What laboratory test evaluates primary hemostasis?

What laboratory test evaluates primary hemostasis?

• A. Activated clotting times
• B. Activated partial thromboplastin time
• C. Buccal mucosal bleeding time
• D. One-step prothrombin time

Answer: (C)

Primary hemostasis refers to how platelets form a plug at the site of a vessel injury, aided by intact vessel walls. The buccal mucosal bleeding time directly tests this by creating a standardized mucosal injury and measuring how long bleeding lasts; a prolonged bleeding time points to platelet dysfunction, low platelet count, or von Willebrand disease, all of which impair the platelet plug formation. The other tests assess the coagulation cascade that stabilizes the plug with fibrin: activated clotting time looks at overall clotting, often in the context of heparin therapy; activated partial thromboplastin time evaluates the intrinsic and common pathways; and prothrombin time evaluates the extrinsic and common pathways. These measure secondary hemostasis, not the initial platelet-dependent plug, so they’re not measures of primary hemostasis.

Primary hemostasis refers to how platelets form a plug at the site of a vessel injury, aided by intact vessel walls. The buccal mucosal bleeding time directly tests this by creating a standardized mucosal injury and measuring how long bleeding lasts; a prolonged bleeding time points to platelet dysfunction, low platelet count, or von Willebrand disease, all of which impair the platelet plug formation. The other tests assess the coagulation cascade that stabilizes the plug with fibrin: activated clotting time looks at overall clotting, often in the context of heparin therapy; activated partial thromboplastin time evaluates the intrinsic and common pathways; and prothrombin time evaluates the extrinsic and common pathways. These measure secondary hemostasis, not the initial platelet-dependent plug, so they’re not measures of primary hemostasis.