Bleeding & clotting disorders

BLEEDING AND CLOTTING DISORDERSLec.2

Bleeding disorders may be classified as
vascular integrity .
platelet numbers and platelet function .
abnormalities of coagulation .

Classification of hemostatic abnormalities

Vessel wall disorders can result in hemorrhagic features.
Bleeding is usually mild and confined to the skin,mucosa, and gingiva.
Vascular purpura can result from damage to capillary endothelium, due to abnormalities in the vascular subendothelial matrix or extravascular connective tissue bed, or from abnormal vessel formation.

Vascular disorders

Scurvy
resulting from dietary deficiency of water-soluble vitamin C which lead to defects in collagen synthesis.
Vitamin C is necessary for the synthesis of hydroxyproline, an essential constituent of collagen.


clinical signs
petechial hemorrhages at the hair follicles
and purpura on the back of the lower extremities
Hemorrhage can occur in the muscles, joints, nail beds, and gingival tissues.
Gingival involvement may include swelling, friability, bleeding, secondary infection, and loosening of teeth.

Cushing’s syndrome

resulting from excessive exogenous or endogenous corticosteroid intake or production, leads to general protein wasting and atrophy of supporting connective tissue around blood vessels. Patients may show skin bleeding or easy bruising.

Persistently bleeding lesions may be treated with cryotherapy laser ablation electrocoagulation or resection.

Platelet disorders may be divided into two categories by etiology

— congential and acquired—
and into two additional categories by type—thrombocytopenias and thrombocytopathies

Platelet disorders

Thrombocytopenia
occur when platelet quantity is reduced and are caused by one of three mechanisms: decreased production in the bone marrow, increased sequestration in the spleen, or accelerated destruction.

Thrombocytopenia may be a component of other hematologic disease such as, aplastic anemia and leukemia.
Bone marrow suppression from cytotoxic chemotherapy can result in severe thrombocytopenia.


Thrombocytopathies
is qualitative platelet disorders, may result from defects in any of the three critical platelet reactions: adhesion, aggregation, or granule release.

Medications can also reduce absolute numbers of platelets or interfere with their function, resulting in postsurgical hemorrhage.
Aspirin induces a functional defect in platelets detectable as prolongation of BT.

Coagulation disorders may be either congenital or acquired secondary to drugs or disease processes.

Coagulation disorders

Congenital coagulopathies
Inherited disorders result from deficiency of a number of factors that are essential in the coagulation cascade
Clinical bleeding can vary from mild to severe, depending on the specific clotting factor affected and the level of factor deficiency.

Hemophilia A

A deficiency of F VIII( the antihemophilic factor)
is inherited as an X-linked recessive trait that affects males, The trait is carried in the female without clinical evidence of the disease, although a few do manifest mild bleeding symptoms.

Hemophilia B.

FIX (Christmas factor) deficiency is found in hemophilia B. The genetic background, factor levels, and clinical symptoms are similar to those in hemophilia A.



Von Willebrand’s Disease

This disorder is usually transmitted as an autosomal dominant trait.

defects in von willebrand factor protein and resulting in impaired platelet aggregation.


The clinical features of the disease are usually mild and include mucosal bleeding such as epistaxis, soft tissue
hemorrhage, and prolonged bleeding after surgery or trauma.

Heparin.

heparin therapy used as prophylaxis or treatment for venous thromboembolism
. Heparin is a potent anticoagulant that inhibit activation of Fs IX, X, and XI, thereby reducing thrombin generation and fibrin formation.
Anticoagulant-related coagulopathies

warfarin

used for anticoagulation to prevent recurrent thrombotic phenomena (pulmonary embolism, venous thrombosis, stroke, myocardial infarction), to treat atrial fibrillation, and in conjunction with prosthetic heart valves.

Liver Disease. Patients with liver disease may have a wide spectrum of hemostatic defects depending upon the extent of liver damage.
due to:
abnormal vitamin K–dependent factor.
Thrombocytopenia and thrombocytopathy are also common in severe liver disease


Disease-related coagulopathies

Vitamin K Deficiency

Vitamin K is a fat-soluble vitamin that is absorbed in the small intestine and stored in the liver. It plays an important role in hemostasis. Vitamin K deficiency is associated with the production of poorly functioning vitamin K dependent Fs II, VII, IX, and X.
Deficiency is rare but can result from inadequate dietary intake, intestinal malabsorption, or loss of storage sites due to hepatocellular disease.

Disseminated intravascular coagulation (DIC)

is a pathological process characterized by the widespread activation of the clotting cascade that results in the formation of blood clots in the small blood vessels throughout the body. This leads to compromised tissue blood flow and can ultimately lead to multiple organ damage. In addition, as the coagulation process consumes clotting factors and platelets,
DIC does not occur by itself but only as a complicating factor from another underlying condition, usually in those with a critical illness (infection, malignancy)

Disorders of the fibrinolytic system can lead to hemorrhage when clot breakdown is enhanced, or excessive clotting and thrombosis when clot breakdown mechanisms are retarded
Fibrinolytic disorders