Thrombotic Disorders

Answer: A

Explanation: When endothelial cell–associated thrombomodulin is activated, it can in turn activate protein C, which, in association with protein S, inactivates FVIIIa and FVa and inhibits thrombin production. Vasoconstriction and release of VWF are steps involved in primary hemostasis. Secondary hemostasis is initiated by the release of tissue factor upon vessel injury.
Question 8

Answer: B

Explanation: The indications for systemic thrombolysis are life-, organ-, or limb-threatening thrombosis such as arterial thrombosis outside of the central nervous system, intracardiac thrombus, pulmonary embolus (especially when the patient is hemodynamically unstable), and extensive deep venous thrombosis (superior vena cava syndrome, occlusive IVC thrombosis, bilateral renal vein thrombosis with renal compromise). Contraindications include active major bleeding in intracranial, retroperitoneal, or gastrointestinal sites; significant potential for uncontrolled local bleeding; major surgery within the past 10 days; neurosurgery (including spinal surgery) within the preceding 3 weeks; and new or recurrent stroke. The coagulation profile should be checked prior to initiation and platelets, fibrinogen, and hemoglobin should be corrected. Neonates are known to have lower baseline levels of plasminogen than older children and plasminogen should be empirically replaced with fresh frozen plasma prior to initiation of lysis. Because tissue plasminogen activator (tPA) will break down clots but not prevent new clot formation, prophylactic doses of UFH should be administered during lysis.
Question 9