External Examination and Postmortem Changes

What is the purpose of the gross description during an autopsy?

To accurately document all findings so another person could mentally recreate exactly what was observed during the examination

What is the very first step of an autopsy external examination?

Confirm the identity of the decedent using identification tags

What personal items should always be examined before beginning the external exam?

Clothing

Jewelry

Diapers (if present)

Other attached personal belongings

What are the three major components of the external examination?

1. Examine the native body (e.g., postmortem changes)

2. Evaluate medical interventions

3. Document scars, injuries, and trauma

What are some examples of medical interventions that should be documented during the external exam?

Tracheostomy tube

Endotracheal tube

Central venous catheter

Chest tubes

IV lines

Pacemaker

Defibrillator

What are some examples of injuries that should be documented on the external exam?

Surgical scars

Abrasions

Ecchymoses

Needle marks

CPR injuries

Lacerations

Gunshot wounds

What body regions should be examined systematically?

Head

Neck

Torso

Upper extremities

Lower extremities

Genitalia, perineum, groin

Which anatomical terms should be used when describing lesion location?

Superior

Inferior

Medial

Lateral

Anterior

Posterior

Why are "flexor" and "extensor" preferred when describing forearm lesions?

Because forearms can assume different positions, making anterior/posterior descriptions inaccurate

What additional directional terms are commonly used for the forearm?

Radial

Ulnar

How is body frame generally described?

Small frame

Medium frame

Large frame

How should skin color be documented?

Objectively by skin pigmentation rather than race

Examples:

• Light-skinned

• Brown

• Dark-skinned

Why should terms like "Caucasian" or "African-American" be avoided in gross descriptions?

Because they describe ethnicity rather than objective physical findings

What is livor mortis?

Gravity-dependent pooling of blood within blood vessels after death

How is livor mortis assessed?

Firmly press the skin for at least 5 seconds and observe whether blanching occurs

When does livor mortis first become visible?

Approximately 30 minutes after death

What causes fixed livor mortis?

Blood becomes permanently settled and no longer shifts with body position

Why can livor mortis be mistaken for bruising?

Both produce skin discoloration

Difference:

• Livor = blood remains inside vessels

• Contusion = blood leaks into surrounding tissue

What is rigor mortis?

Stiffening of muscles after death caused by ATP depletion

How is rigor mortis evaluated?

Flex and extend joints

Which muscles develop rigor first?

Jaw muscles

What is the progression of rigor mortis?

Jaw → Upper extremities → Lower extremities

When does rigor mortis begin?

Approximately 2 hours after death (1-6 hours)

How long does rigor mortis typically last?

36–48 hours in temperate climates

What factors accelerate rigor mortis?

Exercise

Heat

Fever

What is algor mortis?

Cooling of the body after death

Why is body temperature unreliable for estimating time of death?

It is influenced by:

• Environment

• Clothing

• Initial body temperature

• Airflow

• Body habitus

How is pitting edema assessed?

Apply firm pressure for 5 seconds over soft tissue such as the medial lower legs

What is ecchymosis?

Skin discoloration of unknown cause

What is a contusion?

Ecchymosis caused specifically by blunt force trauma

If the cause of discoloration is uncertain, which term should be used?

Ecchymosis

What are common forms of biologic evidence?

Blood

Semen

Hair

Tissue

Fingernails

Bite marks

Saliva

What non-biologic evidence may be collected?

Clothing

Bullets

Fibers

Paint

Glass

Soil

What evidence is commonly collected during an autopsy?

Fingernail clippings

Vaginal swabs

Oral swabs

Rectal swabs

Gunshot residue

Hair

Clothing fibers

Which cells are useful for DNA testing?

Nucleated cells

Which laboratory method is commonly used for forensic DNA analysis?

PCR (Polymerase Chain Reaction)

What are the three possible DNA comparison results?

1. Inadequate sample

2. Exclusion

3. Match

What factors are used when estimating time of death?

Livor mortis

Rigor mortis

Body temperature

Vitreous potassium

Stomach contents

Environmental evidence

Why is vitreous potassium considered unreliable?

It shows significant variability and should not be used alone

Why are stomach contents an unreliable estimate of time of death?

Digestion varies with:

• Meal composition

• Individual differences

• Stress → Stops digestion

• Health status

What environmental clues may help estimate time of death?

Insect activity

Uncollected mail

Newspapers

Receipts

Weather

What is autolysis?

Self-digestion by endogenous enzymes

Which organ undergoes autolysis particularly rapidly?

Pancreas

What is putrefaction?

Tissue breakdown by bacteria, primarily from the GI tract

What accelerates putrefaction?

Warm temperatures

Sepsis

What is the first visible sign of decomposition?

Green discoloration of the abdomen

What occurs after abdominal discoloration?

Green-black discoloration of the face and neck with swelling

What is purge fluid?

Reddish fluid exiting the nose and mouth during decomposition

What causes marbling?

Green-black discoloration tracking along superficial blood vessels during decomposition

What happens to the skin during advanced decomposition?

Skin slippage

What happens to the scalp hair during decomposition?

Hair slips out easily

What eventually happens to the brain?

Liquefaction

What methods are used to identify a decedent?

Identification tags

Facial photographs

Fingerprints

Height

Weight

DNA

Dental comparison

Why are fingerprints useful for identification?

Unique to every individual

Remain unchanged throughout life

What is compared during forensic dental identification?

Postmortem dental examination with antemortem dental records

How many permanent teeth does a normal adult have?

32

What characteristics make good autopsy photographs?

Clean specimen

Proper orientation

Neutral background

Minimal glare

Good lighting

Why is radiography performed during an autopsy?

Detect bullets

Identify fractures

Locate foreign bodies

Assist with identification

What are nonscientific method for ID?

Sex

Age

Race

Stature

Hair color

Eye color

Amputations

Where can DNA samples be taken?

Postmortem sample of whole blood

Hair

Skin

Bone marrow

Seminal fluid

(Must contain nucleated cells)

How are dental records used?

Compare decedents teeth with antemortem records