Post mortem examination Flashcards
What is a post mortem/ necropsy/autopsy?
- the examination of a body after death
We perform PME to confirm or refute a clinical diagnosis - what would this include?
- if the diagnosis was correct
- can you reined the differential diagnosis
- was there other concurrent disease
We perform PME to work out if there was failure in treatment - why do we do this?
- to work out why did treatment of clinical diagnosis fail
- clinical audit
What is sudden death?
- death without any knowledge of disease, injury or intoxication, or death within minutes or hours of onset of clinical signs
Why do we perform a PME for sudden death?
- aims to provide a diagnosis when there is no clinical diagnosis
What is apparent sudden death?
- the clinical signs had not been noticed by owner
- e.g., prey animal masking evidence or suffering
Why do we PME in herd, group or population health?
- for rapid diagnosis of disease in a herd, group or population
- provides additional opportunity to implement treatment, nutrition or management changes to prevent further losses of individuals or production
How do we use PME in surveillance?
- monitor endemic disease
- detect exotic / notifiable disease
- monitoring effects of husbandry / management changes
- public health
Forensic post mortem examinations can be used in cases of crime involving animals - what do these look into?
- cause of death
- disease / health status
- degree of suffering
- obtaining trace evidence
- identification
- insurance
- malpractice inquests
Zoo animals have PME following death or euthanasia - why may these be performed?
- population health
- research
- husbandry / management changes
What can obtained samples be used in?
- histopathology
- microbiology
- bacteriology
- virology
- mycology
- parasitology
- trace element analysis
- toxicology
PME can be used in research such as toxicological pathology - what can tissues/other samples for further study be used in?
- pathology research
- clinical research
- basic science research
- achieved samples allow retrospective studies
There is no one correct way to perform a PME - however what should you make sure you do?
- examine every organ
- follow a standard procedure
- take samples from each tissue into formalin (1:10)
- take any additional samples which may require for further testing
What prerequisites are required before a PME?
- permission to perform
- reason to perform
- signalment (species, breed, sex, age)
- clinical history
- time of death
- mode of death
- found death
- type of euthanasia
- cadaver storage
What should be checked before PME?
- check identification details compared to paperwork
- packaging and any other items
- microchip number
- body weight
- crown to rump length/height
During an external examination pre PME why do you not give a BCS?
- dehydration and post mortem changes of the cadaver, and lack of muscle tone can give a misleading score
What should be described in a post mortem examination?
- subcutaneous adipose tissue
- adipose tissue: around organs, behind eyes, in marrow cavities
- muscle and organ size/atrophy
- bony prominences
What descriptors can be used to describe each point in a PME?
- excellent, adequate through to emaciated
What would you like for on the external examination?
- wounds or other superficial lesions
- hair coat condition, ectoparasites
- discharges from orifices
- colour of skin, sclera and mucous membranes
How would you perform the initial dissection?
- disarticulate the limbs to ensure cadaver is stable
- midline skin incision (through skin only) from mandibular symphysis to pubis
- reflect the skin way from the midline to expose subcutaneous tissue to muscle
What would you look for in skin and subcutaneous tissues?
- colour changes
- masses
- fluid
- gas
What would yellowed skin or tissues indicate?
- icterus
What would pallor skin or tissues indicate?
- loss of blood / anaemia
What would red-purple skin or tissues indicate?
- congestion, sepsis, bruising
What would green skin or tissues indicate?
- bile imbibition, pseudomelanosis
What would gelatinous skin or tissues indicate?
- oedema, serous atrophy of fat
How would you open the adnominal cavity during an PME?
- incise along linear alba (avoid viscera, top right image)
- collect any fluid within the abdominal cavity
- cut from Linea alba laterally along the last rib on each side to open the cavity
- check for negative pressure in the thoracic cavity (small incision in diaphragm)
- check topography
How would you open the thoracic cavity in a PME?
- cut along the costochondral junctions on one sider of the thorax
- reflect the rib cage (dethatching the mediastinum)
- cut along the bend in the costochondral junctions on the other side to expose the thoracic contents
What is the pluck?
= tongue, larynx, thyroid and parathyroid glands, trachea, oesophagus, heart and lungs
How would you remove the pluck?
- cut along the medial aspect of the body of the mandible, from the ramus to the symphysis, bilaterally
- reflect the tongue, ventrally, through incision
- hold the tongue and move ventrally and caudally
- examine the hyoid apparatus before cutting through the cartilaginous joints
- continue reflecting ventrally and caudally the tongue, larynx, trachea and oesophagus by cutting the fascia dorsal to these structures
- continue this technique to remove the heart and lungs still attached to the pluck
- cut oesophagus, vena cava and aorta at the level of the diaphragm to remove the pluck from the cadaver
How would you check patency of the bile duct?
- make a small incision into the duodenum, near the bile duct
- squeeze the gall bladder
- bile should ooze from the incision
What would you then remove from the abdomen (after removing viscera)?
- remove the adrenal glands
- remove the liver and spleen
- remove the GIT
- remove the urinary tract
- remove ovaries and uterus/testes
What extra things would you check after dissecting from the abdomen?
- check lymph nodes
- check bones and joints
How would you examine the oesophagus in the pluck?
- remove the thyroid and parathyroid glands
- open the oesophagus
- examine content
- are there strictures (narrower bits)
- are there lesions
How would you examine the larynx, trachea and bronchi of the pluck?
- with clean scissors open the larynx, trachea and bronchi
- check content
- check for froth
- check for lesions
When examining the heart what should you make sure to do?
- examine every chamber
- examine every valve
What should heart weight be in cats and dogs?
- dogs = <1% of body weight
- cats = <18-20g
The thickness of left ventricular free wall, interventricular septum and right ventricular free wall should be a ratio of what?
- ratio of 3:3:1
What components of the heart should you examine?
- pericardium
- epicardium
- myocardium
- endocardium
- valves
How would you examine the parenchymatous (liver, spleen, lungs) organs?
- make a partial thickness incisions through parenchymatous organs
When removing the capsule from the kidneys what would you look for?
- adhesions
- lesions
- exudate
You would then bisect the kidneys to examine what?
- cortex
- medulla
- pelvis
- urethra
What would you collect from the urogenital tract?
- urine if possible
Apart form the kidneys what other aspects of the urogenital tract would you open and examine?
- bladder
- genital tract
- reproductive organs
What would you do when examining the entire GIT?
- collect and describe stomach and intestinal contents
- examine the serosa and mucosal surfaces
How would you examine the central nervous system?
- remove head
- check foramen magnum - open cranial vault
- check meninges - remove brain and eyes ( +/- spinal cord)
- fix whole before dissection ( around 1 week)
When would you need to describe lesions?
- PME
- biopsy submissions
- clinical consultation notes
- surgery reports
- referral letters
- seeking advice from pathologist/other vets
What descriptors would you use to describe a lesion?
- organ/tissue
- position
- number
- weight
- distribution
- contour
- size
- colour
- shape
- consistency
- smell
When taking about the weight of a lesion what do you need to include?
- percentage of body weight
What does distribution of a lesion refer to?
- the spatial arrangement of lesions within the tissue
You can describe a lesion as random distribution - what does this mean?
- without relationship to the architecture of the organ or tissue
- e.g., abscess or tumours in the lungs or liver
What does symmetrical distribution mean?
- highlights or outlines an anatomical or physiological subunit
- e.g., metabolic disorder affecting a group of related cells in a paired organ
What does focal distribution mean?
- a single defined lesion on a normal background or background exhibiting a different process
- e.g., an abscess in a consolidated lung
What does multifocal distribution mean?
- more than one discrete lesion on a background
What is multifocal to coalescing distribution?
- many lesions which appear to be growing together or fusing suggesting an active process which is expanding or not contained
What is miliary distribution?
- numerous tiny foci which are too numerous to count
What is a segmental distribution?
- well defined portion of the tissue is abnormal
- often defines a vascular bed
What is a diffuse lesion?
- the whole tissue is affected
What is a raised contour and give examples?
- where something is added
- fluids = blood, transudate, exudate, effusion, oedema
- cells = hyperplasia, neoplasia, inflammation
- tissues = fat, cartilage, bone
What is a depressed contour and give examples?
- something has been removed
- necrosis
- atrophy
How would you describe a flat contour?
- not raised or depressed
- has not had time to progress or does not cause expansion or necrosis
How do we measure lesions?
- in 3D
What would a uniform size lesion be like?
- lesions occurring at the same time, or over a short period, and are progressing at the same rate
What would a non-uniform lesion be like?
- lesions are separated in time or rate of progression
Organs could be larger than normal due to what?
- hyperplasia
- hypertrophy
- oedema
- neoplasia
- congestion
- inflammation
Organs could be smaller than normal due to what?
- hypoplasia
- atrophy
- necrosis
What does dynamic organs mean?
- size due to physiological status
What organs would be rapidly (sec-mins) dynamic?
- lungs, urinary bladder
What organs would be moderately dynamic (min to hrs)?
- spleen, GIT, brain
What organs are slowly dynamic (days to months)?
- heart
- liver
- lymph nodes
- endocrine glands
What would a red to red black colour suggest?
- congestion
- haemorrhage
What would a white/grey/yellow colour suggest?
- lack of blood, necrosis, icterus, fibrosis
What would a black colour suggest?
- melanin
- melanosis - flat
- melanoma - raised
What would a green-black colour suggest?
- pseudomelanosis
- H2S pigments
What would a green colour suggest?
- bile
- some fungi
What do you need to think of when describing lesion shape?
- what does it most resemble
- 2D or 3D terms
- symmetrical shapes and pattern may reflect the underlying architecture
What would a gas consistency be like?
- trapped in tissue
= emphysema
= autolysis
What would a fluid consistency be like?
- looks or feels wet
= oedema
= blood
= transudates
= fluid rich exudate
= effusions
= urine
What would a soft consistency be like?
- fluid rich
- cell/stroma poor
What would a firm consistency be like?
- fluid poor
- cell/stroma rich
What would a hard/gritty consistency be like?
- mineralised stroma/matrix
- cartilage
- bone
- calcified tissue
If a lesion has a distinct smell what could theses be?
- Foul = rotting smell, putrefactive necrosis, saprophytic bacteria
- Ammonia = uraemia
- No odour = aseptic process?
If a lesion has a distinctive sound what could these be and what could they mean?
- Crepitant – emphysema, gas producing bacteria, normal lung (absence = atelectasis)
- Sloshing – fluid filled structure – ascites, effusions, diarrhoea
