F5 and deep vein thrombosis: In the current study, known thrombophilia was very low in prevalence and was considered present if the patient had positive both family and personal history of thrombosis, had pre-recorded known hereditary thrombophilia (patients in our study had either factor V Leiden, factor II G20210A mutations, and one patient had known factor XII deficiency), or had a highly thrombogenic acquired condition (heparin-induced thrombocytopenia).