According to WebMD, deep vein thrombosis is caused by a blood clot forming in a vein deep inside the muscle tissue. This is often prompted by surgery that reduces blood flow to a body part, but can it also be caused by injuries, diseases and lifestyle factors.
DVT occurs after surgery because surgical procedures often cause tissue debris, protein and fats to move into veins, reports WebMD. Vein walls can also become damaged, which may release blood-clotting substances. Common lifestyle factors that cause DVT include frequent and lengthy sitting or inactivity, long plane flights or long car trips, being overweight, use of birth control pills or patches, and smoking.
Other factors known to cause DVT include having a history of pulmonary embolism, inherited conditions that increase blood clotting, and paralysis or inactivity from a spinal cord injury, notes WebMD. Use of hormone therapy, including that used for postmenopausal symptoms, is a known cause, particularly if the person is a smoker. Pregnancy or having recently given birth, varicose veins, a history of heart attack, stroke or congestive heart failure, and inflammatory bowel disease all increase the risk of DVT.
WebMD states that rare causes of DVT include cancer near a vein, having a pacemaker or other implanted device for certain heart conditions and having a catheter inserted into a vein. The risk of developing the condition increases with age, and diagnosis is more common in people over the age of 60.