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
What are the features of thromboembolism as sudden natural death? Mechanism of death?
usually in left main pulmonary artery, (if 60% blocked heart can’t pump); mechanical obstruction (large embolus), vasoconstriction due to vasospasm (multiple smaller emboli), pulmonary infarct <10% (due to dual vasculature)
What must be done during autopsy of PE is found?
attempt to locate origin (pelvic veins, incisions to popliteal fossae and posterior calves, usually no residual thrombi found
what are the features of bronchial asthma in sudden natural death?
~5% of all cases of chronic asthma, may occur w/o prolonged attack, increased frequency at night or early morning, triggers: allergens, infections, drugs (aspirin), psychological stress, exercise, and cold air
what is the mechanism of death with sudden death associated with bronchial asthma?
reduces flow with ventilation/perfusion mismatch resulting in decrease oxygenation of blood and increase CO2 and right ventricle overload, decreased airflow due to allergic release of histamine (vasoactive) causing bronchial contraction, marked intrabronchial mucus secretions
what is the mechanism of sudden death with acute epiglottitis?
marked edema of epiglottis and upper airway mucosa leading to mechanical obstruction, death can be rapid, most commonly H. influenza and S pneumonia (can follow pharyngeal exam with tongue depressor)
what are the various times of sudden death secondary to pregnancy complications?
uncommon due to prenatal care; 54.9% follow live birth, 7.7% while pregnant, 7.1% following still birth, 10.7% following ectopic pregnancy, 5.6% following abortion
What are the most common causes of death secondary to pregnancy complications?
ruptured ectopic (hemorrhage), embolism (PE more common than amniotic fluid embolism), pregnancy induced hypertensive complications (pre-eclampsia, eclampsia) and infection
What are the five categories of intraoperative deaths?
due to underlying disease, disruption of vital organ during procedure, air embolism, anesthetic related, can’t be ascertained
What are some examples of intraoperative death due to disruption of vital organ during procedure?
catheter passed through right atrium, rt. ventricle, or pulm artery perf; coronary artery perf;
When is an intraoperative air embolism death commonly seen?
CNS, laminectomy procedure
What are common causes of anesthetic related intraoperative deaths?
intubation of esophagus, administration of wrong gas, drug OD (most common), allergic reaction to iodine based dyes (rare), malignant hypertension (halogenated anesthetics and succinylcholine), most locals are cardiotoxic (arrhythmia)
what is an abrasion?
removal of superficial epidermis due to friction against rough surface
What is a contusion? Hematoma?
hemorrhage into soft tissue due to rupture of BV caused by blunt trauma (skin, lung, brain, heart, muscle); large focal collection of blood
How are contusions dated?
histo= not possible, color change= depth, pigment, location influence appearance and time of onset (superficial yellow sooner, eyes bruise immediately), evolution of color (hemoglobin degradation= varies by person and bruise, no standard terms
What is a laceration? What do you look for?
tear in tissue by shearing or crushing: internal organs and skin, blunt objects, falls, vehicle impact, skin irregular with abraded contusions, explore for foreign material from weapon or surface
What are the characteristics of a stab wound?
pointed instrument, wound tract depth exceeds skin length, sharp skin edges w/ or w/o contusion or laceration, single edge V pattern, secondary tract due to twisted knife or victim movement as knife pulled out
What are the characteristics of an incised wound?
cut produced by sharp edge weapon or incision, clean cut straight edge w/o abrasion or contusion, longer than deep, self inflicted= hesitation marks (superficial)
What are the characteristics of a chop wound?
heavy instrument with cutting edge, combo of incised and laceration (cutting and crushing) but mostly incised appearance
what is asphyxia? What are the non-specific classical signs?
failure of cells to receive or utilize O2; visceral congestion, petechiae, cyanosis
What is petechiae?
pinpoint hemorrhage produced by rupture of small vessels, sudden overt distension/rupture of vessels due to abrupt increase intravascular pressure= visceral pleura and epicardium, strangulation= conjunctiva or sclera, also caused by vomiting, coughing, and acute heart failure
What are the features of suffocation?
failure of O2 to reach blood (smothering-external airway obstruction, choking-internal airway obstruction, mechanical asphyxia- pressure outside body preventing respiration
What are the features of strangulation?
in all forms cerebral hypoxia secondary to compression of vessels supplying blood to brain; carotids- 11lbs pressure, unconscious 10 seconds, direct front pressure; vertebrals- severe lateral flexion or rotation (hanging) 66lbs pressure
How does hanging cause death?
asphyxia secondary to compression or constricture of neck structures by constricting band tightened by body weight, virtually all suicide, can obstruct airway but not necessary, rarely fracture neck
What are the features of hanging?
furrow in neck (not completely encircle, slants up to point of suspension), face pale, tongue protruding and black, blood pools in dependent areas (punctate hemorrhages or tardieu spots- black)
what effect does hanging have on internal structures of the neck? Other markers not always present?
50% no injury, 10-15% fracture of thyroid cartilage or hyoid bone; 25% have petechiae (absence due to complete arterial obstruction)
What are the general features of ligature strangulation?
pressure on neck applied by constricting band tightened by force other than body weight, virtually all homicides, mechanism the same as hanging
What are the physical features of ligature strangulation?
no complete occlusion of vasculature (vertebral open, veins compressed), face and neck congested, confluent sclera, conjuctival hem, 86% fine petechiae periorbital, horizontal ligature mark, rarely injure internal neck structures
How does manual strangulation occur and general features?
pressure from hand, arm, limb, compressing internal structures, virtually all homicide, mechanism of death the same, occlusion of airway minor role
what are the physical features of manual strangulation?
face congested and cyanotic, petechiae conjuctiva and sclerae, marks of violence- abrasion, contusion, fingernail marks, internal neck- extensive musculature hemorrhage, fracture hyoid/thyroid in older patients (more force than necessary)
What is SIDS?
sudden unexpected death of apparently healthy infant, less than 1 year, diagnosis of exclusion, examine scene, review of history, and complete postmortem fails to reveal cause of death
What are the demographics and “causes” of SIDS?
4-5K deaths per year, decreasing incidence, heterogenous group of disease, most 2-4 months and 92% <6 months, under 1 month- inability to adapt, peak- midnight and breakfast
what are increased risk factors for SIDS?
premature greater risk, males more than females, race not a factor, no known genetic etiology, temperature decrease (increase in SIDS)
what are the demographical features of child homicide?
in 07 322 bwtn 1-4 murdered, infanticide (killing <24 hours, usually mom, young and unmarried, usually smothered), after a few days of life usually blunt trauma, perpetrators more varied
What are the different types of child homicide?
classic battered child (neglected or starved), impulse or “Angry” homicide (majority), and “gentle” homicide (smothering or Munchausen by Proxy)
What is battered baby syndrome?
repeated intentional acts of trauma at slightest provocation, delay in bringing child to the hospital
How does battered baby syndrome present to the physician?
acute injury and old injuries, significant discrepancy between hx and clinical findings, explanation of trauma vague/inconsistent, head injuries from falling, burns, starvation (fussy eater), often severe diaper rash
What is seen on autopsy with battered baby syndrome?
multiple bruises various ages, pattern bruises, long incisions down back and buttocks, extremities to reveal soft tissue hemorrhage, most die from head trauma, retinal hemorrhage, punched in abdomen
What are the features of angry or impulse homicide?
most cases, sudden violent act brought on by trivial provocation, child picked up and thrown/slammed, may be well cared for
What are the features of gentle homicide?
smothering most commonly missed method, minor force necessary therefore no evidence of trauma, autopsy unremarkable, small percentage of SIDS (<10%)
What are the demographic features of Munchaussen’s by proxy?
usually mom, child brought to physician for induced signs and symptoms of illness, multiple hospital admissions, extensive evaluations or procedures all negative,
what are the methods for munchausen’s syndrome by proxy?
smothers child and then resuscitates or brings to ER semi-moribund, hx- apnea, cyanosis, loss of consciousness, continues to recur, extensive negative workup
What physical damage is seen with shaken baby syndrome?
retinal, subdural/subarachnoid hemorrhage caused by violent shaking (Peds), injuries to scalp and skull (contusions and fractures), impact trauma (
What are the actions that lead to shaken baby syndrome?
acceleration-deceleration traction stresses due to head whipping back and forth, original reports- diagnosis made clinically, autopsies not always performed
What is the damage seen with wound ballistics?
severity of wound- amount of tissue shredded base in KE lost by bullet in body, bullet enters tissue, imparts radial motion to tissue creating temporary cavity much larger than permanent
What happens when a gun goes off?
bullet, flame 1400 F, gas, soot, powder- burning or unbrunt, metal vaporized from bullet and jacket, primer compounds, copper and nickel vaporized from cartridge case
What are the features of a wound from a contact gunshot?
muzzle in contact with body, scorching of wound edges, soot deposited on wound margins, soot driven into wound tract, may be muzzle impression and soot on skin adjacent to wound
What are the features of a contact gunshot wound over bone?
stellate over entrance, soot deposited around bone entrance, , soot may be deposited on inner surface of skull, clothing may absorb soot and powder
What are the features of a near contact gun shot wound?
transition between contact and intermediate, entrance surrounded by wide band of seared blackened skin
What are the features of intermediate gun shot wounds?
powder tattooing, punctate abrasion of skin due to impact of unburnt and burning grains of powder in skin, range depends on gunpowder, barrel length caliber, size and density determine range, cant be wiped off
What are the features of distant gun shot wounds?
no soot or tattoing, cant determine exact range, entrance wound- abrasion ring, small, circle, or oval (reg. except over bone), can’t tell caliber based on entrance wound
What are the features of an exit wound?
larger and more irregular than entrance- bullet tumbling and deformation, no abrasion ring
What are the features of bullet wounds with a skull?
entrance- punched out with sharp edges, opposite surface beveled; exit- beveled or cratered outward
What are the differences in gun shot wounds with a high velocity riffle?
more KE means more wounding, external injuries to torso appear no different from handgun- severe internal injury, temporary cavity may fracture bone, injure vessels and organs far from bullet, micro tears, soft point hunting bullets- shed lead through body
What are some facts about suicides by gun?
5-6% rt handed shoot with left, multiple wounds does not rule out suicide, fatal accidental shooting while cleaning gun is usually not suicide, notes only 25%, blood on shooting hand 33-35%, gun in hand 25% hand and 20% long arm, occasionally shoot themselves in back of head
