Pathology Flashcards
What are the two types of autopsy?
- Hospital
2. Medico-legal
What percentage of autopsies are hospital autopsies and what percentage are medicolegal autopsies?
Hospital - <10%
Medico-legal - >90%
What is the purpose of hospital autopsies?
To confirm how the patient died for audits/teaching/governance/research
What do you need to perform a hospital autopsy?
- Family consent
- Medical certificate for the cause of death
What is the purpose of medico-legal autopsies?
These include coronial and forensic autopsies to determine cause of death.
Who performs autopsies?
- Histopathologists - hospital and coronial autopsies due to natural death, drowning, suicide, accidents, road traffic deaths, fire accidents, industrial deaths
- Forensic pathologists - coronial autopsies due to homicide, death in custody, neglect
What deaths are referred to the coroner?
Presumed natural - unknown cause and not seen by doctor 14 days leading up to death
Presumed iatrogenic - deaths which could be caused by doctor e.g. from operation, abortion
Presumed unnatural - accidents, industrial, homicide
Legislation surrounding autopsies?
Coroners act 1988
Coroners rules 1984 (and 2005 amendments)
Human tissue act 2004
What are the steps performed in an autopsies?
- History/scene - history of events leading to the death e.g. GP summary, police reports, medical reports
- External examination - identities, gender, jewellery, body habitus, modifications, injuries
- Digital autopsy - full body CT scan, if this doesnt determine death then evisceration occurs
- Evisceration - Y shape incision from neck to pubis. Body cavity is opened and organs are examined in situ
- Internal examination - heart/vessels, lungs/trachea/bronchi, liver/gall bladder/pancreas, spleen/thymus/lymph nodes, genitourinary tract, endocrine organs, CNS
- Reconstruction - organs are placed in a viscera bag and placed inside the body before being sewn up
Examples of cells which regenerate
- Hepatocytes
- Pneumocytes
- All blood cells
- Gut epithelium
- Osteocytes
- Skin epithelium
Examples of cells which don’t regenerate
- Myocardial cells
- Neurons
What is the difference between resolution and repair?
Resolution - Initiating factor is removed. It can only occur if the tissue is undamaged or can regenerate itself
Repair - Initiating factor is still present. It only occurs if tissue is damaged and is unable to regenerate itself.
Situations where regeneration occurs?
- Liver tumour resection
- Lobar pneumonia
- Skin wounds
What is the difference between skin abrasion and laceration?
In abrasion only the top layer of skin is removed whereas lacerations are deeper wounds where skin is breached.
How do abrasions heal?
Scab forms, epithelia proliferates/regenerates under the scab for protection
How do lacerations heal?
Healed by first or second intentions.
First intention - two surfaces of incision remain in contact, the wound fills with fibrin and collagen synthesis occurs filling the wound. Epidermal regrowth occurs.
Second intention - two surfaces from incision are not in contact forming a “hole”. Cells grow across the hole and loops of capillaries form. This leads to formation of granulation tissue.
Definition of laminar flow
Fluid flow in parallel direction with little disruption between layers
What are the three predispositions to a thrombus?
- Change in vessel wall - e.g. endothelial cell injury
- Change in blood flow - e.g. change from laminar to turbulent flow
- Changes in blood constituents - eg. thrombocythemia
Two means of preventing thrombosis:
- Aspirin/heparin
2. Leg stockings
What coagulation factors are fibrinogen, fibrin, prothrombin, thrombin?
Fibrinogen - I
Fibrin - Ia
Prothrombin - II
Thrombin - IIa
Definition of thrombosis
A solid mass of blood constituents formed within an intact vascular system during life.
What is a thrombus
Aggregation of platelets and red blood cells.
Definition of an embolus
A mass of material in the vascular system which is able to become lodged in thin vessels and block them
Definition of ischaemia
Reduction in blood flow
Definition of infarction
Reduction in blood flow resulting in cell death
Definition of end artery
An artery which is the only supply of oxygenated blood to tissue
3 examples of areas with a duel blood:
- Lungs
- Liver
- Parts of the brain
Why does a duel blood supply reduce risk of infarction?
If one artery becomes blocked, the tissue still has blood supply from the other artery.
What is a watershed area?
An area of tissue at the boundary of adjacent territories supplied by two different arteries. These areas do not receive much blood supply from either territory and are subject to infarction.
Why do watershed areas become infarcted?
In prolonged periods of low blood pressure or blood loss the area does not receive enough blood and therefore becomes infarcted.
An example of a disease caused by infarction of a watershed area?
Subendocardial myocardial infarction
What is reperfusion injury?
When an ischaemic area of tissue becomes rapidly perfused with oxygen leading to production of radical oxygen species.
In cardiopulmonary resuscitation, how do you try and avoid reperfusion injury?
Patients are cooled down to reduce metabolic rate.
What is atherosclerosis?
A disease in which plaque builds up in arteries.
Which vessels do atherosclerotic plaques occur?
High pressure vessels e.g. systemic vessels not pulmonary.
What is a fatty streak?
A precursor to an atherosclerotic plaque
What are the contents of a plaque?
- Fibrous tissue
- Lipids
- Lymphocytes
Risk factors of atherosclerosis:
- Cigarette smoking
- High blood pressure
- Poorly controlled diabetes
- Hyperlipidemia