Version July 2025
| Hereditary thrombophilias* | Comments |
| Factor V Leiden¶ | |
| Prothrombin G20210A¶ | |
| Protein S deficiency | Borderline low-normal values are also associated with an increased risk of VTE. The risk is lower than a true deficiency (ie, the relationship is linear). |
| Protein C deficiency | Borderline low-normal values are also associated with an increased risk of VTE. The risk is lower than a true deficiency (ie, the relationship is linear). |
| Antithrombin deficiency | |
| Others (eg, heparin cofactor II deficiency, dysfibrinogenemia, factor XII deficiency, supernumerary sex chromosome aneuploidies, other genetic variants) | The association between venous thrombosis and these inheritable coagulable disorders is less robust than other inheritable disorders. |
| Acquired conditions | Comments |
| Previous thromboembolism¶ | Recurrence may affect the same location, although recurrent DVT may be in the contralateral rather than ipsilateral leg. |
| Active malignancy¶ | Patients with active malignancy (ie, require treatment) are at the highest risk, especially pancreatic carcinoma and myeloproliferative neoplasms (eg, polycythemia vera and essential thrombocythemia). Risk is highest at initial hospitalization, onset of chemotherapy, and disease progression. Select drugs also place the patients at risk. Catheters in the upper extremity increase the risk for upper extremity DVT. Recurrence is also greater than in noncancer patients despite therapeutic anticoagulation. |
| Surgery¶ | Surgeries with the highest risk include major vascular, orthopedic (especially total hip and knee replacement), pelvic, neuro-, and cancer surgery. |
| Major trauma¶ | Patients with major trauma are at greatest risk, although patients with mild trauma may also have a small increased risk (eg, trauma not requiring surgery, a plaster cast, hospitalization, or extended bed rest at home for at least 4 days). |
| Older age (≥65 years)¶ | |
| Immobilization/limb immobility¶ | Immobilization promotes venous stasis. The condition associated with immobilization may increase the risk further (eg, heart failure, femoral fracture). |
| Pregnancy¶ | |
| Chronic inflammatory bowel disease and chronic liver disease | |
| Cardiovascular disease/risk factors and heart failure¶ | Risk may be greatest in those hospitalized and those with right heart failure. |
| Obesity | |
| Smoking | |
| Drugs | |
| Hormonal therapies¶ | Common agents include oral and transdermal contraceptive use, oral hormone replacement therapy, tamoxifen. |
| Others | Other agents include bevacizumab and tranexamic acid. Recent glucocorticoid use and antidepressants may also be associated with increased risk, but data are limited. |
| Antiphospholipid syndrome | Patients are at risk of venous and arterial thrombosis. |
| Kidney disease | This includes patients with end-stage kidney disease, nephrotic syndrome¶, and kidney transplant. |
| Hematologic conditions | |
| HIT and HIT-like and VITT-like variants | |
| Hyperviscosity syndromes | This includes hyperfibrinogenemia, hypergammaglobulinemia, myeloproliferative syndromes, hyperleukocytosis, sickle cell disease. |
| Paroxysmal nocturnal hemoglobinuria | |
| Miscellaneous | This includes patients with hyperhomocysteinemia, polycystic ovary syndrome, ovarian hyperstimulation syndrome, rheumatoid arthritis, central catheters, superficial vein thrombosis, COVID-19, and others (refer to UpToDate text for details). |
| Anatomic abnormalities | This includes varicose veins, Paget-Schroetter syndrome (thoracic outlet compression), May-Thurner syndrome (iliac vein compression), or inferior vena cava agenesis, hypoplasia, or malformation. |
| Other clotting factors and chemokines | Abnormal levels of some clotting factors and chemokines (eg, factors VIII, IX, and XI; thrombin-activatable fibrinolysis inhibitor; and interleukin 8) and non-O blood type have been associated with an increased thrombotic risk. |
COVID-19: coronavirus disease 2019; DVT: deep vein thrombosis; HIT: heparin-induced thrombocytopenia; VITT: vaccine-induced immune thrombotic thrombocytopenia; VTE: venous thromboembolism.
* More than one inheritable disorder can exist in a given patient or occur together with acquired risk factors to augment the risk of thrombosis.
¶ Common disorder.
