2. External Examination & Postmortem Changes

Reading: Connolly (Atlas): Ch. 4 (Basic Postmortem Examination – external portion), Ch. 7 (Photography – intro) Di Maio (Handbook): Ch. 2 (Physical Evidence), Ch. 3 (Time of Death), Ch. 4 (Identification)

What is the purpose of the gross description in an autopsy report?

To accurately record the findings of the postmortem examination so the reader can visualize and recreate exactly what was observed at autopsy.

What should a well-written gross description allow the reader to do?

Visualize and recreate the autopsy findings, including being able to draw what was observed.

What is the first step of the external examination?

Confirm the identity of the decedent and verify the location and contents of all identification tags.

Besides clothing, what item should also be examined and documented in hospitalized children and adults during the external examination?

The contents of any diaper present on the body.

How many phases does the external examination consist of?

Three phases.

What is the first phase of the external examination?

Examine the native body, including postmortem changes.

What is the second phase of the external examination?

Evaluate medical interventions, such as tracheostomy tubes and cardiovascular access lines.

What is the third phase of the external examination?

Document scars and other injuries, including those resulting from medical interventions (e.g., CPR abrasions, ecchymoses from vascular access).

Why is it important to recognize injuries caused by medical interventions during the external examination?

To distinguish therapeutic or resuscitative injuries from injuries related to disease or trauma.

Which body regions are included in the torso during the external examination?

The chest and abdomen (anterior) and the back (posterior).

Which structures are included in the upper extremity during the external examination?

The shoulder, arm, elbow, forearm, wrist, and hand.

Which structures are included in the lower extremity during the external examination?

The hip, thigh, knee, lower leg, ankle, and foot.

Which anatomic regions should be included in a complete external examination?

Head, neck, torso, upper extremities, lower extremities, genitalia, perineum, and groins.

In what position is the body assumed to be when using standard anatomic terminology?

The standard anatomic position (i.e., Da Vinci's man).

What are the standard anatomic directional terms used to describe findings on the body?

Superior, inferior, lateral, medial, anterior, and posterior.

Why are flexor/extensor and radial/ulnar descriptors preferred for lesions on the forearm?

Because the forearms may be positioned differently (e.g., defensive posture or running), making standard anatomic terms less accurate.

Which terms are preferred when describing lesions on the forearm?

Flexor or extensor aspect, and radial or ulnar aspect.

How should body build be documented during the external examination?

As small frame, medium frame, or large frame.

How should skin color be documented during the external examination?

Using objective descriptive color terms rather than race or ethnicity.

Which skin color descriptors are recommended in an autopsy report?

White or light-skinned, brown, black or dark-skinned.

Which terms should be avoided when documenting skin color in an autopsy report?

Racial or ethnic descriptors such as Caucasian, African-American, or Asian.

How is livor mortis assessed during the external examination?

By firmly pressing the affected area for at least 5 seconds and then releasing the pressure to assess blanching.

How is rigor mortis assessed during the external examination?

By flexing and extending the joints to evaluate muscle stiffness.

How should pitting edema be assessed during the external examination?

By firmly pressing affected soft tissues, such as the medial lower legs or medial thighs, for approximately 5 seconds.

What is ecchymosis?

An area of discoloration of unknown etiology.

What is a contusion?

An ecchymosis caused specifically by blunt force trauma (a bruise).

If the cause of a skin discoloration is uncertain, which term should be used: ecchymosis or contusion?

Ecchymosis.

What are the two major categories of physical evidence collected during a forensic investigation?

Biologic evidence and nonbiologic evidence.

What types of biologic evidence may be collected during a forensic investigation?

Blood, semen, hair, tissue, fingernails, bite marks, and saliva.

What types of nonbiologic evidence may be collected during a forensic investigation?

Clothing, bullets, fibers, paint, glass, and soil.

Why should clothing be examined before collection?

To identify materials adherent to the clothing, such as fibers and hair.

Which collection tube should be used for blood intended for DNA analysis?

A lavender-top tube.

How should dried blood evidence be collected?

By scraping it into a sterile test tube.

How should semen evidence be collected in a suspected sexual assault?

Using two cotton swabs from the vagina, rectum, and mouth as indicated.

How should hair evidence be collected in a suspected sexual assault?

Collect adherent hairs from the body and comb the pubic hair.

How should tissue evidence be collected?

Using clean forceps (pickups) and placing the tissue into a sterile tube.

How are bite marks used as forensic evidence?

They are compared with a suspect's dentition for identification.

How should clothing be packaged as evidence?

Each item should be placed individually in its own bag or box.

How should bullets be handled during evidence collection?

They should be collected while wearing gloves.

How are fibers, paint, and glass commonly analyzed?

By examining their physical properties, such as chemical composition.

Which cells are suitable for DNA analysis?

Nucleated cells.

What are the three possible outcomes of DNA analysis?

1) Inadequate sample 2) DNA profile exclusion (profiles are different) 3) DNA profile match.

Which laboratory method is commonly used for forensic DNA analysis?

Polymerase chain reaction (PCR).

What findings should be integrated when estimating the postmortem interval (PMI)?

Livor mortis, rigor mortis, algor mortis (body temperature), vitreous chemistry, stomach contents, environmental conditions, and scene findings.

What causes pale areas within livor mortis?

Compression of dependent body areas against a hard surface prevents blood from settling (contact flattening).

How can livor mortis be distinguished from a contusion during an autopsy?

A contusion contains blood in the extravascular tissues, whereas livor mortis consists of blood remaining within intact blood vessels.

Which muscles typically show rigor mortis first?

The smaller muscles of the face and jaw.

In what order does rigor mortis generally progress?

It first becomes apparent in the face and jaw, then progresses to the upper extremities, trunk, and lower extremities.

Approximately when does rigor mortis begin?

Approximately 1–6 hours after death (often first noticeable around 2 hours).

When is rigor mortis typically fully developed?

Approximately 12–24 hours after death.

When does rigor mortis usually begin to resolve?

Approximately 24–48 hours after death.

How does strenuous physical activity before death affect rigor mortis?

It accelerates the onset of rigor mortis by depleting ATP stores.

How does environmental temperature affect rigor mortis?

Heat accelerates its onset and resolution, while cold delays both.

Why is body temperature alone an unreliable indicator of the postmortem interval?

Because cooling is influenced by many variables, including ambient temperature, clothing, body habitus, humidity, air movement, and the body's initial temperature.

Can body temperature still contribute to estimating the postmortem interval?

Yes. It is most useful during the first 24 hours after death but should always be interpreted with other postmortem findings.

Is postmortem vitreous potassium a precise method for estimating the postmortem interval?

No. Vitreous potassium may help corroborate the postmortem interval, but it is highly variable and should never be used as the sole indicator of time of death.

Why is vitreous potassium interpreted cautiously in forensic pathology?

Because significant biologic and environmental variability limits its accuracy, so it should only be used as supportive evidence.

How can stomach contents assist in estimating the postmortem interval (PMI)?

If the time of the last meal is known, the degree of digestion may help estimate the PMI.

Why should stomach contents be interpreted cautiously when estimating the PMI?

Because digestion varies from meal to meal, person to person, day to day, and may be slowed or stopped by stress.

How can insect activity assist a forensic investigation?

Different insects colonize the body at different times and can help estimate the postmortem interval.

What are examples of nonscientific markers that may assist in estimating the time of death?

Newspaper accumulation, uncollected mail, and dated receipts found with the decedent.

What is the first visible stage of putrefaction?

Greenish discoloration of the skin over the abdomen.

What changes occur after the initial green discoloration during decomposition?

Green-black discoloration of the face and neck with swelling and protrusion of the tongue and eyes.

What is purge fluid?

A reddish fluid that exits the nose and mouth during decomposition.

What causes body swelling during decomposition?

Gas production by bacteria during putrefaction.

What changes accompany gas-related swelling during decomposition?

Skin slippage and marbling as the skin changes from green to black.

What happens to the hair during advanced decomposition?

It slips from the scalp.

What happens to the brain during advanced decomposition?

It liquefies.

What identification procedures should be completed when a body arrives at the morgue?

Apply a wrist or ankle identification tag, obtain a facial photograph, collect two complete sets of fingerprints, record height and weight, and collect blood for DNA.

Why are two complete sets of fingerprints obtained during identification?

To ensure accurate identification and provide a complete permanent record.

What characteristics make fingerprints useful for identification?

No two individuals have identical ridge patterns, the ridges remain unchanged throughout life, and the patterns allow systematic classification.

How are dental records used to identify an unknown decedent?

Postmortem dental findings are compared with antemortem dental records.

Besides comparison with antemortem records, what documentation is performed during dental identification?

The teeth are radiographed and photographed.

How many permanent teeth does a normal adult have?

Thirty-two.

Which postmortem specimens can be collected for DNA analysis?

Whole blood, hair, skin, bone marrow, and seminal fluid.

What characteristic must a specimen have to be suitable for DNA analysis?

It must contain nucleated cells.

What is meant by nonscientific methods of identification?

Identification based on physical characteristics such as sex, age, skin color, stature, hair color, eye color, and amputations.

Why are nonscientific methods of identification considered less reliable than scientific methods?

Because physical characteristics may be shared by multiple individuals and can change over time or after death.

What factors contribute to obtaining high-quality forensic photographs?

An appropriate camera, a clean background, proper photographic technique, good specimen preparation, correct orientation, and minimizing light reflection.

Why is proper specimen preparation important before photographing an autopsy specimen?

A well-dissected specimen allows important findings to be clearly demonstrated and documented.

Why should organs be photographed in their anatomic orientation?

To accurately demonstrate normal anatomy and the location of pathologic findings.

Why should light reflection be minimized during forensic photography?

To prevent glare from obscuring important findings.

What type of radiographic equipment is commonly used in the autopsy suite?

A cabinet low-voltage X-ray machine.