Risk factors for DVT include any problem that alters the clotting system or alters blood flow in the deep veins.  These are broadly classified between acquired risk factors that enhance clotting and inherited thrombophilias.

The acquired risks are states that affect the clotting system indirectly and include chemical and physical factors that increased clotting.  

The inherited thrombophilias cause direct hypercoagulability because the affected proteins are integral parts of the clotting system.  

It should be noted that thrombus formation in the setting of inherited thrombophilic states is often precipitated by acquired risk factors which further increase the preexisting risk.  The following outline summarizes these factors:

1. Acquired Risk Factors

A. Vascular stasis (prolonged bed rest, prolonged sitting, travel)

B. Recent surgery (particularly orthopedic, vascular, and neurosurgical procedures) due to 

immobilization in the perioperative and postoperative time periods.

C. Malignancy

i. solid cancer (e.g., lung, pancreas, colorectal, kidney, prostate) related hypercoagulable state 

ii. myeloproliferative syndromes with elevated platelet counts (e.g., essential thrombocythemia) or increased hematocrit (e.g., polycythemia vera) 

iii. hyperviscosity from conditions such as IgM gammopathy (Waldenstrom’s macroglobulinema), multiple myeloma, or hyperleukocytosis from chronic myeloid leukemia [CML] blast phase or (acute myelogenous leukemia) AML

iv. Paroxysmal nocturnal hemoglobinuria (PNH)

D. Posttraumatic state, particularly major trauma of the lower extremity, pelvic fractures, and spinal cord injury.  Minor injuries are unlikely to cause risk for PE without a preexisting heritable thrombocytosis and occur within 2 to 3 weeks of injury.

E. Drugs/medications, including:

i. Oral contraceptives

ii. Hormone replacement therapy

iii. Testosterone

iv. Tamoxifen

v. Glucocorticoids (e.g., prednisone imparts a 1.5 - 3 x baseline risk)

vi. Antidepressants

vii. ADT for prostate cancer

F. Inflammatory illnesses, including:

     i. Anticardiolipin antibody

    ii. Inflammatory bowel disease

    iii. Rheumatoid arthritis

     iv. Asthma with local activation in lung of inflammatory cytokines (increased risk of PE, without DVT)

G. Cardiovascular disease associated risk factors (in addition to increased risk caused by primary cardiac disease (e.g., valvular disease, DVT risk factors are also associated with common cardiovascular risk factors):

i. Obesity (significant association with DVT: 2.5 x increase risk with BMI > 30)

ii. Dyslipidemia/metabolic syndrome

iii. Physical inactivity

iv. Smoking

v. Diabetes mellitus

vi. Alcohol use

H. Secondary polycythemia due to COPD or other causes of chronic hypoxemia

I. Pregnancy (as a result of mixed venous outflow obstruction in advanced pregnancy coupled with increased coagulation factors during 3rd trimester)

J. Renal disease (specifically with nephrotic syndrome)

K. Anatomic risks (e.g., varicose veins, prior DVT which increases risk for subsequent

DVT)

2. Inherited Thrombophilias, including:

   A. Activated protein C resistance (e.g., Factor V Leiden)

   B. Prothrombin mutation

    C. Protein C deficiency

   D. Protein S deficiency

    E. Antithrombin III deficiency

    F. Less common inherited thrombophilias (e.g., plasminogen deficiency, Factor XII deficiency,

inherited dysfibrinogens)

Deep Venous Thrombosis medical expert witness specialties include vascular surgery and hematology.

IF YOU NEED A DVT MEDICAL EXPERT, CALL MEDILEX AT (212) 234-1999.