Provoking Factors for Deep Vein Thrombosis
Provoking factors for DVT are classified into transient and persistent risk factors, which fundamentally determine recurrence risk and guide anticoagulation duration decisions. 1
Classification Framework
DVT provoking factors exist on a continuum from fully reversible transient factors (lowest recurrence risk) to progressive persistent factors (highest recurrence risk). 1 The presence and type of provoking factor is the single most important variable influencing recurrent VTE risk after stopping anticoagulation. 2
Major Transient Risk Factors
These factors confer >10-fold increased risk of first DVT and reduce recurrence risk by half when they occurred within 3 months before the DVT: 1
- Surgery with general anesthesia >30 minutes 1, 2
- Hospital bed confinement ≥3 days (bathroom privileges only) with acute illness 1, 2
- Cesarean section 1, 2
Minor (Yet Important) Transient Risk Factors
These factors confer 3-10 fold increased risk of first DVT and reduce recurrence risk by half when they occurred within 2 months before the DVT: 1
- Surgery with general anesthesia <30 minutes 1, 2
- Hospital admission <3 days with acute illness 1, 2
- Estrogen therapy (oral contraceptives, hormone replacement therapy) 1, 2, 3
- Pregnancy or puerperium 1, 2, 4
- Confined to bed outside hospital ≥3 days with acute illness 1
- Leg injury with reduced mobility ≥3 days 1
Persistent Risk Factors
These factors remain ongoing and confer the highest recurrence risk: 1
Active cancer - the most important persistent provoking factor due to high incidence and strong association with recurrent thrombosis 1, 2. Cancer is considered active if it: (1) has not received potentially curative treatment, (2) shows evidence of recurrent/progressive disease, or (3) treatment is ongoing 1
Inflammatory bowel disease - associated with ≥2-fold increased risk of recurrent VTE 1, 2
Chronic inflammatory conditions including autoimmune diseases and chronic infections 1, 2
Additional Risk Factors for Long-Distance Travel
For travelers at substantially increased VTE risk (>4 hours travel), consider: 1
- Recent surgery 1
- History of VTE 1
- Postpartum status 1
- Active malignancy 1
- ≥2 risk factors combined (including hormone replacement therapy, obesity, or pregnancy) 1
Critical Clinical Distinctions
Intrinsic factors do NOT classify DVT as "provoked": Hereditary thrombophilias, male sex, and older age do not influence whether VTE is considered provoked or unprovoked, though they may affect individual recurrence risk stratification. 1, 2
Mixed presentations require careful assessment: Patients may have both transient and persistent factors simultaneously (e.g., surgery in a patient with metastatic cancer), placing them at intermediate recurrence risk between the two categories. 1
Comorbidities matter only if they increase VTE risk: The presence of conditions like rheumatoid arthritis only influences classification if they are sufficiently associated with recurrent VTE (≥2-fold increased risk). 1