Deep vein thrombosis (DVT) occurs when a blood clot forms in a vein deep inside a muscle in your body. It usually happens in the legs, but can also develop in your arms, chest, or other areas of your body. And though DVT is common, it can be dangerous. The blood clot can block your circulation or lodge in a blood vessel in your lungs, brain, heart, or other area. The clot can cause severe organ damage and even death -- within hours.
The main cause of DVT is poor blood flow. When circulation slows, blood can pool and more easily form clots, raising your DVT risk.
Certain surgeries can raise your risk of a blood clot. They include:
Surgery that reduces blood flow to a part of your body.
Major surgery on a hip, knee, leg, calf, abdomen, or chest.
Orthopedic surgery, such as a hip replacement.
These are some of the reasons why surgery can increase your DVT risk:
Tissue debris, protein, and fats may move into veins following surgery.
Vein walls can become damaged, which may also release substances that promote blood clotting.
Prolonged bed rest is common following surgery and can allow blood to pool in areas of the body.
Conditions or Treatments That Raise DVT Risk
Surgery isn't the only cause of DVT. Certain medical conditions or treatments may also increase your DVT risk. For starters, any condition that requires bed rest for more than three days increases your DVT risk. Other risk factors, in order from most common to least, include:
An injury that reduces blood flow to part of your body, such as a broken hip or leg.
Cancer, even during treatment.
A previous history of deep vein thrombosis or pulmonary embolism.
An inherited condition that increases blood clotting.
Paralysis from a spinal cord injury.
Current use of hormone therapy, including that used for postmenopausal symptoms or birth control pills.
Pregnancy or having recently given birth, especially by C-section.
Varicose veins, which are swollen, twisted, painful veins.
SOURCES: Society for Vascular Surgery: "Deep Vein Thrombosis (DVT)." MedlinePlus: "Medical Encyclopedia: Deep vein thrombosis." American Academy of Family Physicians: "Deep Vein Thrombosis: What You Should Know." American Academy of Orthopaedic Surgeons: "Deep Vein Thrombosis." WebMD Medical Reference from Healthwise: "Deep Vein Thrombosis - What Increases Your Risk."