Exam 2 (Lecture 10) - Hemorrhage and Thrombosis

Question 1

Arrest of Hemorrhage

Answer 1

1) Formation of a clot (hemostasis)

2) Pressure of surrounding tissue (internal hemorrhage)

3) If massive trauma/blood loss: decreased BP
- decreased BP > blood flow slows > stasis > death

Question 2

Describe the methods of disposal for escaped blood.

Answer 2

1) Small hemorrhages (serum absorbed)
- this is when we start seeing the cholesterol crystals/bruising
patterns

2) Large hemorrhages
clot > contraction > fluid to lymphatics
- macrophages
- fibroblasts (make collagen)

3) Large hematoma
- All of the above PLUS seromas (RBCs and serum)
- bacteria love seromas!

Question 3

What is thrombosis?

Answer 3

Excessive or inappropriate intravascular blood coagulation in the living animal.

Question 4

What are the three main factors of pathogenesis that leads to thrombosis?

Answer 4

1) Endothelial injury

2) Blood turbulence or stasis

3) Hypercoagulability

**AKA Virchow’s Triad

Question 5

What is the significance of thrombosis?

Answer 5

1) Ischemia (blocking blood flow to that location):
- depends on location and collateral circulation

2) Embolism:
- free mass (or air) in circulation

3) Infarction:
- the outcome is ischemic necrosis (coagulative necrosis)

Question 6

What are the fates of thrombi?

Answer 6

1) Propagation
- Ex: toward the heart

2) Embolism
- Ex: pulmonary embolism

3) Fibrinolysis
- Via plasmin
- Results in resolution (clot dissolution)

4) Organization or recanalization
- Ex: organized and incorporated into blood vessel wall
- Ex: recanalized so that blood can flow through other areas

Question 7

Describe an arterial thrombus.

Answer 7

1) Initiated at areas of endothelial damage.

2) Downstream growth (away from site of attachment)

3) “Tail” not attached; can break off
- thromboemboli

4) Prevents oxygenated blood from entering site

Question 8

Describe venus thrombi.

Answer 8

1) Areas of stasis

2) Often occlusive

3) Upstream growth (toward attachment)

4) Prevents deoxygenated blood from leaving site

Question 9

Describe a venous infarct. What are some examples of venous infarct?

Answer 9

Occurs when there is pressure on a vessel.

Veins are more at risk of compression due to less muscle in the vessel.

Examples:
- a strangulating lipoma that has cut off blood supply to the SI
- twisted colon resulting in stasis of deoxygenated blood
- inguinal hernia with intestinal entrapment

Question 10

Compare the gross appearance of a venous infarct and an arterial infarct.

Answer 10

Venous infarct:
- will appear dark red/purple

Arterial infarct:
- will appear pale due to lack of blood flow
- zones of hyperemia around the pale areas (will undergo
coagulative necrosis)

Question 11

Are “chicken fat” clots normal post mortem?

Answer 11

Yes, they are seen in animals that are in high stress situations.

Question 12

What are some types of emboli?

Answer 12

1) Blood (thromboemboli)
2) Bacteria
3) Fat
4) Air (from IV injections/catheterization)
5) Parasites
6) Cartilage

Question 13

What is hemorrhage? What causes it?

Answer 13

The escape of blood from the blood vascular system.

Hemorrhage by rupture:
- Causes:
- Trauma
- Vessel wall necrosis (burns, insects, etc)
- Vessel wall invasion by a neoplasm
- Primary vascular disease
- Atherosclerosis:
*Brain: stroke
* Coronary arteries: occlusion > MI

Question 14

What does the clinical significance of a hemorrhage depend on?

Answer 14

Amount
Rate
Site (how easy will it be to stop the hemorrhage?)
Duration
Hypovolemic shock
Fluid redistribution
Anatomic consequences
Acute
Chronic

Question 15

What are the 2 main types of hemorrhage?

Answer 15

1) Regional
- diffuse
- hematoma

2) Surface
- petechiae
- ecchymosis
- purpura
- paint brush/suffusive

Question 16

What is hemorrhage by diapedesis and how does it occur?

Answer 16

Passage of RBCs through an intact vascular wall.

Site: lung and GI tract

Situation: left heart failure

Problem: increased intravascular pressure in pulmonary capillaries

Question 17

What are the major mechanisms of hemorrhage?

Answer 17

1) Endothelial/vessel injury

2) Platelet dysfunction or thrombocytopenia

3) Coagulation disorders
- Acquired:
- hepatic dysfunction
- vitamin K antagonism (II, VII, IX, X)
- disseminated intravascular coagulation
- Inherited:
- hemophilia

Question 18

Describe the pathogenesis of DIC.

Answer 18

1) Primary disease (like septicemia or neoplasia)
- toxins, vascular damage, viral infections, etc

2) Endothelial damage (widespread)

3) Microthrombi formation
- ischemic injury (leads to multiple organ failure)
- tissues not getting blood
- consumption of platelets and coagulation factors (spontaneous)
- activation of fibrinolysis (fibrin degradation products)
** Last 2 bullet points lead to hemorrhagic diathesis

Question 19

How do you diagnose consumption coagulopathy?

Answer 19

Thrombocytopenia (less than 50,000) - at risk for hemorrhage

Increased fibrin degradation products (FDPs): D-dimers

Increased clotting time
- PT (extrinsic)
- PTT (intrinsic)
* ways to measure arms of clotting cascade

Question 20

What are the two major consequences of DIC?

Answer 20

1) Hemorrhage
- consumptive coagulopathy (continual hemorrhage)

2) Multiple organ failure due to ischemia
- microthrombi in microvasculature
- hypovolemic shock possible (blood volume leaving vascular
space)