Forensics Flashcards
What is the post-mortem interval?
The time between death and discovery.
Used to help find TOD.
What information can we use to estimate the TOD?
1) Changes in the body after death
2) Environmental and associated evidence
3) Anamnesic evidence (e.g normal routine/last known contact?)
What method is best for estimating TOD?
Core body temp.
It provides us with maximum precision within 95% confidence limits, (+/- 2.8hrs) during the first 24 hours after death.
What are the immediate changes that occur after death?
- No BP
- No O2
- Cardiorespiratory arrest
- Loss of neuronal activity (pupillary light and corneal reflexes)
- Muscle flaccidity (small twitches that decrease over time)
How to carry out a clinical examination when pronouncing death in a hospital?
Check ID tag Check pupillary light reflex Check respiratory rate Check heart sounds Check pulse Record TOD.
What are the early changes after death?
Rigor mortis
Livor mortis
Algor mortis
What is cadaveric spasm?
An intense immediate form of rigor that occurs during intense physical or emotional activity.
Describe the different form of lividity?
Cherry pink- CO poisoning.
Pink- Hypothermia.
Brick red- Cyanide poisoning.
Bronze- C. perfringens septicemia
When does lividity become fixed/non-blanching?
~12 hrs after death.
Why is lividity not good at determining TOD?
It has variable onset. Good for determining body positioning.
Is algor mortis immediate?
No, body temp stays normal for approx. 3.5 hrs after death.
Best areas to measure body temp for TOD estimate?
Rectum and Liver.
What are the late changes that occur after death?
Decomp. Entomology. Mummification. Adipocere. Skeletonisation. Animal scavenging.
What conditions/factors affect the rate of putrefaction?
Environment temp. Humidity Body build (Obese=Faster) Clothing Soil/pH/Moisture/Immersion in water. Systemic infection
What is casper’s rule?
States that decomp when immersed in water takes twice as long.
What is adipocere?
Type of decomp.
Occurs in damp/wet/immersion conditions.
Hydrogenation and hydrolysis of adipose tissue forming a waxy white substance.
Retains shape and outline of the face, body, and injuries.
What is mummification?
Type of decomp.
Occurs in dry/ low humid/ very hot (or extreme cold) environments with good airflow.
Drying of tissues and preservation of internal organs with leathery brown/black skin. Occurs in the place of putrefaction.
What is skeletonisation?
Type of decomp.
Climate dependent and assisted by animal activity.
Loss of soft tissues
What is entomology and why is it useful in determining PMI?
Entomology is the scientific study of insects in relation to other organisms, humans and the environment.
Forensic entomology is useful to determine PMI as insects arrive at the corpse in waves (different species at different stages of development found at different times.)
What is death?
The cessation of life in a previously viable organism. It is a process where cellular metabolic processes in different tissues cease at different rates.
What is somatic death?
Total failure of the body with irreversible loss of circulation, respiration and innervation and irreversible loss of consciousness.
What is cellular death?
The process of autolysis of cells postmortem, which occurs at different rates in different tissues.
What is brain death?
Cessation of function of the cortex, brain stem, or whole brain.
How to test for brain death?
- Absent pupillary light reflex
- Absent corneal reflex
- Absent motor response to painful stimuli on limbs
- Absent gag reflex and no cough reflex.
- Doll’s eye phenomenon
- Absent vestibulo-ocular reflex (negative caloric test).
- Persistent apnea when ventilator disconnected/no resp symptoms.
- Cerebral angiography and maybe EEG.
Tests should be carries out by two doctors, at least 5 years qualified and one must be a consultant.
Two sets 6 hrs apart (adult) or 12-48hrs apart (neonates).
Definition of a wound?
Disruption of the normal structure of tissues due to application of force.
Examples of blunt force injuries?
Bruises
Abrasions
Lacerations
Examples of sharp force injuries?
Incised/slash wounds
Stab wounds