A 3-year-old boy with pronounced hemorrhagic syndrome has no antihemophilic globulin A (factor VIII) in the blood plasma. Hemostasis has been impaired at the following stage:

Answer options

1. Conversion of prothrombin to thrombin
2. Internal mechanism of prothrombinase activation
3. Conversion of fibrinogen to fibrin
4. Blood clot retraction
5. External mechanism of prothrombinase activation

Explanation

Hemophilia is a rare disorder in which your blood doesn't clot normally because it lacks sufficient blood-clotting proteins (clotting factors) factor VIII, also called antihemophilic factor intrinsic clotting.