What are “fouling” and “stippling”?
Fouling and stippling are terms used to describe the types of gunshot residue in close and intermediate range gunshot wounds. Fouling is the dust-like burnt powder grains that can be wiped off the body. Stippling (or tattooing) is from the unburnt powder striking the skin and causing a superficial injury. Stippling usually appears as numerous pinpoint injuries, and it cannot be wiped off.
Which can be wiped off the body, fouling or stippling?
Fouling and stippling are terms used to describe the types of gunshot residue in close and intermediate range gunshot wounds. Fouling can be wiped off, and stippling cannot.
A gunshot wound is classified as close range when there is fouling and stippling. Typically for a handgun, close range is within about (distance). Beyond that distance, the fouling will not reach the body but the stippling will. These wounds are classified as intermediate range.
A gunshot wound is classified as close range when there is fouling and stippling. Typically for a handgun, close range is within about 6” (15 cm). Beyond that distance, the fouling will not reach the body but the stippling will. These wounds are classified as intermediate range. If no fouling or stippling is observed, the term distant gunshot wound is used.
The wounding pattern produced by a shotgun will depend greatly on the range of fire. Under (distance), birdshot will cause a single round entrance wound that is 3/4 to 1” (1.5-2.5 cm) in diameter (regardless of the gauge of the shotgun). By a range of (distance), there will be a cookie-cutter pattern with scalloped margins as the pellets start to spread apart. At (distance), there are satellite wounds.
The wounding pattern produced by a shotgun will depend greatly on the range of fire. Under 2 feet, birdshot will cause a single round entrance wound that is 3/4 to 1” (1.5-2.5 cm) in diameter (regardless of the gauge of the shotgun). By a range of 2-3 feet (60 cm to 1 m), there will be a cookie-cutter pattern with scalloped margins as the pellets start to spread apart. At 4 feet (1.3 m), there are satellite wounds.
How accurate is estimating the range of fire of a shotgun based upon a radiograph of the pellets?
Not accurate; do not attempt. Due to the billard ball effect, shot will spread widely inside the body even though it may have entered the body through a single defect.
What is the classic location for trochar insertion for embalming?
Just superior and lateral to the umbilicus. And remember that diagnostic peritoneal lavage is usually done with a small midline incision.
By definition, a laceration is an injury due to ___.
By definition, a laceration is an injury due to blunt impact. The term is commonly misused in medicine to denote any skin injury that needs to be sutured. Sharp injuries (cuts, stabs) are not lacerations.
What type of wound may have features of both sharp and blunt injuries?
Chop wounds (such as from a hatchet).
What are the 3 types of blunt injuries?
Lacerations, contusions, and abrasions.
When a moving head impacts against a firm surface, the brain contusions are located (beneath/opposite) the point of impact. When a resting head is struck with an object, the contusions are located (beneath/opposite) the point of impact.
When a moving head impacts against a firm surface, the brain contusions are located opposite the point of impact. When a resting head is struck with an object, the contusions are located beneath the point of impact.
The dura is especially adherent to the inner calvaria in what ages?
The elderly and infants. This is why epidural hemorrhages are uncommon in these groups.
Why can blood from an epidural hemorrhage provide valuable toxicology information?
The epidural blood may contain valuable toxicology information particularly if the person survives for some time after the injury. Since it is relatively sequestered, the toxicology findings may best represent the state of intoxication at the time of injury as opposed to blood collected at autopsy which would have undergone normal metabolism during the interval of survival.
In intrauterine fetal death, how soon can maceration be seen?
Maceration may be seen at delivery in as early as 6 hours and almost always by 12 hours.
What are the half-lives of carbon monoxide in room air and in 100% oxygen?
Room air: 4-6 hours. 100% oxygen: ~1 hour.
Does heat cause epidural or subdural hematoma?
Heat can cause artifactual epidural hemorrhage but not subdural hemorrhage. A subdural hematoma found in a burned body occured before death.
What is the voltage threshold for low-voltage electrocution vs. high-voltage electrocution?
Do low-voltage and high-voltage electrocutions leave burns on the body?
Most high-voltage electrocutions will leave burns, but fewer than half of low-voltage electrocutions will leave burns.
Although the rate of rigor mortis is affected by various intrinsic and extrinsic factors, what is the general rule for the rate of progression?
Rigor mortis occurs gradually over several hours and usually reaches a peak (“full rigor”) in about 12 hours. Several hours later it will start gradually to disappear over the following 12 hours.
Although the rate of algor mortis is affected by various intrinsic and extrinsic factors, what is the general rule for the rate of progression?
Body temperature usually cools at a rate of 1-2 F per hour.
What percent of drownings will have “dry” lungs?
Hypothermia is defined as a core temperature of less than ___.
Hypothermia is defined as a core temperature of less than 95 F (35 C).
True or false: Most people with alcoholic cardiomyopathy have cirrhosis.
How is serum ethanol level converted to BAC?
To convert serum ethanol level to BAC, move the decimal point 3 places to the left. Example, a 100 mg/dL serum ethanol level is equivalent to a 0.10 (g/dL) BAC, or 0.10% (weight/volume). This means that one tenth of a percent of a person’s blood volume is alcohol or that a person has 1 part alcohol per 1000 parts blood.
Blood alcohol concentration in serum or plasma is __x higher than in whole blood.
Blood alcohol concentration in serum or plasma is 1.2x higher than in whole blood.
Where is ethanol mostly absorbed from in the body? How is it eliminated?
Ethanol is absorbed primarily in the small intestine and secondarily in the stomach. It is eliminated mostly by metabolism in the liver, with the remainder excreted through urine, exhaled breath, and sweat.
More than 90% of ethanol is oxidized in the liver primarily by what 2 enzymes? What are the metabolites?
Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). Metabolism at high alcohol concentrations follows zero order kinetics (independent of time and concentration of the drug). In the initial metabolic pathway, ADH breaks down alcohol into the toxic metabolite acetaldehyde. Small amounts of ADH are also found in other organs such as the stomach. This metabolite is further broken down to acetate by ALDH. Acetate is fed into the Krebs cycle and eventually broken down to water and carbon dioxide.
An estimate for blood alcohol level would be each ounce of whisky, 12 ounces of beer, or 5 ounces of wine raises blood alcohol level by ___ mg/dL. Peak is reached anywhere between ___ to ___ after the last drink. Metabolism is ___ mg/dL/hour and depends upon a multitude of factors.
An estimate for blood alcohol level would be each ounce of whisky, 12 ounces of beer, or 5 ounces of wine raises blood alcohol level by 15-25 mg/dL. Peak is reached anywhere between 30 minutes (if consumption in fasting state) to 3 hours after the last drink. Metabolism is anywhere from 10-30 mg/dL/hour and depends upon a multitude of factors.
How can IHC for beta-amyloid precursor protein be used in the evaluation of axonal injury?
Beta-amyloid precursor protein is a neuronal transmembrane glycoprotein that is transported by fast anterograde axoplasmic flow. In an uninjured brain, the protein is diffusely distributed in the axons and is not detected by the stain. In traumatic axonal injury, tearing or stress causes damage to the neuronal cytoskeleton and interrupts axonal transport. With axonal injury, the protein accumulates focally and can be detected by the IHC stain. Ischemic injury or traumatic axonal injury may result in accumulation of the protein, so anatomic location of the staining is important for interpretation.
Beta-amyloid precursor protein needs a survival interval of at least ___ to detect neuronal injury. Histochemical stains such as silver stain need survival intervals of at least ___ to detect injured neurons.
Beta-amyloid precursor protein needs a survival interval of at least 2 hours to detect neuronal injury. Histochemical stains such as silver stain need survival intervals of at least 12 hours to detect injured neurons.
Traumatic diffuse axonal injury is typically seen in what anatomic parts of the brain?
Corpus callosum, septum pellucidum, paraventricular areas, rostral pons.
What ages does SIDS affect?
Although the definition includes infants up to 1 year of age, one should be hesitant to certify a death as due to SIDS before 1 month of age or after 6 months of age.
Is SIDS heritable?
SIDS is a sporadic, nonheritable syndrome. A prior SIDS death in the same family should raise the suspicion of a genetic disorder (such as metabolic disease) or homicide.
What determines the gauge (“caliber”) of a shotgun?
The size of the wad. Shotgun cartridges (the shell containing the shot and the gunpowder) are sold in various gauges. A specific gauge shell can contain many different pellet sizes and numbers, but the wad will correspond to the gauge of the shotgun.
A shotgun wad can travel up to ___ feet and will usually enter the body if fired within a range of ___ feet.
A shotgun wad can travel up to 50 feet and will usually enter the body if fired within a range of 8-10 feet.
Commotio cordis is a sudden death due to a cardiac arrhythmia caused by a blunt impact to the chest. The impact must occur at what very narrow part of the cardiac cycle for the ventricular fibrillation to occur?
15 ms before the peak of the T-wave.
Analysis of postmortem glucose, enzymes, and drugs shows significant differences between specimens taken from the right side of the heart, the left side of the heart, and the peripheral blood vessels. ___ or ___ specimens best approximate the antemortem values.
Analysis of postmortem glucose, enzymes, and drugs shows significant differences between specimens taken from the right side of the heart, the left side of the heart, and the peripheral blood vessels. Peripheral venous or peripheral arterial specimens best approximate the antemortem values.
What are filter blots obtained from autopsy cases used for?
300 uL of blood may be spotted on specialized filter papers. Several samples can be collected, dried overnight, wrapped in plastic wrap, and stored at -20 C. Such samples are useful for genotype and protein analyses available through commercial and academic laboratories. An example would be using tandem mass spectrometry on postmortem blood spotted on filter paper to detect specific enzyme defects. Filter blots of liver tissue, bile, and vitreous humor may also be used.
What is the best fluid for postmortem chemical analysis?
Vitreous humor provides one of the best samples for postmortem chemical analysis because it comes from a closed space and postmortem values often approximate the antemortem levels. Vitrous humor may not become contaminated after embalming, so it may still provide material for analysis in these cases. However, a sample of the embalming fluid should also be submitted to the laboratory as a control.
Postmortem determination of premortem glucose levels. Discuss.
Postmortem serum glucose decreases rapidly because of glycolysis, preventing detection of antemortem hypoglycemia. Even elevated levels of postmortem blood glucose require careful interpretation. Death from asphyxia, cerebral hemorrhage, CHF, electrocution, or terminal CPR may increase postmortem peripheral vascular glucose and falsely indicate hyperglycemia. Glycosuria, ketonuria, or elevated serum acetone can help confirm diabetic ketoacidosis. Blood samples taken from the right atrium or IVC may have a high glucose content because of glycogenolysis in the liver and subsequent diffusion of glucose into adjacent vessels. Thus, a low glucose level in blood from the right atrium and a positive test for ketones may support starvation. Vitreous humor provides more reliable data for determination of antemortem hyperglycemia. Glycolysis reduces the postmortem concentration of vitreous humor glucose; however, values greater than 200 mg/dL usually indicate that the decedent had uncontrolled diabetes.
List the four general patterns of postmortem vitreous humor concentrations of sodium, chloride, potassium, and BUN/Cr, which allow some assessment of the terminal metabolic condition of the decedent.
Dehydration Pattern: Increased sodium and chloride concentrations. No significant increase in potassium. Moderate elevation of BUN/Cr levels. Uremic Pattern: No substantial increase in sodium, chloride, or potassium. BUN/Cr levels increased. Low-salt Pattern: Low sodium, chloride, and potassium concentrations. BUN/Cr stable. Decomposition Pattern: Low sodium and chloride concentrations. Increased potassium. BUN/Cr stable.
What is the most stable postmortem chemistry blood constituent?
Urea nitrogen is perhaps the most stable blood constituent after death as it approximates premortem levels even after moderate decomposition. Urea nitrogen also remains stable in CSF, vitreous humor (even after embalming), and synovial fluid. In addition to their use in assessing renal function, urea nitrogen concentrations aid in the interpretation of hypernatremia. Similarly, creatinine levels in the blood remain stable after death, as they do in CSF and vitreous humor, making creatinine a valid postmortem marker of nitrogen retention and renal function.
Metabolic acidosis can be categorized by presence or absence of anion gap. List causes from each category.
With increased AG (>12): ketoacidosis (diabetic, starvation, EtOH-associated), lactic acidosis, D-lactic acidosis, ingestions (methanol, ethylene glycol, diethylene glycol, propylene glycol, salicylate, toluene (if early or if kidney function is impaired)), pyroglutamic acid (5-oxoproline), CKD/uremia. With normal AG (<12): diarrhea or other intestinal losses, ureteral diversion, ketoacidosis posttreatment, carbonic anhydrase inhibitors, type 1 (distal) RTA, type 2 (proximal) RTA, type 4 RTA (hypoaldosteronism), toluene ingestion (if late and if renal function is preserved - dut to excretion of sodium and potassium hippurate in the urine), CKD and tubular dysfunction (but relatively preserved GFR).
How can toluene ingestion cause metabolic acidosis with increased anion gap in some cases and metabolic acidosis with normal anion gap in other cases?
Toluene ingestion causes increased AG if early after ingestion or if kidney function is impaired. It causes normal AG if late after ingestion and if renal function is preserved - due to excretion of sodium and potassium hippurate in the urine.
Elevated plasma osmolal gap can be seen with or without metabolic acidosis. List causes of each category.
With anion gap metabolic acidosis: ingestion (ethylene glycol, methanol, formaldehyde, paraldehyde); lactic acidosis; diabetic ketoacidosis; alcoholic ketoacidosis; end-stage CKD (GFR <10 mL/min) without regular dialysis. Without metabolic acidosis: ingestion (ethanol, isopropyl alcohol, diethyl ether); infusion of nonconductive glycine, sorbitol, or mannitol solutions; severe hyperproteinemia; severe hyperlipidemia.
Metabolic alkalosis can be categorized by chloride responsive (U Cl 10). List causes of each.
Chloride responsive: diuretic therapy, vomiting, NGT suction, villous adenoma, carbenicillin, contraction alkalosis. Chloride resistant: hyperaldosteronism, Cushing syndrome, exogenous steroids, licorice (glyccrhizic acid), Bartter syndrome, milk-alkali syndrome.
What is the equation for calculating volume of distribution?
Vd = D / C, where D is the quantity of an administered dose, and C is the resulting measured plasma concentration. A drug’s Vd is usually expressed in liters.
What are the T 1/2, T detectable, and key metabolites of the following drugs: cocaine, heroin, amphetamines, PCP, cannabis?
Cocaine: 1 hr, 24-72 hrs, benzoyl ecgonine methyl ester. Heroin: 3 min, 72 hrs, 6-acetyl morphine. Amphetamines: 30 min, 72 hrs, norepinephrine and phenylacetone. PCP: 30 min, 72 hrs, hydroxylated and glucuronated. Cannabis: 8 hrs, weeks, delta-9-THC-COOH.
Urine specimens may be suspicious for adulterants by color (blue tinge of toilet water), odor (such as bleach), and temperature (suspicious if cool). What values for pH, specific gravity, creatinine, and nitrite are suspicious for adulterants?
pH suspicious if less than 4.5 or greater than 8.0. Specific gravity suspicious for dilution if 500 ug/mL.
What is in the differential diagnosis of cocaine-associated chest pain?
MI (due to cocaine-induced vasoconstriction). Pneumothorax (due to inhalation barotraumas). Aortic dissection (due to HTN). PE (due to clotting activation). Endocarditis (due to injection of cocaine).
How are the specificities of myoglobin, CK-MB, and troponin I different in cocaine-induced AMI vs. non-cocaine-induced AMI?
Due to skeletal muscle effects, the specificity of both myoglobin and CK-MB is lower in cocaine-induced AMI, but the specificity of troponin I is equally good.
Propoxyphene is an opioid which, in addition to producing the usual opioid-related toxicities, can cause unusual toxicities, such as cardiac conduction abnormalities and seizures. Why?
Because both propoxyphene and its major metabolite (norpropoxyphene) cause a quinidine-like interference with sodium channels.
Phencyclidine (PCP). What are modes of delivery? What is the mechanism of action? Why are the behavioral manifestations characteristically fluctuating?
It can be ingested, injected, or smoked. It exerts its effects through blocking catecholamine re-uptake. The behavioral manifestations are characteristically fluctuating, thought to be a reflection of the marked lipid solubility of PCP, resulting in fluctuating blood levels.
Phencyclidine (PCP). What effects can be seen with intoxication, and with severe intoxication?
The effects of intoxication include hyperpnea, hypertension, and tachycardia. The behavioral manifestations fluctuate from periods of calm and sedation to periods of marked agitation, aggression, and incoordination. Horizontal nystagmus is often present and provides a clue to PCP use. Severe intoxication may present instead with hypoglycemia, hypotension, bradycardia, hypopnea, AMS, seizures, or life-threatening hyperthermia. Rhabdomyolysis may be induced by PCP. Leukocytosis is a frequent nonspecific finding.
What clinical effects do the following blood alcohol concentration %s produce: 0.4%?
0.4% - coma and death.
Alcohol testing in an overdose evaluation is usually based on serum or plasma. In forensic testing, either breath alcohol or whole blood alcohol is measured. Whole blood should be submitted in what tube and why?
Whole blood should be submitted in sodium fluoride and potassium oxalate to prevent both increases (due to fermentation) and decreases in ethanol concentration. Use of alcohol swabs on the venipuncture site should be avoided.
Blood alcohol can be measured in serum, plasma, or whole blood by an enzymatic procedure utilizing alcohol dehydrogenase. In addition to ethanol, what other alcohols does this method detect?
This method is fairly specific for ethanol and doesn’t measure other alcohols such as methanol.
What are the changes in postmortem chemistries for Na, Cl, K, and BUN/Cr for serum and vitreous?
Na: serum values decrease after death; vitreous values stable until onset of putrefaction. Cl: serum values decrease after death; vitreous values stable. K: serum and vitreous values increase after death. BUN/Cr: both serum and vitreous values are stable after death.
The CAP makes recommendations for the minimum requirements for the retention of laboratory records and materials. They meet or exceed the regulatory requirements specified in the Clinical Laboratory Improvement Amendments of 1988 (CLIA 88). For non-forensic autopsy, how long must the following be kept: wet tissue, paraffin blocks, slides, reports?
Wet tissue - 3 months after final report. Paraffin blocks - 10 yrs. Slides - 10 yrs. Reports - 10 yrs.
The CAP makes recommendations for the minimum requirements for the retention of laboratory records and materials. They meet or exceed the regulatory requirements specified in the Clinical Laboratory Improvement Amendments of 1988 (CLIA 88). For forensic autopsy, how long must the following be kept: wet stock tissue, paraffin blocks, slides, gross photographs/negatives, accession log, body fluids and tissues for toxicology, representative tissue suitable for DNA analysis?
Wet stock tissue - 1 yr. Paraffin blocks - indefinitely. Slides - indefinitely. Gross photographs/negatives - indefinitely. Accession log - indefinitely. Body fluids and tissues for toxicology - 1 yr. Representative tissue suitable for DNA analysis - indefinitely.