Forensic Pathology Flashcards
what is forensic pathology and what kinds of deaths are they involved?
applies principles and knowledge of medical science to problems of the law; violent (accident, suicide, homicide), suspicious, sudden and unexpected, deaths in an institution (prison, hospital <24 hours)
What are the major duties of the forensic pathologist?
cause and manner of death, ID deceased, determine time of death, collect evidence from body to prove/disprove, persons of guilt/innocence, document natural disease, determine contributory factors to death, provide testimony goes to trial.
Define cause of death. Examples.
injury/disease that produces physiological derangement resulting in death; gun shot wound, stab, coronary atherosclerosis
Define Mechanism of death. Examples.
physiological derangement produced by the cause of death; Hemorrhage, septicemia, cardiac arrhythmia
Define the manner of death. Examples.
natural, homicide, suicide, accident or undetermined. (can only be one of these five!)
What is a coroner?
elected individual who is not a physician, make ruling on cause and manner, no physician consult required, not required to order autopsy, not required to agree with autopsy findings, no training required
What is a medical examiner?
physician designated as medical examiner to determine cause and manner, can preform autopsies in cases that need them, established laboratory for use, 60% of country
How accurate is time of death generally? What major factors effect accuracy and ability to determine?
difficult and imprecise, often not possible, can only give a range majority of the time; as interval between time of death and discovery increase so does inaccuracy of estimation
what factors are used to estimate time of death?
livor mortis, rigor mortis, body temp, degree of decomposition, chemical changes in vitreous humor, stomach contents, insect activity, and scene markers (broken watch, unopened mail, piled up newspapers)
What is livor mortis?
reddish purple coloration due to settling of blood by gravity in dependent areas of body, onset 1/2 to 2 hours after death, max coloration 8-12 hours
What are some nuances in livor mortis that effect onset, or determination?
occasionally misinterpret as bruising, on firm surface may appear pale, may occurs prior to death in individuals dying of heart failure
what is the difference between shifting livor mortis and fixed livor mortis?
shift: intravascular pooling, can move from one area to another; fixed: blood hemolyzed and begins to diffuse into extravascular spaces, coloration won’t move
What is rigor mortis and general features of it?
stiffening of body after death due to postmortem muscle contraction, due to loss of ATP from muscle (stable actin-myosin complex preventing relax), onset 2-4 hours, fully developed 6-12 hours (jaw-> upper extremeties-> lower, order of onset and loss), lost due to decomp
what factors accelerate onset on rigor mortis?
violent exercise (deplete ATP), high body temp, hot weather (disappears less than 24 hours)
What factors cause rigor to persist?
temperate climate (36-48 hours), cold weather (persist several days)
What are the assumptions behind body temperature in determining time of death?
most common used method, based on everyone having a “normal” temp at time of death and body cools at uniform rate (both incorrect)
Why is the 1st assumption of temperature determination of time of death wrong (normal temp)?
normal: 96-100.8 F, diurnal variation- low at 6 am, high at 4-6, normal temp slightly higher in women, strenuous exercise and chronic disease can raise temperature
Why is the 2nd assumption of temperature determination of time of death wrong (uniform cooling)?
plateau where cooling does not appear to occur post mortem, body habitus influences cooling (fat insulates), infants cool quicker (mass/SA), ambient temperature effects, clothing, surface body is on (marble conducts heat, rug insulates)
How accurate is post mortem vitreous potassium levels in determining time of death and reasoning behind their use?
not valid; level of K determined by degree and rapidity of composition, accelerated decomp raises K levels (time only one factor in K levels)
Define autolysis. Example.
aseptic breakdown of tissue caused by intracellular enzyymes (pancreas)
Define Putrefaction.
breakdown of tissue due to bacteria, main cause of decomp, GI tract main source,
What are the visual clues of putrefaction?
green discoloration in abdominal quadrants or face and neck, swelling (gas production), protrusion of eyes and tongue, decomp fluid (red) from mouth and nose, slippage of skin with marbling (discoloration along vessels due to hemoglobin reacting to hydrogen sulfide) and blistering,, hair slip from scalp, internal organs and brains= porridge
What factor is a big contributor to putrefaction? Give Timelines for levels of decomposition.
accelerated by hot environment or sepsis; hot climate= 24hours, moderate 1-2 weeks, skeletonization- 1-2 weeks to months to years (climate dependent)
what are the features of cardiovascular disease in sudden natural death?
300-400K per year, leading natural cause men 20-65 years, if infarct unrecognized (uncharacteristic presentation) will rupture may occur presenting as sudden death (cardiac tamponade)
What are the statistical features of coronary artery disease in sudden natural death?
75% of all sudden deaths handled by MEs, 50% sudden death, 25% w/o preceding history or warning, Mechanism: usually lethal cardiac arrhythmia (80% ventricular, 20% sudden asystole)
What are the anatomic findings with coronary artery disease in sudden natural death?
severe coronary atherosclerosis (usually 2 vessels, LAD and or Left main, greater than 75% stenosis), myocardial scarring, infrequent findings: coronary artery thrombosis <15 and acute/sub acute MI
What are the features of hypertensive CVD in sudden natural death?
most cases accompanied by coronary artery atherosclerosis, cardiomegaly usually present, mechanism of death- acute cardiac arrhythmia (can be entirely from cardiomegaly)
What are the features of cardiomyopathy in sudden natural death?
characterized by myocardial dysfunction of known or unknown etiologies, not due to : arteriosclerosis, HTN, valvular, or infection; 3 categories: congestive or dilated, hypertrophic, or restrictive
what are the general features of CNS disorders as cause of sudden natural death? most common?
less common then cardiovascular; epilepsy, intracerebral hemorrhage, no-traumatic subarachnoid hemorrhage, meningitis, and undiagnosed brain tumor
What are the features of epilepsy as sudden natural death?
young, often in bed, complete autopsy generally negative, toxicology reveals absent or sub-therapeutic levels of anticonvulsants, bite wounds to tongue only 25% (can be associated with other death), Mechanism: cardiac arrhythmia, gross and microscopic changes in brain usually absent
what are the features of intracerebral hemorrhage in sudden natural death?
lead to sudden rapid death, 10-30% of all strokes, 45% caused by hypertension, other causes: amyloid angiopathy, AV malformation, tumors, bleeding diathesis, drug induced, and vasculitis, death= secondary brain stem compression/herniation or intraventricular hemorrhage
what are the features of cerebral infraction in sudden natural death?
less frequent cause of sudden death, less often in ME, less likely to cause death <24hours before diagnosis at hospital
what are the features of non-traumatic subarachnoid hemorrhage in sudden natural death?
rupture berry aneurysm (#1)- 90% silent til rupture, multiple in 15-20% of causes, 2/3 symptomatic btwn 40-60 yo, 1/3 symptomatic if younger, 80-90% in anterior portion circle of willis, fatal cases- 60% immediate and 80% of those survivors that will die < 24 hours
What is the occurrence of respiratory system causing natural sudden death? Main Pulmonary diseases behind it?
relatively infrequent ~10%; mainly: pulmonary thromboembolus, bronchial asthma, acute epiglottitis
What are causes of thrombolembolism that results in sudden death?
clot dislodged from lower extremity; blood stasis (immobility, obesity, intrapelvic tumors, and pregnancy), venous injury, and hypercoagulable disorder