Forensics autopsy Flashcards
what is hypostasis?
sedimentation and diffusion of red cells and plasma after death (pale at areas of support)
what is rigor mortis and what affects it?
linking of actin and myosin in absence of ATP
slower if cold, faster if warm
faster if physical exertion before death (less ATP available)
timing of death by temp and rigor (nb for spot assessment, not legal!)
warm + flaccid: <3 hrs
warm and stiff: 3-8 hrs
cold and stiff: 8-36 hrs
cold and flaccid: >36 hrs
types of decomposition (4)
putrefaction (discolouration, gas buildup, skin slippage etc)
mummification (dry decomp)
conversion to adipocere
maceration (in fetuses)
considerations in decomposition
insect activity
internal organs often better preserved than external suggests
slower decomp in water
cooling affected by…
initial body temp
body size
posture
clothing/covering
ambient temp/humidity
air movement
medium around body
hemorrhage
ways to identify a body
face
eye colour
skin colour
hair colour/structure
tattoos, scars
fingerprints
stature
sex
DNA (esp blood, spleen, muscle, bone marrow)
types of wounds
abrasion: superficial injury by blunt force or scraping
laceration: full thickness tearing injury by blunt force
incised wound: cut injury longer than deep
stab wound: cut injury deeper than long
bruise/contusion: extravascular blood under intact skin due to trauma
ecchymosis: extravascular blood under intact skin not due to trauma
common patterns of injury
tyre marks
fingers
tile pattern
laceration vs incision
laceration:
bruise and crush at edge
tissue strands across wound
no corresponding line in underlying tissue or overlying clothes
sudden death, think of…
cardiac
vascular (aortic or brain aneurysm, PE)
epilepsy
lungs (asthma, obstruction)
GI (haemorrhage, acute abdomen)
poison
suspicious
post-op death - categories to think of (4)
death from disease for which surgery perforemd
death due to other disease
death due to surgical technique
death due to anaesthetic (incl malignant hyperthermia)
approach to post-op death
clinical history and sequence of events essential!
ideally have surgeon or anesthetist present at autopsy
look for anaesthetic and surgical devices in situ (eg intubation)
Driver injuries in MVA
leg/knee against dash
leg# or hip dislocation against floor
abdo/chest against sterring wheel (look for internal injury)
face/head through windscreen
hyperflexion cervical spine (esp C5/6)
aortic rupture
impact on road/other cars
penetrating injury
pedestrian injuries in MVA
(acceleration rather than deceleration)
knees/shins against bumper
head/other injures against road/car
runover
identifying injuries (tyres, paint, glass)
MVA autopsy, think of… (2)
natural disease
toxicology (drugs and alcohol)
considerations for drowning autopsy (5)
may have:
- drowned (why in? why didn’t get out?)
- died disease/injury and fell in water
- died disease/injury and thrown in water
- died of disease/injury while in water
- died of effects of immersion (eg vasovagal, larygnospasm)
autopsy findings of drowning (nb: none are specific!)
history: scene info (tides, hazards etc), circumstance
external: plume, eardrum perf, tongue biting, injuries, immersion
internal: pleural effusion, hyperinflated lungs, subpleural haemorrhage
types of asphyxia (= struggle to breathe against mechanical interference)
- suffocation: obstruction external orifices (look for defence marks)
- choking: obstruction of upper airways (usu food +/- neuro impaired)
- hanging: ligature using weight of body
- strangulation: constriction other than weight of body
- crush: external copression of chest (usu accidental)
- positional asphyxia: upside down, neck flexion etc
autopsy findings choking
petechiae if retching
buccal mucosa damage
pulmonary oedema
autopsy findings hanging
scene exam important
ligature: above thyroid prominence, pattern, deepest opposite point of suspension, investigate stratches
petechiae (not present if carotids completely occluded!)
autopsy finding strangulation
ligature or manual: below thyroid prominence
prominent petechiae
neck dissection for bruising
hyoid and thyroid cartilage #
look for other injuries and sexual assault
toxicology - antemortem considerations
dose and time
route
tolerance
?steady state (or increasing/decreasing)
toxicology - postmortem considerations
- sampling site: central blood and urine (for screening), peripheral blood (for quantification), vitreous (esp heroin, alcohol)
- interval between death and sampling (bacteria and metabolism)
- sequestered compounds (can leach out of fat/organs even though none in blood antemortem)
- vitreous for beta-hydroxybutyrate (eg alc ketoacidosis)
medical conditions affecting or affected by toxicology (5)
heart disease: illicit drugs lower arrythmia threshold
renal disease: excretion rates
liver disease: less drug binding protein
lung disease: susceptible to CNS depressant and alcohol
CNS: susceptible to seizures
Systemic findings - alcoholism
CNS: Wernickes, executive function, respiratory centre
dilated cardiomyopathy
liver: hepatitis, cirrhosis, fatty liver
pancreatitis
GI: gastritis, varices, ulcers
fetal alcohol syndrome
cancer (vis aldehydes)
Systemic findings - hypertension
renal failure/nephrosclerosis
hypertensive cardiomyopathy (hypertrophy)
atherosclerosis
dissection
cerebral haemorrhage (CVA or dementia)
Systemic findings - diabetes
macrovascular disease:
atherosclerosis (via endothelial dysfunction) - MI and stroke
gangrene lower extemities
hyaline arteriosclerosis
microvascular disease:
nephropathy (glomerular, atherosclerosis and pyelonephritis)
retinopathy
neuropathy
also: infections (pneumonia, skin, kidney), ketoacidosis (check vitreous)
