Venous thromboembolism (VTE) can affect men and women of all ages, races and ethnicities. People at the highest risk include those with cancer, having surgery or anyone with major trauma such as fractures or immobilization. They should ask about getting prevention treatments. Hospitalization for any reason increases the risk, so people in the hospital should ask about VTE prevention.
VTE risk factors
- Major surgery or hospitalizations — Blood clots are likely to form around the surgery site and immobility causes the blood to slow and potentially clot.
- Heart conditions, such as heart attack or congestive heart failure
- Chronic conditions including high blood pressure, diabetes and kidney disease
- Lower-extremity paralysis due to spinal cord injury
- Fracture of the pelvis, hip or long bones
- Infections, such as the virus that causes COVID-19
- Multiple trauma
- Cancer — People with cancer are more likely to be hospitalized and have surgery which leads to immobility. Cancers of the pancreas, lung, ovary, stomach, lymphoma and adenocarcinoma (cancers that start in glandular tissues) of unknown origin are associated with the highest incidence of a life-threatening blood clot.
Individually, the factors below are not enough to justify preventive measures for VTE. But a combination of two or more may be cause for action – and could influence the type and duration of the prevention treatment.
- Prior VTE — People with a previous episode of VTE have a high chance of recurrence.
- Age — People over 40 are at higher risk, and that risk doubles with each decade.
- Obesity — People with obesity have increased risk of VTE, and the higher the weight, the higher the risk.
- Immobility — Prolonged immobility, such as during long travel, combined with other major risk factors increases the likelihood of VTE. The blood is slowed during immobility for long periods and high altitude can activate the clotting system.
- Oral contraceptives or estrogen treatment for menopause symptoms may cause the blood to clot more easily than normal. which causes the blood cells to bind more readily.
- Family history of VTE— especially if this is in a first-degree relative (parent, sibling, child)
- Physical inactivity
- Acquired or hereditary coagulation disorders
- Certain nutritional deficiencies (such as folate or vitamin B12 deficiency) can lead to acquired causes of thrombosis.
VTE and pregnancy
Women who are pregnant or have just had a baby are at greater risk of developing a blood clot. The risk is greater in the presence of the following other factors:
- Previous blood clots
- A genetic predisposition to VTE or a family history of VTE (especially in a first-degree relative like a parent or sibling)
- Immobilization, such as bed rest and long-distance travel
- Multiple births
- Older maternal age
- Other medical illness during pregnancy, like cancer, serious infection or toxemia/pre-eclampsia