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Transcript of Forensic Pathology - Dr
Forensic Pathology
Elizabeth J. Miller, M.D.
Forensic Pathology
Subspecialty of pathology concerned with identification of remains and determination of cause and manner of death
Forensic PathologyDeaths referred to the medical examiner
Violent deaths (accidents, suicides, homicides)Suspicious deathsSudden, unexpected deathsDeaths without a physician in attendanceDeaths in a penal institution
Cause of DeathThe process that initiates a chain of events resulting in death
Atherosclerosis MI/arrhythmiaGSW chest pneumoniaMVA repair of aortic laceration aneurysm at site 10 years laterBlunt force injury of head altered mental function aspiration pneumonia
Manner of Death
NaturalAccidentSuicideHomicideUndetermined
Manner of DeathNatural
AtherosclerosisPneumoniaCancerSequelae of ethanol/drug abuse
Perforation of gastric ulcer
Manner of Death
AccidentMVAEthanol/Drug overdoseDrowningGSWAsphyxia
Manner of DeathSuicide
GSWStab/incised woundDrug overdoseDrowningMVAAsphyxia
Manner of DeathHomicide
GSWStabDrug overdoseDrowningMVAAsphyxia
Manner of DeathUndetermined
Insufficient information about the circumstances surrounding death
Drug overdose—accidental overmedication or suicide
Cause of death unknown Skeletonized remains No anatomical/toxicological explanation
Scene InvestigationInvestigative/medical/legal conclusions rest on an intelligent and thorough scene investigation
IdentityApproximate time of deathImportant evidence/clues to circumstances surrounding death
Secure residence Signs of struggle Position of body/clothing Suicide notes Trash contents
Identification of Remains
Visual by relatives or friendsLocation of body (e.g. In home)ID cards distinctive feature (tattoo, ring, necklace)
Scientific Identification
Ante mortem radiographs/medical recordsSerology/DNADental recordsFingerprints
Chain of Evidence
Item properly identifiedItem stored so as to prevent tamperingMaintain record of what was done with object, by whom, at each change of hands
Establishing Time of Death
WitnessesPhysical evidence (mail, newspaper)Post mortem changes
PutrefactionInsect activity
Changes Associated With Death
Rigor MortisLivor MortisAlgor MortisDecomposition
Rigor MortisDepletion of ATPInvolves all muscles simultaneously and evolves at that same rate in all musclesMost evident in small muscles first
Classical presentation in order of appearance
Jaw upper extremities lower extremities
Onset and disappearance dependent on many variables
Rigor Mortis
No rigor—death < 3 hoursDeveloping rigor—death 3 to 9 hoursFull rigor—death > 9 hoursPassing rigor—death 24 to 48 hours
Duration of rigor shorter in warm environment
Rigor Mortis
Any activity or condition prior to death that results in decreased ATP accelerates development of rigor mortis
Violent/heavy exercise (cadaveric spasm)Severe convulsionsHigh body temperatures
Rigor Mortis
May be delayed in:Very weak or emaciated individualsInfantsCold/freezing temperatures
Livor MortisMechanism—settling of blood in dependent areas of body
Appears within 30 minutes after deathNon-fixed/blanching (< 8 to 12 hours)—blood still within capillaries and will shift with change in positionFixed/non-blanching (> 8 to 12 hours)—blood within tissue and will not shift with change in position
Livor Mortis
DiscolorationPurple—normal (venous blood)Green—sulfhemoglobin (hydrogen sulfide)Pink, cherry-red
Carboxyhemoglobin (carbon monoxide) oxygen (cyanide, hypothermia, refrigeration)
Livor Mortis
Important in determining post-mortem movement of body, not time of deathMay be confused with bruising
Bruises do not blanch with pressure
Fixation may be delayed by cool temperatures
Algor Mortis
Cooling of body by heat transfer following death
Conduction—direct contactRadiation—infrared raysConvection—air currents
Algor MortisInner core temperatures preferred—decline is slower/regular
RectalLiverBrain
Skin—cools rapidly from exposure to environment, so not useful
Algor Mortis
Under average conditions< 3 hours—2.0° F to 2.5° F / hour 3 to 12 hours—1.5º F to 2.0º F / hour12 to 18 hours—1.0º F / hour
Algor Mortis
Tables useful, but must be used within context of caseData tables assume:
Peri-mortem temp 98.6Constant post-mortem tempNo extremes in environmental tempOther scene variables
Decomposition/putrefaction
FreshBloatedActiveDry/skeletal
Decomposition
Bloated stage~ 36 to 48 hrs—marbling (breakdown of blood within veins) and skin slip/blistering~48 hrs—bloating (gas production)~48 to 72 hrs—green to black discoloration
Decomposition
Active decay3 days to several weeks
Variables: temperature, insect activity, bacteria
Dry/skeletal stage2 weeks in hot humid tempsMonths in snowYears if body changed by adipocere
Animal Activity
LandSea
Preserving ChangesMummification
Drying of body—usually in warm/dry climateSkin preserved, internal organs not always
AdipocereWaxy change of fat—usually in high humidity/waterConversion of unsaturated fatty acids to saturated fatty acids via Clostridia enzymes
Accelerating Changes
Injury sites—allow access to insectsAnything that promotes warmth
ObesityHeavy clothingSepsis
Natural Death—SIDS Usually occurs within 6 months, no more than 10 monthsExact mechanism unknown
Not caused by smothering or choking
Not contagiousNot hereditaryOccurs very quickly and is assumed to happen during sleep—no suffering or distress
Natural Death Presenting As SIDS
PneumoniaPyelonephritisMyocarditisBacterial meningitisMCAD deficiency
Other Cases Presenting As SIDS
Accidental suffocationChild abuse
Asphyxia
Asphyxia
Anything that interferes with oxygen uptake or utilization
SuffocationStrangulationChemical asphyxia
Suffocation
Failure of oxygen to reach bloodSmothering ChokingDrowningSuffocating gases (displacement of oxygen)
Hydrogen sulfide gas
Suffocation
Smothering—mechanical obstruction of nose and mouth
Plastic bagHandOverlying (can’t distinguish from SIDS)
Suffocation
Choking—requires an underlying explanation
IntoxicationNeurological disorderPsychiatric patient
Suffocation
ChokingAspiration of foodForeign objects
Suffocation
Mechanical asphyxia--compression of chest
Car/other heavy objectsBodies (riots, stampedes)Positional asphyxia
Cribs with mismatched mattressesIntoxicated adults
Suffocation
DrowningDry vs. wet drowningNeed to determine why person drowned
StrangulationExternal pressure causing closure of the blood vessels and tracheaPressures
4.4 lbs.—jugular veins11 lbs.—carotid arteries33 lbs.—trachea
Strangulation
HangingLigature Manual
Strangulation
HangingUsually suicidePoint of suspensionPOS superior to laryngeal prominence
StrangulationLigature
Usually homicideTransverse markEvidence of a struggle
Conjunctival petechiae Contusion of strap muscles Fracture of hyoid bone or superior horns of
thyroid cartilage
Strangulation—Manual
HomicideNeck holds (law enforcement)—usually no external injury unless flashlight or baton used
Carotid sleeper hold—obstruction of blood flow Rapid onset of unconsciousness—must release
immediately upon incapacitation Release—complete recovery in seconds
Choke hold—airway compression Serious damage/death within seconds Muscular or subcutaneous hemorrhage
Chemical asphyxiaCyanide—almond odor
Cherry red discoloration of tissues
Carbon monoxide50% carboxyhemoglobin lethal levelCherry red discoloration of tissuesQuick (6 to 7 minutes)Children and elderly especially sensitive
Burns and Electrocution
BurnsCategories
FlameContactRadiant heatScaldingChemicalMicrowave
Burns
Rule of ninesHead—9%Arms—9% (each)Anterior torso—18%Back—18% Legs—18% eachNeck or perineum—1%
BurnsDegree of injury
1st degree—confined to epidermis Skin red without blistering
2nd degree—destroys epidermis, spares dermis
blistering
3rd degree—destruction of dermis Skin surface brown or black
4th degree—destruction of subcutaneous structures (e.g. muscle)
Burns
Clothing is protectiveDeath
Immediate—smoke inhalationDelayed—sepsis from burns
BurnsMust establish
Identification of deceased Whether deceased was alive at the time of fireCause of deathManner of deathAny contributing factors
EtOH, drugs, natural disease
Burns75% of fire-related deaths due to inhalation of toxic smoke
Carbon monoxide (lethal level 50%) Children/small animals reach fatal level
quicker due to higher metabolic rate
Hydrogen cyanide (lethal level 5 mg/ml)
BurnsWeight and height alteredFeet and hands may be lostPugilistic pose—shrinkage of muscleBody of an adult rarely destroyed by house or car fire
House fire temp—1200 to 1600 FCrematorium temp—1800 to 2000 F
Children may be consumed by fire
Burns
Artifacts of burnsEpidural hematomaFire fractures of bone
Burns
ScaldingImmersionSplashSteam
Burns
Chemical burnsAcids (HCL)Bases (lye, bleach)Petroleum products (blistering)
Electrocution
ElectrocutionOhm’s law—V=IR (volts = current x resistance)Household current 110 volts (alternating)Resistance of skin
Dry—100,000 ohms (1.1 mamp) Wet—1,000 ohms (110 mamp)
ElectrocutionCurrent Physiologic effect1 mamp Slight tingle16 mamp Release wire due to shock20 mamp Muscular paralysis 100 mamp Ventricular fibrillation2000 mamp (2 amp) Ventricular standstill5 amp Electrical burn20 amp Blows common h/h fuse
ElectrocutionLow voltage
Burns usually present at entry/exit sites Caveat—current entering over broad surface, e.g.
bathtub electrocution
Death due to ventricular fibrillation
High voltageElectrical burns—chalky white with crateringCharring Death due to ventricular standstill or paralysis of respiratory center
ElectrocutionLightning
Direct strikeSide flashconduction
Death from high-voltage direct current
Usually due to burns and injury to respiratory center of brain
Gunshot Wounds
Gunshot Wounds
Mechanics of firingFiring pin ignition of primer ignition of gunpowder creation/expansion of gas bullet, unburned powder, soot propelled down barrel of gun
Gunshot Wounds
Entrance woundsContactClose rangeIntermediateDistant
Gunshot Wounds
ContactMuzzle imprintStellate lacerations (if adjacent to bony structure)Gunpowder and soot enters wound
Gunshot WoundsClose range—within 3 inches
Increase in distance = increase in diameter of particle deposition and tattooing around entrance wound and decrease in particle densityEntrance wound
Particles of gunpowder around wound Soot on skin Tattooing of skin
Gunshot Wounds
Intermediate range—3 to 36 inchesFurther increase in diameter of particle deposition and tattooing around entrance wound and further decrease in particle densityNo soot
Gunshot Wounds
Distant range—greater than 36 inches
Absence of gunpowder particles, soot, tattooingDifficult to determine exact distance—appearance of GSW inflicted at 6 feet doesn’t differ from one inflicted at 16 feet.
Gunshot WoundsEntrance wounds
Usually smaller than exit wounds unless:Located adjacent to bony structures
(stellate)Bullet deflected prior to entrance
Inward beveling of skullRim of abrasion
Gunshot WoundsExit Wounds
Usually larger than entrance wounds due to deflection of bullet by tissuesOutward beveling of skullNo gunpowder particles, soot, tattooingNo rim of abrasion
Shoring of exit
Gunshot WoundsShotgun Wounds
Contact—circular wound with muzzle imprintClose
Circular wound < 2 feet Scalloped edges at 3 feet Few stray pellets at 4 to 5 feet
Intermediate—6 to 7 feet Rim of pellets Wad abrasion
Distant—> 10 feet complete spread of pellets
Blunt Force Injuries
Blunt Force Injuries
Mechanism—tearing, shearing, crushingCategories
ContusionAbrasionLacerationfracture
Blunt Force InjuriesContusion—hemorrhage into the soft tissue surrounding the wound
No bruise if blow from wide/smooth object or in area protected by heavy clothes/hairPatterned
Steering wheel imprint on chest Parallel (train-track) lines from rod, stick, whip Horseshoe shaped—whipping with looped cord
Blunt Force InjuriesContusion
If death occurs quickly, no bruise evident—must incise area to detect hemorrhageColor change with time—from periphery to centerColor change may be used to “age” the injury—depends on size, extent, depth, local circulation
Immediately—slight swelling Few hours—light blue/red Week—dark purple > week—greenish-yellow
Blunt Force Injuries
ContusionVariables which increase bruising
Children and elderly • Senile ecchymoses on forearms of elderly
Obese women Alcoholics with cirrhosis Aspirin use
Blunt Force InjuriesContusions
Maybe be produced postmortem if severe blow delivered within a few hours of death
Rare Most common in skin/soft tissue overlying bone
Iatrogenic Surgical removal of corneas or globes Removal of vitreous
Blunt Force Injuries
Decomposed bodiesHemolysis of erythrocytes may mimic contusionsHemolysis of erythrocytes in genuine contusions also occurs—may be impossible to differentiate between decomp and contusion
Blunt Force Injuries
Abrasion—scraping/removal of superficial layers of skin
Graze—bulletScratch—fingernail, sharp edgeBrush burn—frictional force (dragging on ground)Binding—handcuffs/rope
Blunt Force Injuries
AbrasionPatterned
Weave of clothingThreaded pipeWood grain of baseball batgravel
Blunt Force InjuriesLaceration—blow from blunt objects or falls
Bridging of connective tissue within depths of woundAge determination difficultAppearance may not reflect object causing injuryIn general
Long, thin objects cause linear injury Flat objects cause irregular, ragged, Y-shaped injury
Blunt Force Injuries
LacerationExplore depths of wound for foreign materialDetermination of direction of wounding
abrasion/beveling—side from which blow delivered
Undermining of tissue—side away from which blow delivered
Blunt Force InjuriesFracture—direct or indirect force on bone
Direct Focal—small force applied to small area Crush—large force applied to large area Penetrating—large force applied to small area
Indirect—force acting at distance Traction—violent contraction of quadriceps m. Angulation—bending resulting in transverse fracture Rotational—twisting resulting in spiral fracture
Blunt Force InjuriesSkull fracture, base—usually run in direction of impact
Ring fracture—separation of rim of foramen magnum from remainder of base
Fall from height onto feet or buttocks
Transverse—side-to-side) Impact either side of head Side to side compression
Longitudinal—front to back Impact on forehead, face, back of head Front to back compression
Blunt Force Injuries
Skull fracture, baseBleeding from ears, nose or mouthHemorrhage into soft tissue of eyelids—raccoon eyesHemorrhage into soft tissue behind ears—Battle’s sign
Blunt Force InjuriesBrain contusion
Coup—occur at site of injury Blow to the head
Contrecoup—occur directly opposite to the point of impact
Classically associated with falls Frontal and temporal lobes Virtually never occur in occipital lobe
Blunt Force Injuries
Intracranial hematomaSubarachnoidEpiduralSubdural
Blunt Force Injuries
Subarachnoid hemorrhageMost common sequela of head traumaFocal or diffuseTraumatic
Laceration of veins—most common Laceration of internal carotid, vertebral,
basilar aa.
Blunt Force InjuriesEpidural hematoma—trauma to skull with rupture of artery at point of impact
Primarily impact injuries—falls, MVA’sBlood intervenes between dura and inner table skullA fracture is usually present—squamous-temporal bone
Blunt Force InjuriesEpidural hematoma
Usually confined to side of impactPresentation of symptoms
Usually 4-8 hours following injury Sometimes as soon as 30 minutes or as
late as 36 to 48 hours
Lucid interval prior to development of symptoms
Blunt Force Injuries
Epidural hematomaDeath due to displacement of brain (mass effect) with brain stem compression
Blunt Force InjuriesSubdural hematoma—acceleration/deceleration injury
Stretching/tearing of bridging veinsMost common lethal injury from head traumaUsually not associated with fracturesMay occur in absence of obvious sign of trauma
Blunt Force Injuries
Subdural hematomaAcute—symptomatic within 72 hrsSubacute—symptomatic between 3 days and 2-3 weeksChronic—symptomatic after 3 weeks
Blunt Force Injuries
Onset of symptoms usually acute (30 minutes)
Life threatening at 50 mlDisplacement of brain (mass effect) with brain stem compression
Blunt Force Injuries
Motor vehicle accidentsPatterned abrasions—steering wheelDicingSeat beltAortic transection distal to subclavian arteryFat embolism
Sharp Force Injuries
Sharp Force Injuries
Stab woundIncised woundChop woundTherapeutic/diagnostic wound
Sharp Force Injuries
Stab woundUsually homicideLength/depth of wound track > widthEdges usually without abrasion/contusion
Sharp Force InjuriesStab wound
Size and shape depends on many variables
Type of weapon—knife, ice pick, screwdriver
Configuration of weapon Direction Movement of blade in wound Langer’s lines—elastic fibers in skin
Appearance of wound margins depend on sharpness of knife
Sharp Force InjuriesStab wound
Determination of angle Oblique angle—beveled margin on one
side/undermining of skin opposite side
Determination of edgeSingle edge—squared off edge/sharp edgeDouble edge—both edges sharp
Sharp Force Injuries
Stab woundsMechanism of death
ExsanguinationTamponadeComplications (infection)
Sharp Force Injuries
Incised woundLonger than deepNo bridging (differentiate from laceration)Usually suicidal
Hesitation marks/scars
Usually not fatal
Sharp Force InjuriesHomicidal incised—neck
Inflicted from behindBegins high on neck opposite side
of cutting hand downward straight across midline upward, ending on opposite side of neck lower than initial point
wound first shallow, then deeper, then shallow
Sharp Force Injuries
Suicidal incised—neckInflicted from front
Short and angled Right handed—wounds on left side of
neck Slashes downward and medial at oblique
angle
Sharp Force Injuries
Chop woundIncised wound with underlying injury to boneIncised and lacerated characteristics
Cutting and crushing
Sharp Force Injuries
Chop woundAxeMacheteCleaverHoe
Sharp Force Injuries
Therapeutic/diagnostic woundssurgical stab wounds
Chest tube Abdominal drain Thoracotomy/lapartomy incisions Cutdowns of wrist/antecubital fossae, Tracheostomy incision