A population-based case-control study performed revealed that family history of dvt is a risk factor for a first dvt.  Blood samples and information about family history and environmental triggers were collected from 1,605 patients with a first dvt and 2,159 control subjects, 31.5% of patients and 17.3% of the controls reported having one or more first-degree relatives with a history of dvt.  A positive family history increased the risk of dvt more than 2-fold, and up to 4-fold when one or more relatives was affected.  

The risk also increased when a family history of dvt was also present with other genetic or environmental risk factors.  For those with a family history, a genetic, and an environmental risk factor, the risk of dvt was increased 64- fold compared to those without risk factors or a family history.  Overall, it is important to pay attention to a patient's family history of dvt, as it may be beneficial in risk assessment for patients who are undergoing surgery.  Patients who have a family of dvt and are in a hypercoaguable state from surgery, may benefit from extra prophylaxis in the prevention of dvt.