleeding?

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

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.

Q. What is the striae of Zahn?

Ans: It is a fine white line of fibrin. It is also known as Antemortem thrombus

Q. What is the coralline platelet thrombus?

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

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