Adverse Events of Special Interest (AESI) and related risks: Thrombosis with thromboembolism syndrome (TTS)



Refers to the formation of a blood clot in one of the body's large veins. Most often this formation occurs in the lower limb. The blood clot (thrombus) can block some or all of the blood flow. Thrombosis is a serious condition, due mainly to the high risk of developing a pulmonary thromboembolism, which occurs in a third of patients with thrombosis and has a high mortality rate. 

Risk factors and diseases

Risk factors: Acquired (vitamin K deficiency, liver disease, disseminated intravascular coagulation, and severe liver disease); hereditary (antithrombin deficiency, dysfibrinogenemia, factor V Leiden mutation, protein C deficiency, protein S deficiency, prothrombin mutation 20210A); clinical (advanced age, hospitalization for acute medical illness, long-haul flights [duration >4 hr.], obesity, pregnancy [including the postpartum period]; surgical (central venous access, major surgery, orthopedic surgery, trauma or fracture). 

Diseases: Antiphospholipid syndrome, congestive heart failure, inflammatory bowel disease, malignancy, myeloproliferative disorders, myocardial infarction, polycythemia vera, previous venous thromboembolism (VTE), sepsis, stroke, and varicose veins. 

Medications: Drug-induced: oral contraceptive pills, administration of intravenous immunoglobulin, antipsychotic drugs; antiestrogens, chemotherapy, heparin-induced thrombocytopenia, high-dose progestogen therapy, hormone replacement therapy, oral contraceptives, vaginal ring for birth control, strontium ranelate, thalidomide, and lenalidomide.

Vaccines: In acute viscerotropic disease associated with yellow fever vaccine, disseminated intravascular coagulation (increased prothrombin time or activated partial thromboplastin time with increased fibrinogen degradation products) and bleeding have been observed.


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