What is Primary Hemostasis?

Primary Hemostasis
The clot in the esophagus at the site of the primary hemostasis. Combined use of clips and nylon snare ("tulip-bundle") as a rescue endoscopic bleeding control in a mallory-weiss syndrome. Ivekovic H, Radulovic B, Jankovic S, Markos P, Rustemovic N - Case reports in gastrointestinal medicine (2014). Not Altered. CC.

Primary hemostasis is the formation of the initial platelet plug.

There are four steps are four steps of primary hemostasis, and are as follows:

Step 1: Transient vasoconstriction of the damaged vessel wall that is mediated by stimulation and endothelin release from endothelial cells

Step 2: Platelet adhesion to the surface of damaged vessel. Von Willebrand factor (vWF) binds exposed subendothelial collagen. Platelets bind vWF using the GPIb receptor.

Step 3: Platelet degranulation. Adhesion causes shape change in platelets and degranulation with release of multiple mediators. ADP is released from platelet dense granules which promotes exposure of GPIIb/ IIIa receptor on platelets. TXA2 is synthesized by platelet cyclooxygenase (COX) and released; promotes platelet aggregation

Step 4: Platelet aggregation. Platelets aggregate at the site of injury via GPIIb/IIIa using fibrinogen as a linking molecule which results in formation of a weak platelet plug.

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Last updated on May 24, 2022