Post mortem techniques and mechanical injuries Flashcards
Types of autopsy
1. Medicolegal autopsy: done by forensic pathologist whole body PM 2. Pathological autopsy: Academic purpose Consent of relatives Part of body 3. Negative autopsy: 4. Obscure autopsy 5. Virtual autopsy: non invasive methods 6. Psychological autopsy
Causes of negative autopsy
- Vagal inhibition
- Laryngospasm
- Thyrotoxicosis
- Adrenal insufficiency
Difference between negative and obscure autopsy
Negative autopsy: 2-5% of whole PM No cause of death even after various types of medical investigations Obscure autopsy: No definite cause of death after PM
Psychological autopsy
Done in suicide cases
Questions asked to family members and friends to know mental status of the person at the time of committing suicide or before that
Types of incisions used in PM
- I shape: most common
- Y shape:
acromian process to
in females - Modified Y shaped:
Suprasternal notch
To preserve neck (hanging,…) - Inverted Y shape:
Infant
Methods of post mortem
- Virchow’s method
- Rokitansky method
- Ghon’s method
- Lettule’s method
Virchow’s method
Most common method of post mortem
One by one organ removal
Rokitansky method
In situ method of PM examination
In infants
If infected with HIV, HBV,…
Ghon’s method
A method of PM examination
Separate organ blocks
En block dissection (cervical, thoracic,…)
Stomach PM dissection
Opened from greater curvature
Spinal cord PM dissection
Best technique is posterior technique
Brain PM examination
Started from frontal area
1 cm slice is taken, starting from coronal plane
Then fixed in 40% formalin
Liver PM dissection
2 cm slice is made along with long axis
Heart, coronary artery PM examination
RA ➡️ RV ➡️ LA ➡️ LV
Coronary artery: 2-3 mm sections are made
Lettule method
En masse method of PM examination
All organs taken simultaneously in a mass
Antemortem thrombus
- Striae of Zahn
White lines of fibrin - Coralline platelet thrombi
Platelet + fibrin
Post mortem clot
Red current jelly and chicken fat appearance
Skull is opened via the methods
Beneke method:
2 halves
Barr method:
4 quarters
First cavity to be opened during post mortem
Head
Especially during:
1. poisoning cases (brain gives better smell than other organs)
2. Traumatic head injury
3. Air embolism
4. Asphyxia (neck is last so that we can get a bloodless field)
Cases in which the first cavity to be opened during PM is not the head
1. Infant: abdomen To observe the position of the diaphragm 2. Pulmonary air embolism: thorax Test used are:- 1. Water test bubble 2. Pyrogallol test
Undertaker fracture
Fracture of the invertebral disc between C6 and C7
Post mortem fracture
In an embalmed body the best specimen for toxicology analysis is
Skeletal muscle from buttocks
Exhumation on the request of magistrate is according to
176 CRPC
Done in day light, started early in the morning
No time limit
6 samples of soil (6 parts/sides of body) compared with control soil sample
Samples preserved to rule out any poisoning
Bone
Nail
Hair
Types of mechanical injuries
- Gravel rash/ abrasion
2. Contusion/ bruise
Gravel rash/ abrasion
Epidermis, dermis involved Types: 1. Grazed abrasion: By sliding due to friction- friction burn 2. Scratch abrasion- by nail, thorn, pin Linear 3. Patterned abrasion: • Pressure • Imprint/ impact
Brush burn abrasion
Special type of grazed abrasion
When you slide on road, a v-shaped abrasion with burning sensation happens
Types of patterned abrasion
1. Pressure: crushing 90° Eg., ligature mark in hanging, bite mark 2. Imprint/Impact abrasion Moving objects with a rough surface Eg., tyre marks
Age of abrasion
Using scab- dried lymph or blood after 12-24 hours Brown- 2-3 days Black - epithelia covers and grows in 4-7 days Falls after 7 days
PM abrasion
No vital reaction
Yellow
Common on bony prominences
Contusion/ Bruise
By blunt trauma causing clotted blood in dermis due to blood vessel rupture
Swelling is seen
Irregular margins
More visible in children and females and also in thin skin
Less visible on thick skin (palm, sole and abdomen)
Large bruises are seen in
Face
Vulva and scrotum
These organs are soft and vascular
Colour changes of bruises or contusions
Starts from periphery and goes to the centre
R. Red due to Hb V. Blue- deoxy Hb for a few hours to 3 days I. Blue B. Brown Hemosiderin on day 4 G. Green Hematoidin 5-6 days Y. Yellow Bilirubin 7-13 days O. Original and skin colour for >14 days
Pattern bruising / contusion
- Butterfly bruise: Battered baby syndrome (child abuse)
- Six penny bruise:
Coin shaped bruise
Eg., Throttling and child abuse - Tramline bruise/ Railway line bruise
Hitting with rod
Bruise where no colour change is present
Sub conjunctival haemorrhage is the only bruise where no colour change is present
Ectopic bruise/ migratory bruise
Impact and bruise are seen in different locations
1. Raccoon’s sign/ black eye:
In anterior cranial fossa fracture, bruise is seen in peri orbital
2. Battle sign:
In middle cranial fossa fracture, bruise is seen in mastoid tip
Artificial bruise is produced by
Plants like:
P. Plumbago
S. Semecarpus anacardium / Marking nut/ Bhilwanol
M. Madar/ Calotropis/ Akar
Characteristics of artificial bruise
Produced by plant products and not by injury No colour changes- just brown Only over accessible parts of body Regular margins Itching present Chemical test can be done to confirm
Test done for the confirmation of bruise
Incision test
Incise the skin and pour water
The clotted blood of bruise is not washed away
Laceration
Medical terminology for tear
Caused by heavy blunt force ➡️ splitting of epidermis/ dermis / subcutaneous tissue
Irregular margins
Crushed tissue bridges or fibres and crushed hair follicles are seen: confirmation
Types of laceration
- Stretch laceration: tangential force
- Shearing laceration: acute angle
• skin tissue separated: avulsion (eg., degloving)
• tissue is separated but attached with margin: flaying - Tear: normal laceration with bruised margins
- Cut laceration/ chop/ slash wound:
Spindle shaped gaping wound - Split laceration: force perpendicular to bony prominences
Incision
Parallel to skin surface by a sharp weapon
Longer than deep
Margins: clean cut
Confirmation: lens examination- cut tissue and hair follicle
Tailing phenomenon
Tailing phenomenon
At the end of an incision, the depth is less
Tailing decides the direction of weapon
Lacerated looking incised wound
In sites like scrotum and axilla (soft and relaxed), because of the rugosity the margins look irregular, leading to lacerated looking incised wound.
Confirm with lens.
Note: incised wound on genitalia: homicidal
Hesitational/ tentative/ trial cuts
Multiple superficial incised wound in wrist
Suicidal in nature
Age of incised wound
In hours: 12. Edges are red, swollen 24. Endothelial cells seen 36. Capillary network 48. Fibroblasts 3-5 days: collagen fibres 1-2 weeks: scar formation
Delayed bruise
Bruise occurs much later after impact
Seen in deep bruise
Infra red photography is used to see them
Grievous hurt
Emasculation
Permanent privation of sight of either eye
Privation of any member or joint
Permanent destruction of power of any member or joint
Permanent disfigurement of head out face
Fracture or dislocation of a bone or tooth
Any hurt which endanger life or which causes the victim to be in severe bodily pain, or which prevents the person from doing ordinary activities for a minimum period of 20 days
