Hemostasis includes three steps that occur in a rapid sequence: (1) vascular spasm, or vasoconstriction, a brief and intense contraction of blood vessels; (2) formation of a platelet plug; and (3) blood clotting or coagulation, which reinforces the platelet plug with fibrin mesh that acts as a glue to hold the clot …

Hemophilia is a bleeding disorder typically caused by mutations in the genes that provide instructions for making certain proteins — blood clotting factors VIII, IX, or XI — which are needed for proper blood clotting.

The mechanism of hemostasis can divide into four stages. 1) Constriction of the blood vessel. 2) Formation of a temporary “platelet plug.” 3) Activation of the coagulation cascade. 4) Formation of “fibrin plug” or the final clot.

Secondary hemostasis refers to the cascade of enzymatic reactions that ultimately results in the conversion of fibrinogen to fibrin monomers. Fibrin monomers are then cross-linked into insoluble strands that serve to stabilize the loose platelet clot formed in primary hemostasis.

The most common inherited diseases are von Willebrand disease (primary hemostasis), which is the most common inherited disorder of hemostasis, and hemophilia A (factor VIII deficiency, secondary hemostasis).

The goal of secondary hemostasis is to stabilize the platelet aggregate by weaving a meshwork of fibrin to cement the thrombus. The end result is the formation of thrombin, which cleaves fibrinogen to fibrin and thus the clot can be stabilized.

The pathway of blood coagulation activated by tissue factor, a protein extrinsic to blood, is known as the extrinsic pathway (Figure 1). Tissue factor serves as a cofactor with factor VII to facilitate the activation of factor X. Alternatively, factor VII can activate factor IX, which, in turn, can activate factor X.

So let’s get into the details of secondary hemostasis. The process of forming the fibrin mesh begins via two pathways –the extrinsic and intrinsic pathways. The intrinsic pathway is called intrinsic because all of the factors required to activate it are intrinsic, or found within the blood.

Primary hemostasis refers to platelet aggregation and platelet plug formation. Secondary hemostasis refers to the deposition of insoluble fibrin, which is generated by the proteolytic coagulation cascade. This insoluble fibrin forms a mesh that is incorporated into and around the platelet plug.

Hemostasis or haemostasis is a process to prevent and stop bleeding, meaning to keep blood within a damaged blood vessel (the opposite of hemostasis is hemorrhage). It is the first stage of wound healing. This involves coagulation, blood changing from a liquid to a gel.

Platelets are not only involved in platelet plug formation but are also crucial for formation of fibrin (secondary hemostasis). Assembly of these complexes on this surface markedly amplifies fibrin formation (called the propagation phase of secondary hemostasis).

Primary hemostasis serves to immediately limit bleeding through the formation of a loose platelet plug. Platelets play a key role in the rapid response to blood vessel injury by: Adhering to the endothelial wall at the site of injury. Releasing potent anticoagulant compounds.

Primary hemostasis occurs when platelets attach to a damaged or disrupted area of the endothelium. Normal hemostasis occurs in three main stages. Primary hemostasis occurs when platelets attach to a damaged or disrupted area of the endothelium.

The end result of primary haemostasis is the formation of a stable platelet plug around which a fibrin network can then be built. This same process is responsible for the pathogenic thrombus formation in patients with arterial disease.

In summary, to form a firm platelet plug, it is necessary to have healthy blood vessels, VWF, and sufficient and well-functional platelets. Diseases of these three players cause primary hemostatic disorders including vascular anomalies, von Willebrand disease (VWD), thrombocytopenia, and platelet function disorders.

Numerous hemostatic abnormalities have been associated with acute and chronic renal disease. The most common abnormalities are defective platelet aggregation, decreased platelet adhesiveness, decreased platelet factor-3 availability, and prolongation of the bleeding time.

The bleeding time (BT) and platelet function analyzer (PFA) are used as screening tests of primary hemostasis. The bleeding time is an in vivo screening test of primary hemostasis which measure the time to cessation of bleeding of a uniform skin cut.

What are the symptoms of a bleeding disorder?

• unexplained and easy bruising.
• heavy menstrual bleeding.
• frequent nosebleeds.
• excessive bleeding from small cuts or an injury.
• bleeding into joints.