Vena cava filter

In medicine, vena cava filters, also called Greenfield filters, are "mechanical devices inserted in the inferior vena cava that prevent the migration of blood clots from deep venous thrombosis of the leg."

Inferior vena cava filter reduces pulmonary embolism and is an option for patients with an absolute contraindication to anticoagulant treatment (e.g., cerebral hemorrhage) or those rare patients who have objectively documented recurrent pulmonary embolisms while on anticoagulation.

Adverse effects
Vena cava filters are themselves potential foci of thrombosis, IVC filters are viewed as a temporizing measure for preventing life-threatening pulmonary embolism.