Mazzariol - PMI Flashcards
(98 cards)
What is the Decomposition Condition Code (DCC)?
The DCC is a classification system used to evaluate the state of decomposition of animal carcasses, particularly cetaceans and sea turtles. It assigns numerical codes from 1 to 5 to indicate levels of preservation or decomposition.
What characterizes a Code 1 carcass in the DCC?
Code 1 represents an extremely fresh carcass. Features include:
* Recently dead, often live-stranded and euthanized cases
* No post-mortem changes such as bloating or skin sloughing
* Clear, glassy eyes; firm and white blubber; muscles dark red and well-defined
* Organs and brain intact and easily distinguishable.
What defines a Code 2 carcass in the DCC?
Code 2 signifies a fresh carcass with minimal decomposition:
* Slight drying or wrinkling of skin and mucous membranes
* Eyes and tongue may appear normal or only slightly sunken
* No bloating; blubber firm and sometimes blood-tinged.
What does a Code 3 classification indicate?
Code 3 denotes moderate decomposition:
* Visible bloating with possible protrusion of tongue and penis
* Skin sloughing and mild characteristic odor
* Organs are intact but softer; brain consistency is reduced
* Blood appears thin and black.
Describe the features of a Code 4 carcass in the DCC.
Code 4 represents advanced decomposition
- Carcass may collapse with significant skin sloughing
- Strong odor; muscles liquefied and viscera friable
- Brain dark red, liquefied, and may contain gas pockets.
What is a Code 5 classification in the DCC?
Code 5 refers to a mummified or skeletal remains carcass
- Skin may drape over bones
- Remaining tissues are desiccated
- Organs are partially or completely absent.
Why is the DCC important in post-mortem investigations?
The DCC guides sample collection and helps assess the reliability of histology, microbiology, and toxicology analyses based on the decomposition stage.
What are the key steps in tissue sampling during post-mortem investigations?
Steps include:
- Identify the organ or tissue of interest
- Collect samples using sterile instruments to avoid contamination
- Store samples appropriately (e.g., formalin for histology, freezing for microbiology or toxicology)
- Label samples clearly with collection details.
What tissues are sampled for histopathology?
Tissues include:
* Skin
* Blubber
* Internal organs (liver, lungs, kidneys, heart)
* Central nervous system (brain, spinal cord).
What is the purpose of collecting tissue for toxicology?
Toxicology samples help detect:
* Heavy metals (e.g., mercury, lead)
* Persistent organic pollutants (POPs) like PCBs and DDT
* Biotoxins such as domoic acid.
Which storage methods are recommended for microbiological samples?
Recommended methods include:
* Samples should be stored in sterile containers
* Maintain samples at cool temperatures (e.g., ice packs or refrigeration) if immediate processing isn’t possible
* Use cryopreservation for long-term storage.
What are common diagnostic tools used in virology investigations?
Common tools include:
* PCR and RT-PCR for viral RNA/DNA detection
* Viral culture for pathogen growth and identification
* Immunohistochemistry for locating viral antigens in tissues.
What is the role of gross examination in post-mortem analysis?
Gross examination provides an initial assessment of:
* External and internal anatomical abnormalities
* Signs of trauma or disease
* General condition (e.g., nutritional state, organ integrity).
Why is histopathology critical in PMIs?
Histopathology identifies microscopic cellular changes that reveal:
* Disease processes
* Infections or inflammations
* Tumors or toxic effects.
How does the Nutritional Condition Code (NCC) complement DCC?
The NCC evaluates an animal’s health prior to death based on fat reserves, muscle mass, and external appearance.
What diagnostic techniques are used to identify parasitic infections?
Techniques include:
* Microscopic examination of tissues for larval or adult parasites
* PCR for detecting parasitic DNA
* Morphological identification of external parasites (e.g., ectoparasites).
What is Virtopsy, and why is it used?
Virtopsy refers to a virtual autopsy using imaging techniques like CT or MRI. It’s non-invasive and useful for:
* Studying skeletal injuries
* Detecting internal abnormalities without dissection.
What is the utility of diatoms in determining drowning as a cause of death?
Diatoms are found in the bloodstream and organs when drowning occurs in water containing these microorganisms.
What role do forensic entomology studies play in PMI?
Forensic entomology involves studying insect activity on carcasses to estimate time since death or decomposition stage.
What are the critical considerations for gastrointestinal tract sampling?
Considerations include:
* Ensure sterile collection methods to avoid contamination
* Note the presence of foreign objects, parasites, or lesions
* Segment the tract for microbiology, toxicology, and histology tests.
How are brain samples handled during a PMI?
Brain tissue is removed intact when possible, fresh samples are frozen or preserved in formalin, and sections are taken for histopathology and virology analysis.
What considerations are important for skeletal system examination?
Important considerations include:
* Assess fractures, deformations, or signs of disease
* Collect bone samples for DNA analysis or age estimation
* Use imaging techniques like X-rays or CT scans for internal inspection.
Why is blubber sampling significant in toxicology?
Blubber acts as a storage site for lipophilic toxins like PCBs and DDT, providing insights into long-term pollutant exposure.
How should blubber thickness be measured during a post-mortem investigation?
Measure at standardized anatomical locations (e.g., dorsal midline, cranial to the dorsal fin), use a caliper for precise measurement, and record depth in millimeters to indicate nutritional status.