This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vascular surgery, Subject name: Surgery
Which of these is not a risk factor for thromboembolism - 
Select and explain. 
A. Myocardial infarction, B. Estrogen therapy, C. Hypeension, D. Superficial thrombophlebitis
C: Hypeension
Answer: C: Hypeension 
Explanation: All those factors which promote DVT are also risk factors for thromboembolism. Superficial thrombophlebitis itself cannot cause thromboembolism (as thrombus formed in superficial thrombophlebitis strongly adhere to the venous wall) but it is a risk factor for DVT. The thrombosis in superficial thrombophlebitis can extend into the deep venous system causing DVT. Estrogen & Myocardial infarction are risk factors for DVT and thromboembolism Estrogen leads to a hypercoagulable state. Myocardial infarction causes bed rest leading to stasis.