Risk level	Risk (%)			Examples
Deep vein thrombosis	Proximal deep vein thrombosis	Fatal pulmonary embolism
Low	<10	<1	0.01	Minor surgery, trauma, or medical illness Major surgery at age < 40 with no other risk factors
Moderate	10-40	1-10	0.1-1	Major surgery with another risk factor Major trauma, medical illness, or burns Emergency caesarean section in labour Minor surgery with previous deep vein thrombosis, pulmonary embolism, or thrombophilia Lower limb paralysis
High	40-80	10-30	1-10	Major pelvic or abdominal surgery for cancer Major surgery, trauma, or illness with previous pulmonary embolish, deep vein thrombosis, or thrombophilia