Pathology of Venous Circulation

Question 1

Learning outcomes

Answer 1

• Describe the clinicopathological features of varicose veins and stasis dermatitis
• Describe the main causes and consequences of venous thromboembolism
• Compare thrombosis and embolism
• Explain other categories of venous embolism such as gas embolism, fat embolism and amniotic fluid embolism

Question 2

Veins- definition

Answer 2

Veins – blood vessels which in most cases* carry oxygen-depleted blood towards the heart.*
The exceptions are the pulmonary veins and umbilical vein which carry oxygen rich blood.
In the leg – there are superficial veins just beneath the skin and also deep veins present within leg muscles
Lower limb anatomy in detail next year

Question 3

1. Varicose veins

Answer 3

Superficial veins
Varicose veins are swollen and enlarged distended rope-like superficial veins of the leg.
Very common, mostly due to gravity. Can be painful or unsightly.

Question 4

2. Stasis dermatitis (statis eczema/ gravitational eczema)

Answer 4

Poor blood flow in superficial or deep leg veins causes blood to accumulate chronically.
Red blood cells break down to haemosiderin pigment. Pigmentation and inflammation of skin which can ulcerate

Question 5

3. Deep vein thrombosis

Answer 5

Thrombosis is a normal physiological process when a blood vessel is injured for example a blood clot forms to prevent bleeding.
The blood clot or thrombus is composed of platelets, red blood cells and a protein meshwork (of fibrin)

Whilst thrombus formation is a normal response to an injury, there are several medical disorders caused by harmful thrombosis. Deep vein thrombosis = Formation of thrombus in deep veins of the legs (for example in calf or thigh)

Soluble circulating precursor proteins (clotting factors) are converted to insoluble circulating proteins via the coagulation cascade
*Thrombosis can also occur in the arterial system eg. coronary artery atheroma with thrombosis and carotid artery thrombosis however in this presentation we are discussing venous thrombosis

Question 6

Virchow’s triad

Answer 6

Thrombosis in general can be caused by damage to
1. blood vessel walls,
2. abnormal blood flow eg. stagnant flow or
3. abnormal blood constituents.
These three elements are described in pathology textbooks as Virchow’s triad.
Attributed to the German pathologist Dr Rudolf Virchow (1821– 1902).

Question 7

4. Pulmonary thromboembolism (venous thromboembolism)

Answer 7

Pulmonary embolism is a blockage in one of the pulmonary arteries in your lungs. In most cases, pulmonary embolism is caused by blood clots that travel to the lungs from deep veins in the legs or, rarely, from veins in other parts of the body (deep vein thrombosis)
no. 1 cause of preventable death in hospitals

Saddle pulmonary embolism will most likely originate from deep leg vein

Question 8

5. Gas embolism/ air embolism

Answer 8

Instead of a thrombus in the venous system, air or oxygen will be present
Fat embolism- adipose tissue into venous system, which can occur from brazilian butt lift surgery, or bone fractures