Bleeding 48 hours after tooth extraction is most likely due to deficiency of which factor?

Bleeding 48 hours after tooth extraction is most likely due to deficiency of which factor?

• A. plasminogen
• B. alpha-2 antiplasmin
• C. factor XII
• D. factor XIII

Answer: (D)

The pattern here is about clot stabilization rather than initial clot formation. Factor XIII functions to crosslink fibrin strands and to attach antifibrinolytic proteins like alpha-2 antiplasmin into the clot, making it strong and resistant to breakdown. If this factor is deficient, a clot can form but it’s unstable and slowly dissolves over the next day or two, leading to bleeding that appears about 2 days after a dental extraction. This delayed bleeding after a minor mucosal injury is classic for Factor XIII deficiency, even when routine tests like PT or aPTT are normal because those measures assess clot formation, not stabilization. The other options relate to either the formation of the clot or to fibrinolysis in ways that don’t produce the same delayed post-procedural bleeding pattern as FXIII deficiency.

The pattern here is about clot stabilization rather than initial clot formation. Factor XIII functions to crosslink fibrin strands and to attach antifibrinolytic proteins like alpha-2 antiplasmin into the clot, making it strong and resistant to breakdown. If this factor is deficient, a clot can form but it’s unstable and slowly dissolves over the next day or two, leading to bleeding that appears about 2 days after a dental extraction. This delayed bleeding after a minor mucosal injury is classic for Factor XIII deficiency, even when routine tests like PT or aPTT are normal because those measures assess clot formation, not stabilization. The other options relate to either the formation of the clot or to fibrinolysis in ways that don’t produce the same delayed post-procedural bleeding pattern as FXIII deficiency.