Haemostasis and Haemorrhagic Disorders 2024

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Questions and Answers

Which clinical presentation is most indicative of acute DIC?

Bleeding diathesis (correct)

Cyanosis and respiratory failure

Oliguria and acute renal failure

Thrombotic events

What laboratory study is essential for diagnosing DIC?

Platelet count

Complete blood count

D-dimer levels (correct)

Liver function tests

What is the main focus of treatment in cases of DIC?

To provide constant monitoring without intervention

To administer high doses of anticoagulants

To treat or remove the underlying cause (correct)

To increase platelet levels through transfusion

What is a potential outcome of poor management in DIC treatment?

Uncontrolled bleeding Signup and view all the answers

Chronic DIC is most commonly associated with which condition?

Cancer Signup and view all the answers

Which glycoprotein is responsible for binding collagen during platelet adhesion?

Gp1a/IIa Signup and view all the answers

What role do glycoprotein IIb/IIIa play in platelet aggregation?

They form a reversible plug. Signup and view all the answers

Which pathway of the coagulation cascade is assessed by prothrombin time (PT) assay?

Extrinsic pathway Signup and view all the answers

Which factors are involved in the coagulation cascade as cofactors?

II, VII, IX, and I Signup and view all the answers

What initiates the secretion of granule contents in platelets?

Thrombin and ADP Signup and view all the answers

Which factor is considered a key component in both intrinsic and extrinsic pathways of the coagulation cascade?

Factor VII Signup and view all the answers

In which component of secondary hemostasis do enzymes, substrates, and cofactors play a role?

Coagulation cascade Signup and view all the answers

Which substance is characterized as a potent aggregator of platelets?

Thromboxane A2 Signup and view all the answers

Which type of cancer is most frequently associated with disseminated intravascular coagulation (DIC)?

Acute promyelocytic leukaemia Signup and view all the answers

What is a major consequence of widespread fibrin deposition in DIC?

Microangiopathic haemolytic anaemia Signup and view all the answers

What triggers DIC in the context of massive trauma?

Release of procoagulants like tissue factor Signup and view all the answers

Which organ is characterized by microinfarcts and haemorrhage in DIC?

Brain Signup and view all the answers

Plasmin contributes to which of the following conditions in DIC?

Haemorrhagic diathesis Signup and view all the answers

What morphological change occurs in the lungs due to DIC?

Fibrin thrombi in alveolar capillaries Signup and view all the answers

In which context can DIC onset be described as fulminant?

Amniotic fluid embolism Signup and view all the answers

Which of the following statements about organ changes in DIC is accurate?

Heart shows thrombi in small vessels Signup and view all the answers

What is the primary function of haemostasis?

To maintain blood in a fluid, clot-free state Signup and view all the answers

Which factor activates the coagulation cascade in secondary haemostasis?

Tissue factor (TF) Signup and view all the answers

What is the role of thrombin in secondary haemostasis?

To cleave fibrinogen into insoluble fibrin Signup and view all the answers

What is the immediate response to vascular injury in haemostasis?

Vasoconstriction Signup and view all the answers

How do normal endothelial cells contribute to haemostasis?

By maintaining antithrombotic activity Signup and view all the answers

Which of the following is a characteristic of primary haemostasis?

Formation of a platelet plug Signup and view all the answers

What leads to the eventual resorption of a clot?

Counter-regulatory mechanisms like t-PA Signup and view all the answers

What is released from activated endothelial cells that promote thrombosis?

Prothrombotic factors Signup and view all the answers

What is a common presentation of Disseminated Intravascular Coagulation (DIC)?

Excessive formation of thrombi and signs of bleeding Signup and view all the answers

Which of the following conditions may lead to the activation of DIC?

Trauma or burns to tissues Signup and view all the answers

Which factor does TNF promote that contributes to DIC?

Endothelial cell necrosis Signup and view all the answers

How does DIC affect hemostasis?

By depleting factors necessary for proper blood clotting Signup and view all the answers

What type of hemorrhages can be associated with generalized defects in small vessels?

Purpura and ecchymosis Signup and view all the answers

What role do procoagulants from adenocarcinomas play in relation to DIC?

They directly activate platelets in the microvasculature. Signup and view all the answers

What can the presence of microthrombi in DIC lead to?

Infarction and tissue hypoxia Signup and view all the answers

Which statement is true regarding the size of ecchymosis?

Ecchymosis is always larger than 2 cm. Signup and view all the answers

Study Notes

Haemostasis

Maintains blood in a fluid, clot-free state, crucial for vascular integrity.
Involves blood clot formation at injury sites; balances clotting and bleeding.
Imbalance leads to haemorrhagic disorders (excessive bleeding) or thrombotic disorders (excessive clotting).

Steps in Haemostasis

Vasoconstriction: Immediate response to injury; mediated by neurogenic mechanisms and endothelin; transient effect.
Primary Haemostasis: Formation of a platelet plug after vascular injury:
- Exposure of von-Willebrand factor and collagen activates platelets.
- Activated platelets transform and recruit more platelets, forming a plug.
Secondary Haemostasis: Involves fibrin deposition:
- Tissue factor (TF) released from subendothelial cells activates coagulation cascade.
- Thrombin activation converts fibrinogen to insoluble fibrin, stabilizing the platelet plug.

Clot Stabilization and Resorption

Platelet plug and fibrin contract to form a permanent clot.
Tissue plasminogen activator (t-PA) initiates fibrinolysis, limiting clot formation and promoting tissue repair.

Role of Endothelial Cells

Central to maintaining haemostasis balance between thrombosis and antithrombosis.
Normal endothelial cells produce anticoagulants; become prothrombotic after injury.
Factors triggering endothelial activation include trauma, infections, inflammation, and toxins.

Platelet Function

Derived from megakaryocytes; shape changes upon activation.
Activation sequence:
- Adhesion facilitated by Gp1a/IIa binding to collagen.
- Shape change allows GpIIb/IIIa to bind fibrinogen; phospholipids bind calcium.
- Secretion of granule contents (thrombin and ADP) enhances aggregation via thromboxane A2.

Coagulation Cascade

Central to secondary haemostasis; drives formation of thrombin.
Series of enzymatic reactions involving activated coagulation factors, proenzymes, and cofactors, some requiring calcium ions and Vitamin K.
Divided into extrinsic and intrinsic pathways, defined by laboratory tests.

Clinical Applications of Coagulation Cascade

Prothrombin time (PT) assay evaluates extrinsic pathway function; identifies defects causing purpura and ecchymosis.

Disseminated Intravascular Coagulation (DIC)

Acute or chronic thrombohemorrhagic disorder with excessive coagulation leading to microvascular thrombi.
Secondary complication of conditions like sepsis, trauma, and certain cancers, causing tissue hypoxia and hemorrhage.

Mechanisms Triggering DIC

Release of procoagulants (placenta in obstetric complications, tissue injury, certain adenocarcinomas).
Endothelial injury forces expression of tissue factor, pushing hemostatic balance to favor coagulation.

Consequences of DIC

Widespread fibrin deposition leads to organ ischemia and microangiopathic hemolytic anemia.
Consumption of platelets and clotting factors leads to a bleeding tendency.
Fibrin degradation products inhibit platelet aggregation and coagulation.

Diagnosis and Clinical Features of DIC

Diagnosis involves clinical assessment and laboratory tests measuring fibrinogen, platelets, PT, PTT, and D-dimers.
Symptoms range from anemia and respiratory failure to acute renal failure and circulatory shock.

Prognosis and Treatment of DIC

Prognosis varies; depends on the underlying cause.
Definitive treatment focuses on addressing the inciting disorder.
Management balances concerns of thrombosis and bleeding; controversial use of anticoagulants/procoagulants in specific cases.

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Description

Explore the crucial mechanisms of haemostasis, the process that keeps blood in a fluid state and prevents excessive bleeding. This quiz covers the balance between clotting and bleeding, as well as the steps in haemostasis and associated disorders. Understand the importance of thrombosis and haemorrhage in clinical settings.