Forensic pathology

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Forensic pathology is figuring-out why people died... along with when and how (if possible).

Manner of death

 
 
 
 
 
 
 
 
Manner
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Homicide
 
Suicide
 
Natural
 
Accident
 
Undetermined

Notes:

  • Undetermined - is a waste basket category.
  • Homicide - not necessarily murder.
  • Can be group into three:
    1. Intent to kill (homicide, suicide).
    2. No intent to kill (natural, accidental).
    3. Undetermined.

Cause of death

General

  • The cause of death should be what started the sequence of events that lead to death.

"Word form"

Example:

  • C. difficle colitis complicating antibiotic treatment for a dental abscess.[1]
  • Complications of laparoscopic cholecystectomy for ascending choleangitis with mesothelioma and atherosclerotic heart disease.[2]

General forms:

  • A complicating B for the treatment of C.
  • A complicating B for the treatment of C with D and E.

WHO form

General form:[3]

  • 1a = immediate cause of death.
  • 1b = what lead to the immediate cause of death.
  • 1c... 1[x] -- where 'x' is the last letter used; 1x = What started the sequence of events.
  • 2 = contributing factors.

Example 1:

  • 1a. Ketoacidosis.
  • 1b. Diabetes mellitus.
  • 1c. Alcoholism.
  • 2. Acute bronchopneumonia.

Example 2:

  • 1a. Hemoperitoneum.
  • 1b. Splenic laceration.
  • 1c. Blunt force trauma.
  • 2. Liver cirrhosis.

Natural deaths

  • The cause should be a medical diagnosis, not the mechanism (e.g. cardiac arrest, cachexia, kidney failure).
  • The mechanism is irrelevant.

Notes:

Legal frame work

General

  • In Ontario, the manner is determined by the coroner.
  • Coroners, in Ontario, are MDs -- usually family docs.
  • The cause (e.g. "gunshot wound to the head") is determined by the pathologist.

NB - the word coroner is not synoymous with MD. British Columbia has coroners that aren't MDs.

Case classification (Ontario)

Cases are classified as:

  • A case = homicide and suspicious for homicide, (all) gunshot wounds.
  • B case = adult, non-suspicious.
  • C case = child, non-suspicious.

Notes:

  • All A cases are done at regional centers by certified forensic pathologists.

Forensic triangle

Most general differential diagnosis:

  • Natural:
    • Haemorrhage (e.g. cerebral bleed, gastrointestinal bleed, aortic aneurysm).
    • Infection (e.g. pneumonia).
    • Coronary atherosclerosis (cardiac arrhythmias - more common in the forensic context than myocardial infarction (MI); individuals with MIs don't usu. drop dead-- they go to the ER).
      • Post myocardial infarction (free wall rupture).
      • Ruptured (atherosclerotic) plaque.
  • Toxic (memory device: PAIRO):
    • Poisons.
    • Alcohol (EtOH).
    • Illicit (e.g. cocaine, heroin, LSD).
    • Rx.
    • Over-the-counter (OTC) (e.g. acetaminophen, warfarin).
  • Trauma (memory device AGE BS):
    • Asphyxial.
    • Gunshot wounds (GSWs).
    • Environmental (e.g. hypothermia, hyperthermia, drowning, lack of oxygen).
    • Blunt force trauma.
    • Sharp force trauma.

Difficulties arise when more than one point of the triangle is in play, i.e. the forensic pathologist has to earn their pay when an old man with a heart condition is known to be into erotic asphyxia, and dies after doing some drugs and whilst indulging in erotic asyphxiation with a friend...

  • If he had an arrhythmia and there was no stressor... natural death.
  • If he over did it with the drugs, it is an overdose, ergo accidental.
  • If he did the erotic asphyxia a bit too long it is accidental.
  • If the friend held the plastic bag over his head just a bit long to asphyxiate him... it is a homicide.
  • If he was a lone and depressed... he might have been trying to kill himself, ergo suicide.

Death-related changes

Rigor mortis

Def'n: muscle rigidity following death (caused by depletion of ATP).

Dependent on:

  • Temperature of patient at death.
  • Temperature variations in the environment since death.
  • Presence of some medical conditions.
  • May never develop!

Summary: Its onset & presence is highly variable. Therefore, it is only marginally useful for determining the time of death.

A crude guess for time of death based on rigor:[5]

  • Warm & flaccid <3 h.
  • Warm & stiff 3-8 h.
  • Cold & stiff 8-36 h.
  • Cold & flaccid > 36 h.

Notes:

  • Memory device: 3s: cut points are at 3 hours, 1/3 of a day, 3/2 of a day.

Livor mortis

Def'n: pooling of blood in the dependent position, due to blood stasis.

  • Onset may preceed death in the context of congestive heart failure.
  • If pressure is applied to a dependent area-- no blood can enter there; thus, a pressure area is blanched (i.e. white).
  • Can be seen externally, i.e. on the skin, and internally.
  • Liver mortis becomes fixed some time after death.
    • Liver mortis does NOT tell one the position the decedent was in at the time of death-- only the position the decedent was at the time liver mortis became fixed. If the decedent wasn't moved liver mortis can help determine the position the person was in when they died.

Decomposition

According to textbooks one of two things happens post-mortem:

  • Mummification, or
  • Putrefaction.

Real life:

  • A mix of mummification and putrefaction occur, i.e. part of the corpse is mummified... part of it decomposed through putrefaction.

Mummification:

  • Predominant in dry environments.
  • Body becomes dry and leathery.

Putrefaction:

  • Body wet/moist after death -- ideal environment for putrefactive bacteria and organisms.

Artefacts

  • Prinsloo and Gordon artefact = artefactual post-morten haemorrhage on the posterior surface of the esophagus.[6]

Classification of wounds

Mnemonic CALI:

  • Contusion - "bruise", haemotoma
  • Abrasion - "scrape", e.g. motorcyclist slide across the roadway... skin ripped-off
  • Laceration - "tear", trauma distant from where skin split
  • Incised - "cut", e.g. caused by a knife.[7]
    1. "Cut" or "slash" = length > depth.
    2. "Stab" = depth > length.

How to decide what you're looking at:

  • Contusion:
    • Can be demonstrated histologically... there are extravascular RBCs.
      • If pre-morten there is vital reaction, i.e. WBCs come to clean-up the trauma.
    • If the post mortem interval is not known and long-- differentiation from decomposition may be non-trivial/impossible.
  • Abrasion vs. contusion:
    • Contusions skin is intact... in abrasion it is not.
    • Abrasions and contusions may be co-localized, i.e. in the same place.
  • Laceration vs. incision:
    • Lacerations have "bridges", incisions do NOT have bridges.
      • Bridges are fine strands of tissue that cross the long axis of the skin defect.
        • You can think of the wound as partially "sutured" by the bridges of tissue.

Autopsy

Main article: Autopsy

The autopsy article covers procedural things. Heart dissection is covered in the heart article.

Types

Forensic vs. hospital:

  • Forensic autopsies are focused on the external exam.

Marking conventions for common findings

There are no universal marking conventions for injuries.

One system in use (the Rose system) is:[8]

  • One red line for an incised wound.
  • Multiple closely spaced red lines, i.e. red hatching, for abrasions.
  • Multiple closely-spaced blue lines, i.e. blue hatching, for contusions.

The above makes sense in that:

  • Abrasions and incised wounds typically bleed - are red.
  • Contusions (bruises) don't classically bleed and are classically blue.

External exam findings

Colour of the corpse:[9]

  • Red (Pink) = carbon monoxide, cyanide, fluoroacetate.[10]
  • Purple (intense) = propane.
  • Green = hydrogen sulfide.
  • Brown = nitrites (methemoglobinemia).

Autopsy terminology

  • Gutter butter = adipose tissue in a decomp case; looks like butter topping put on popcorn. A Toronto-ism.
  • Gutter blood = blood in the empty thorax - after extraction of the organ block.
  • Tardieu spots = postmortem hypostatic hemorrhages;[11] look like large petechiae - in dependent areas.

Causes of death

Gunshot wounds

Main article: Gunshot wounds

Gunshot wounds (GSWs) are a relatively uncommon finding in Canada. They are dealt within a separate article.

Asphyxia

Main article: Asphyxial deaths
  • This is a big topic and covered by a separate article.

Classification

  • Strangulation - where there are signs of neck compression.
    • Includes: ganging, ligature strangulation and manual strangulation.
  • Chemical asphyxia - usually no signs of neck compression.
    • Includes: carbon monoxide poisoning.
  • Suffocation - usually no signs of neck compression.
    • Includes: Smothering, choking, positional asphyxia, drowning.

Blunt force trauma

  • Pretty much anything.
  • Beer bottles are common... and strong enought to fracture a skull.
    • Empty bottles have a higher fracture energy than full ones.[12]

Commotio cordis

Features:[13][14]

  • Often negative autopsy; no cardiac pathology.
  • Etiology: arrhythmia.
  • History: trauma to chest.

Note:

  • May be spelled Commodio cordis.[15]

Trauma with delayed death

  • Epidural hemorrhage - lucid interval.
  • Subcapsular splenic hematoma with subsequent rupture.
  • Subcapsular hepatic hematoma with subsequent rupture.
  • Aortic dissection with subsequent rupture.

Sharp force trauma

  • Knife or other sharp object.

Aortic trauma

  • Aortic dissection due to trauma is often catastrophic.
  • Classic location of injury is subclavian branch point.[16]

Dissections often classified as:[17]

  • Type A - aortic root to just distal of left subclavian artery.
  • Type B - distal to (left) subclavian artery.

Head injuries

Diffuse axonal injury

Clinical:

  • Vegetative state. (???)
  • Imaging findings: no anatomical cause apparent in some cases. (???)

Etiology:

  • Hypothesized to arise from high shear loading of white mater tracts.[18]

Macroscopic findings:[18]

  • Tears - corpus callosum.
  • Haemorrhage.

Microscopic findings:[18]

  • Axonal retraction balls.
  • "Microglial stars".
  • Degeneration of fibre tracts.

Grading:

  • Grade 1: only microscopic findings.
  • Grade 2: ?
  • Grade 3: macroscopic and microscopic findings.

IHC: beta-amyloid precursor protein (beta-APP or APP).[19]

Intracranial hemorrhage

Main article: Intracranial hematoma

Classification:

  • Epidural hematoma.
  • Subdural hematoma.
  • Subarachnoid hematoma.

Traumatic brain injury in infants

Main article: Traumatic brain injury in infants
  • Shaken-impact syndrome.
  • Shaken baby syndrome.

Commotio medullaris

Features:[20]

  • Sudden death after head trauma that is insufficient to explain death.
  • Etiology: unknown - thought to be related to apnea.
  • Analogous to commotio cordis (see blunt force trauma).

Excited delirium

General:

  • Also known as "agitated delirium".[21]
  • Dx is considered controversial, especially outside of the forensic pathology community.[22]
  • The diagnosis has garnered considerable attention in the context of electroshock weapon use, as Taser International (a manufacturer of electroshock weapons) has blamed all deaths involving its weapons on it.
  • There is no "official" definition for excited delirium.
    • Most agree it includes fever.

One paper defines it in relation neuroleptic malignant syndrome:[21]

  • Fever.
  • Disorientation and confusion.
  • Increased energy/superhuman strength.

Excited delirium - hypothesis:

  • Thought to arise in the context of severe chronic mental disorders (e.g. schizophrenia) and protracted cocaine binges.[23]
  • Thought to result from alteration of dopamine receptor density. The D2 receptor in particular, which is thought to be important in temperature regulation, is decreased in psychotic cocaine abusers.[21]

Toxicology

Cocaine

  • No agreed upon toxic dose[24] - due to tolerance.

Features (see: cocaine toxicity):

  • Usually anatomically normal heart.
  • +/-Advanced atherosclerosis for age.
  • +/-Infarction.
  • +/-Contraction band necrosis.
  • +/-Cardiac hypertrophy.

Ethylene glycol

  • Not done in routine toxicology screening.
  • Birefringent calcium oxalate crystals found in kidney (with polarized light).[25]

Anaphylaxis

Serology:[26]

  • IgE.
  • Tryptase.

Natural death

Main article: Natural death

There is a lot that can kill ya... but only a few of those are quickly, i.e. within a hour or so.

Generally, these things are:

  • Cardiovascular:
  • Respiratory:
  • GI:
    • Haemorrhage.
      • Esophageal varices.
      • Gastric varices.
  • Neurologic:
    • Intracranial haemorrhage.
      • Ruptured aneurysm.
      • Spontaneous subdural haemorrhage.
    • Stroke:
      • Haemorrhagic.
      • Thrombotic (more common than haemorrhagic).

Forensic entomology

Main article: Forensic entomology
  • Study of the bugs that eat corpses.
  • Bugs may hide a wound... it is important to know where they like to be.

Forensic anthropology

Main article: Forensic anthropology

It is looking at skeletal remains. It may be useful of identification and, rarely, cause of death.

Forensic taphonomy

  • The study of post-mortem decay to assist in a medicolegal investigation.
    • Taphonomy = postmortem fate of biological remains; derived from the Greek word taphos (grave).[27]

See also

References

  1. ↑ MSP. 8 September 2010.
  2. ↑ TR. 3 September 2010.
  3. ↑ Pollanen MS (June 2005). "Deciding the cause of death after autopsy--revisited". J Clin Forensic Med 12 (3): 113–21. doi:10.1016/j.jcfm.2005.02.004. PMID 15914304.
  4. ↑ PS. 2009.
  5. ↑ Saukko, Pekka; Knight, Bernard (2004). Knight's Forensic Pathology (3rd ed.). A Hodder Arnold Publication. pp. 61. ISBN 978-0340760444.
  6. ↑ Piette MH, De Letter EA (November 2006). "Drowning: still a difficult autopsy diagnosis". Forensic Sci. Int. 163 (1-2): 1–9. doi:10.1016/j.forsciint.2004.10.027. PMID 16378701.
  7. ↑ DiMaio, Vincent J.M.; Dana, Suzanna E. (2006). Handbook of Forensic Pathology (2nd ed.). CRC Press. pp. 154. ISBN 978-0849392870.
  8. ↑ TR. 1 September 2010.
  9. ↑ Shkrum, Michael J.; Ramsay, David A. (2006). Forensic Pathology of Trauma: Common Problems for the Pathologist (1st ed.). Humana Press. pp. 33. ISBN 978-1588294586.
  10. ↑ Proudfoot AT, Bradberry SM, Vale JA (2006). "Sodium fluoroacetate poisoning". Toxicol Rev 25 (4): 213–9. PMID 17288493.
  11. ↑ Pollanen MS, Perera SD, Clutterbuck DJ (December 2009). "Hemorrhagic lividity of the neck: controlled induction of postmortem hypostatic hemorrhages". Am J Forensic Med Pathol 30 (4): 322–6. doi:10.1097/PAF.0b013e3181c17ec2. PMID 19901802.
  12. ↑ Bolliger SA, Ross S, Oesterhelweg L, Thali MJ, Kneubuehl BP (April 2009). "Are full or empty beer bottles sturdier and does their fracture-threshold suffice to break the human skull?". J Forensic Leg Med 16 (3): 138–42. doi:10.1016/j.jflm.2008.07.013. PMID 19239964.
  13. ↑ Kohl P, Nesbitt AD, Cooper PJ, Lei M (May 2001). "Sudden cardiac death by Commotio cordis: role of mechano-electric feedback". Cardiovasc. Res. 50 (2): 280–9. PMID 11334832.
  14. ↑ Maron BJ, Estes NA (March 2010). "Commotio cordis". N. Engl. J. Med. 362 (10): 917–27. doi:10.1056/NEJMra0910111. PMID 20220186. http://www.nejm.org/doi/full/10.1056/NEJMra0910111.
  15. ↑ Perron AD, Brady WJ, Erling BF (September 2001). "Commodio cordis: an underappreciated cause of sudden cardiac death in young patients: assessment and management in the ED". Am J Emerg Med 19 (5): 406–9. doi:10.1053/ajem.2001.24455. PMID 11555799.
  16. ↑ Kodali S, Jamieson WR, Leia-Stephens M, Miyagishima RT, Janusz MT, Tyers GF (November 1991). "Traumatic rupture of the thoracic aorta. A 20-year review: 1969-1989". Circulation 84 (5 Suppl): III40–6. PMID 1934437.
  17. ↑ Finkelmeier BA (September 1997). "Dissection of the aorta: a clinical update". J Vasc Nurs 15 (3): 88-93. PMID 9362838.
  18. ↑ 18.0 18.1 18.2 Blumbergs PC, Jones NR, North JB (July 1989). "Diffuse axonal injury in head trauma". J. Neurol. Neurosurg. Psychiatr. 52 (7): 838–41. PMC 1031929. PMID 2769276. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1031929/.
  19. ↑ Gleckman AM, Bell MD, Evans RJ, Smith TW (February 1999). "Diffuse axonal injury in infants with nonaccidental craniocerebral trauma: enhanced detection by beta-amyloid precursor protein immunohistochemical staining". Arch. Pathol. Lab. Med. 123 (2): 146–51. PMID 10050789.
  20. ↑ Shkrum, Michael J.; Ramsay, David A. (2006). Forensic Pathology of Trauma: Common Problems for the Pathologist (1st ed.). Humana Press. pp. 613. ISBN 978-1588294586.
  21. ↑ 21.0 21.1 21.2 Wetli CV, Mash D, Karch SB (July 1996). "Cocaine-associated agitated delirium and the neuroleptic malignant syndrome". Am J Emerg Med 14 (4): 425–8. PMID 8768172.
  22. ↑ http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2374865
  23. ↑ Pollanen, MS.; Chiasson, DA.; Cairns, JT.; Young, JG. (Jun 1998). "Unexpected death related to restraint for excited delirium: a retrospective study of deaths in police custody and in the community.". CMAJ 158 (12): 1603-7. PMC 1229410. PMID 9645173. http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1229410.
  24. ↑ Stephens BG, Jentzen JM, Karch S, Wetli CV, Mash DC (March 2004). "National Association of Medical Examiners position paper on the certification of cocaine-related deaths". Am J Forensic Med Pathol 25 (1): 11–3. PMID 15075681.
  25. ↑ Saukko, Pekka; Knight, Bernard (2004). Knight's Forensic Pathology (3rd ed.). A Hodder Arnold Publication. pp. 589. ISBN 978-0340760444.
  26. ↑ Simons FE (February 2010). "Anaphylaxis". J. Allergy Clin. Immunol. 125 (2 Suppl 2): S161–81. doi:10.1016/j.jaci.2009.12.981. PMID 20176258.
  27. ↑ Milroy CM (August 1999). "Forensic taphonomy: the postmortem fate of human remains". BMJ 319 (7207): 458. PMC 1127062. PMID 10445946. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1127062/.

External links

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