Postmortem Changes

Lecture 6

Postmortem changes are the result of what?

autolysis (decomposition)

Are postmortem changes a pathologic process?

No

Since postmortem changes are not a pathologic process, are there lesions?

No

Antemortem changes occur when?

prior to death

Antemortem changes take how long to develop?

minutes to hours to weeks

What is autolysis?

the decomposition of cells which occurs due to loss of cellular integrity or breakdown of cells which occurs after death

How do we minimize autolysis?

by performing a post mortem evaluation and collection of tissues as close to the time of death as possible

Fixing tissues in a fixative such as formalin at the time of collection will do what?

halt autolysis

How do fixatives halt autolysis?

cross link proteins providing cell stability

What variables can affect post mortem decomposition?

• tissue

• type of animal

• cause of death

• environmental temperature

• body temperature

• microbial flora

Which tissues autolyse quickly?

• intestinal mucosa

• brain

• spinal cord

Striated muscle has the ability to contract after death which can lead to what?

artifacts like rigor mortis

How long does it take for rigor mortis to occur?

1-6 hours after death

How long does rigor mortis last?

1-2 days after it commences

Cooling of the carcass slows autolysis, but why can we not freeze it?

it destroys tissue architecture and cellular integrity due to ice crystal formation

Abundant adipose tissue in overweight animals or thick wool will retain heat within the body for longer, which causes what?

autolysis to progress more rapidly

Febrile animals autolyse faster, why?

higher body temperatures

Hot external or environmental temperatures will do what to the rate of autolysis?

increase

Microbial flora will produce what?

gas

The gas produced by microbial flora cause what?

bloat of tissues and organs

The bloat resulting from gas production of microbial flora can result in what post mortem?

prolapse of the rectum, uterus, or proptosis of the eyes

Can the diaphragm rupture post mortem?

Yes

If the body has decomposed to the point that organs are liquidy, should you send that to the pathologist?

No, if you think it’s too decomposed they will also think it is too decomposed and they will still charge you even if they cannot use the sample!

What is liver mortis or hypostatic congestion?

the gravitational pooling of blood after death which results in discoloration of tissues

Can postmortem lesions mask antemortem lesions?

Yes

Can you always distinguish postmortem lesions from antemortem lesions?

No, which is why you make a differentials list for both postmortem and antemortem possibilities