Hemostasia, Epistaxe e Hemorragia: Definições, Fases e Ligações Clínicas

Understanding the terminology of bleeding is fundamental to clinical practice. Hemostasis is the physiologic process that arrests bleeding; epistaxis is a nosebleed; and hemorrhage denotes excessive, uncontrolled bleeding.

Phases of Hemostasis

1. Primary Hemostasis (Platelet Plug Formation): Vascular spasm (vasoconstriction) followed by platelet adhesion, activation, and aggregation at the injury site, forming a soft plug.
2. Secondary Hemostasis (Coagulation Cascade): A series of enzymatic reactions (intrinsic, extrinsic, and common pathways) culminating in thrombin generation, conversion of fibrinogen to fibrin, and stabilization of the platelet plug into a firm clot.
3. Fibrinolysis: Plasmin-mediated degradation of the fibrin clot after tissue healing is underway, preventing thrombosis.

Clinical Connections

• Epistaxis represents a failure of local hemostasis, most commonly at Kiesselbach's plexus (anterior nasal septum).
• Hemorrhage reflects systemic hemostatic failure due to trauma, coagulopathy, anticoagulant therapy, or vascular rupture.
• Laboratory assessment: Platelet count/function, PT/INR, aPTT, fibrinogen, D-dimer, and viscoelastic testing (TEG/ROTEM) evaluate different hemostasis components.

Accurate distinction guides targeted intervention: local cautery/packing for epistaxis vs. factor replacement, transfusion, and surgical control for hemorrhage.