Forensic Autopsy

What are the primary goals of a forensic (medicolegal) autopsy?

Determine cause of death

Determine manner of death

Estimate time of death

Identify the deceased

Collect and preserve evidence

Document injuries and disease

Reconstruct events surrounding death

Provide expert courtroom testimony

What is cause of death?

Injury or disease initiating the fatal sequence

What is mechanism of death?

Physiologic derangement produced by the cause (ex. hemorrhagic shock)

What is manner of death?

Classification of how death occured

What are the five manners of death?

Natural

Accident

Suicide

Homicide

Undetermined

Which deaths require medicolegal investigation?

Violent deaths

Suspicious deaths

Sudden unexpected deaths

Deaths without physician attendance

Which medicolegal deaths are actually natural?

Many sudden natural deaths (especially cardiac deaths) require investigation because no physician can certify the death

What are the two largest categories of medicolegal deaths?

1. Sudden natural deaths

2. Accidental deaths (MVCs, overdoses, falls)

What is the basis of the coroner system?

Elected official

Historical English system

May not have medical training

May order autopsies

What is the basis of the medical examiner system?

Physician

Modern medical system

Usually forensic pathologist

Performs/Interprets autopsies

Which system generally provides greater medical expertise?

Medical examiner system

What determines the severity of blunt force trauma?

Amount of force

Duration of force

Body region struck

Surface area involved

Nature of object

What are the four major blunt force injuries?

Abrasion

Contusion

Laceration

Fracture of skeleton

What is an abrasion?

Removal of superficial epidermis by friction

What color are antemortem abrasions?

Red-brown

What color are postmortem abrasions?

Yellow/Translucent

What are the three types of abrasions?

Scrape

Impact

Patterned

What is a scrape abrasion?

Scrapes off the superficial layer of skin

If down to dermis → Serosanguinous fluid will be on the surface

Sometimes gravel, dirt, or glass may be embedded

What is a impact abrasion?

Blunt force strikes skin perpendicularly, crushing the epidermis

Where are impact abrasions most common over in unconscious face plant?

Eyebrows

Nose

Cheekbone

What is a patterned abrasion?

Variation of impact abrasion

• Like pipe or marks of structures like grills

When does scab formation begin?

4–18 hours

When does epithelial regeneration occur?

30–72 hours

When does subepithelial granulation and epithelial hyperplasia develop?

5–8 days

When does regression begin?

Around 12 days

What is a contusion?

Hemorrhage into soft tissue from blunt trauma without skin disruption

• Can be present in skin and multiple internal organs

What factors influence bruise size?

• Age

• Anticoagulants

• Tissue vascularity

• Health status

• Location

Bruise size does not necessarily reflect force

What color changes occur as bruises age?

Red → Blue/Purple → Green → Yellow → Resolution

Which bruise color provides the only reliable age estimate?

Yellow indicates the bruise is greater than 18 hours old

What is a laceration?

A tear produced by crushing or shearing force

How do lacerations differ from incised wounds?

Laceration	Incised wound
Torn	Cut
Tissue bridges present	No tissue bridges
Ragged margins	Sharp margins

What are mechanisms producing fractures?

Traction

Angulation

Rotation

Compression

Combined mechanisms

What is traction?

Bone pulled apart by traction

What is angulation?

Bone bent until snaps

What is the outcome of a rotational-bone twisted?

Spiral fracture

What is a vertical compression?

Bone shoved into bone

Which fracture results from angulation + compression?

Curved fracture line

Which mechanism commonly produces oblique fractures?

Angulation + rotation + compression

How quickly do fractures heal?

Children: 2–3 months

Adults: 3–5 months

Where are blunt-force defense wounds usually located?

Hands

Wrists

Forearms

Arms

What are impact injuries injuries?

Direct blow

Skull fractures

Brain contusions

What are acceleration/deceleration injuries?

Brain moves inside skull

Diffuse axonal injury

Subdural hematoma

Which hemorrhage is classically associated with acceleration/deceleration injury?

Subdural hematoma

What are the additional accidental deaths?

Auto accidents

Drug overdose

Falls in elderly persons

What mechanical components might produce scrap abrasions?

Nooses

Ligatures

What are some valuable evidence produced by contusions?

May reflect the configuration of the object used to produce it

Size and severity of contusion not always indicative of amount of force

What can produce linear lacerations?

Long thin objects

What type of lacerations do flat surface objects produce?

Irregular or ragged or y-shaped lacerations

When does a fracture occur?

When a large force is applied over large area resulting in extensive soft tissue injuries and often comminuted fractures

• Most crush fractures caused by vehicle-pedestrain accidents

What are the two types of blunt force injuries of head and neck?

Impact injuries

Acceleration/Deceleration injuries

What facial bones are mainly fractures by assault/motor vechile accidents?

Mandible

Maxilla

Zygoma

Zygomatic arch

What are the five categories of maxillary fractures?

Dentoalveolar

Le Fort I, II, III

Sagittal

What can affect skull fractures?

Skin thickness, application of force

Whether strikes a hard surface

Basilar skull fractures — Base of skull is weak

What are the most common brain injuries?

Caused by contusions

Most found in frontal or temporal lobes

Contrecoup lesions are directly opposite point of impact

What are the four types of rib fractures?

1. Spontaneous

2. Therapeutic

3. Direct localized violence

4. Indirect violence

What complications can be the result of a rib fracture?

Hemothorax

Pneumothorax

Lung laceration

Cardiac injury

Pneumonia

Empyema

Which side are CPR rib fractures most common?

Left

What cardiac injuries occur with blunt trauma?

Pericardial rupture

Cardiac contusion

Valve rupture

Papillary muscle rupture

Chordae tendineae rupture

What is commotio cordis?

Sudden cardiac arrest from blunt chest impact without structural heart injury

How does commotio cordis typically happen?

Baseball

Hockey puck

Martial arts

What are the mechanisms of lung injury?

Bronchial compression

Sternum compression

Shearing

Deceleration

Can result in hemothorax

What are common abdominal/pelvis organ blunt force injuries?

Liver laceration

Splenic rupture

GI injury

What is the most common cause of lower extremities injuries?

Automobile pedestrian accident

How do animal bites usually present?

Sharp and blunt force trauma

Dog usually exsanguination or injuries to vital organs

Sharks massive soft tissue and vascular damage → Exsanguination or drowning

What are the four types of sharp force wounds?

Stab

Incised

Chop

Therapeutic/Diagnostic

What is a stab wound?

A wound deeper than it is longer

• Usually from a single-edged knife

  • Square tip

  • V-shapred tip

True or false: Wound depth equal knife length

False

How do Langer lines affect stab wounds?

Parallel → Narrow slit

Perpendicular → Wider wound

Which body region contains most fatal stab wounds?

Left chest

• Heart, lung

What is an incised wound?

A wound that is longer than deep

• No relation to size of blade or object

What are hesitation marks?

Multiple shallow cuts suggesting tentative self-inflicted injury

Where are defensive incised wounds commonly found?

Palms

Back of forearms

Upper arms

What is a chop wound?

Heavy sharp instrument producing both cutting injury and underlying bone fracture

What is a bullet injury?

Kinetic energy (12 mas x velocity)

Bullet goes through the body like a boat on a lake

• Wound

Creates a “wake” when passing through

When is the temporary cavity largest?

When the bullet yaws (turns sideways) or fragments

What are the characteristics of contact gunshot wounds?

Stellate appearance

Soot in wound

Powder in wound

Vaporized metal

Gas enters wound

Where are stellate contact wounds most common?

Head

What is the extent of bullet injuries due to?

1. Mechanical shredding/crushing of tissue → Bullet

2. Shearing, compression, stretching to tissue → Wake

3. Secondary injuries → Bullet fragments

What is the maximum cavity for bullet wounds?

At point which maximum rate of loss of kinetic energy

• Occurs when bullet:

  • Turns sideways

  • Fragments

How are contact wounds produced?

When the muzzle of the gun is held against body at time of discharge

What is powder tattooing?

Reddish-brown punctate abrasions from unburned gunpowder

Cannot be wiped away

How are near contact/intermediate range wounds produced?

When the muzzle of the gun is not quite in contact with the skin

• Very short distance

Characterized by powder grains marks (powder tattooing)

How are distant wounds produced?

When the muzzle is sufficiently too far away that the soot nor powder is tattooed

• Irregular, cruciform, or stellate wounds can occur usually thin skinned area

What are the characteristics of entrance wounds?

Smaller

Round/oval

Abrasion collar

What are the characteristics of exit wounds?

Larger

Irregular

Usually no abrasion ring

At close range, which guns are most destructive?

Shotgun

What are other types of bullet wounds?

Grazing

Superficial perforating wounds

Reentry wounds

Rifle, shotgun wounds

What are the four major categories of asphyxia?

Suffocation

Strangulation

Hanging

Chemical

What are the four classic autopsy findings of asphyxia?

Petechiae

Cyanosis

Visceral congestion

Fluid blood

What causes petechiae?

Rupture of small venules from increased venous pressure

Where are petechiae commonly found?

Conjunctiva

Sclera

Epicardium

Pleura

What is the causes of suffocation?

Environmental oxygen depletion

Smothering

Choking

Mechanical asphyxia

Suffocating gases

What are some examples of mechanical asphyxia?

Vehicle rollover

Human pile

Positional asphyxia

What are the risk factors of positional asphyxia?

Alcohol intoxication

Drug intoxication

Entrapment

What are the three forms of strangulation?

Hanging

Ligature

Manual

What are the three forms of suffocation?

Environmental

Entrapment

Smothering

Most common manner of death in hanging?

Suicide

Internal neck injuries are common or rare?

Rare

What causes death in judicial hanging?

Cervical spine fracture-dislocation

What are the classic autopsy findings for strangulation?

Facial congestion

Conjunctival petechiae

Neck hemorrhage

Hyoid fracture

Thyroid cartilage fracture