A significant provoking factor is the surgical intervention itself and the resulting state of hypercoagulation (increased blood clotting), although phlebectomy (removal of varicose veins) does not belong to operations with a high risk of VTEC. The second significant factor is bed rest, immobility.
Also, the likelihood of venous thromboembolism increases in patients:- over 40 years old;
- taking hormonal drugs (estrogens) or other drugs that affect blood clotting;
- with obesity, varicose veins of the extremities, cancer, infection;
- with deep vein thrombosis or pulmonary embolism in the past.