- Venous Stasis (Slow Blood Flow):
- Prolonged Immobility: Common during long periods of sitting (e.g., long flights, car rides), bed rest (e.g., after surgery or illness), or paralysis.
- Major Surgery: Especially orthopedic surgeries of the hip or knee, abdominal surgery.
- Hospitalization: Reduced mobility during illness or recovery.
- Obesity.
- Heart Failure: Reduced pumping efficiency can lead to slower blood flow in veins.
- Hypercoagulability (Increased Clotting Tendency):
- Inherited Thrombophilias: Genetic conditions that increase clotting risk (e.g., Factor V Leiden mutation, prothrombin gene mutation, deficiencies of antithrombin, Protein C, or Protein S).
- Cancer: Many types of cancer increase clotting factors or damage blood vessels, raising DVT risk. Chemotherapy can also increase risk.
- Pregnancy and Postpartum Period: Hormonal changes and increased pressure on pelvic veins. The risk is highest in the postpartum period.
- Estrogen-Containing Medications: Oral contraceptives, hormone replacement therapy.
- Antiphospholipid Syndrome (APS): An autoimmune disorder that directly increases clotting risk.
- Inflammatory Bowel Disease (IBD): Chronic inflammation can contribute to hypercoagulability.
- Sepsis/Severe Infection.
- Dehydration.
- Endothelial Injury (Damage to the Blood Vessel Lining):
- Trauma: Direct injury to a vein.
- Surgery: Especially orthopedic or abdominal surgery.
- Previous DVT: Damaged vein walls from a prior clot increase the risk of recurrence.
- Central Venous Catheters: Lines placed in large veins for medication or fluid administration can irritate the vein lining.
- Varicose Veins: While superficial, severe varicose veins can sometimes be associated with DVT.
- Swelling: In the affected limb (leg, ankle, or foot), often unilateral (one-sided). The swelling may be pitting (indentation remains after pressing).
- Pain or Tenderness: In the affected limb, often described as a cramp or soreness, or a deep ache. May worsen with walking or standing.
- Warmth: In the skin over the affected area.
- Redness or Discoloration: Of the skin over the affected area.
- Visible Veins: Swelling of superficial veins.
- Increased Leg Circumference: Compared to the unaffected leg.
- Symptoms of Pulmonary Embolism (PE) - Medical Emergency: If a DVT travels to the lungs.
- Sudden shortness of breath.
- Chest pain (sharp, stabbing, often worse with deep breath or cough).
- Rapid heart rate.
- Unexplained cough (may be bloody).
- Dizziness or lightheadedness, fainting.
- Anxiety.
- Medical History and Physical Exam: The doctor will ask about symptoms, risk factors for DVT, and family history. The exam involves checking for swelling, tenderness, warmth, and skin changes in the affected limb.
- D-dimer Blood Test:
- A blood test that measures a substance released when a blood clot dissolves.
- A negative D-dimer test can often rule out DVT in low-risk patients (high sensitivity).
- However, a positive D-dimer can indicate a clot but can also be elevated in many other conditions (e.g., infection, surgery, pregnancy, cancer), so it's not specific for DVT.
- Duplex Ultrasound (Venous Ultrasound):
- The most common and effective diagnostic test for DVT.
- Uses sound waves to visualize blood flow in the veins and detect blockages (clots). The inability to compress a vein with ultrasound probe pressure is a key sign of a clot.
- CT Venography or MR Venography:
- More detailed imaging tests used when ultrasound is inconclusive or if clots are suspected in veins in the abdomen or pelvis.
- Involve injecting contrast dye to highlight the veins.
- Venography: (Less common) An invasive X-ray test using contrast dye injected directly into a vein. Considered the gold standard but rarely used now due to less invasive methods.
- Anticoagulant Medications (Blood Thinners):
- These medications do not dissolve existing clots but prevent new clots from forming and stop existing clots from growing larger, allowing the body's natural clot-dissolving mechanisms to work.
- Initial Treatment (typically 5-10 days):
- Low Molecular Weight Heparin (LMWH) Injections: (e.g., enoxaparin) or unfractionated heparin (IV for severe cases).
- Direct Oral Anticoagulants (DOACs) or Factor Xa Inhibitors: (e.g., rivaroxaban - Xarelto, apixaban - Eliquis, edoxaban - Savaysa, dabigatran - Pradaxa) Can sometimes be started immediately without initial heparin.
- Long-Term Treatment (typically 3-6 months or longer):
- Warfarin (Coumadin): Requires regular INR blood monitoring.
- DOACs: Increasingly preferred due to convenience and no need for routine monitoring.
- The duration of anticoagulation depends on whether the DVT was provoked (e.g., by surgery, trauma) or unprovoked, and the presence of underlying thrombophilias.
- Thrombolysis (Clot-Busting Drugs):
- (Rarely used) Medications that actively dissolve blood clots.
- Reserved for very severe DVTs (e.g., involving large veins, causing limb-threatening ischemia) or large PEs, due to a high risk of bleeding.
- Can be given systemically (IV) or catheter-directed (delivered directly to the clot).
- Inferior Vena Cava (IVC) Filter:
- A small filter placed in the large vein in the abdomen (inferior vena cava) to catch blood clots traveling from the legs to the lungs.
- Used for patients who cannot take anticoagulants (due to bleeding risk) or who develop recurrent PEs despite anticoagulation.
- Many are now retrievable.
- Compression Stockings:
- Graduated compression stockings can help reduce leg swelling and prevent or alleviate symptoms of post-thrombotic syndrome (PTS), a long-term complication of DVT.
- Lifestyle Modifications and Risk Factor Management:
- Early Ambulation: Get up and move as soon as possible after surgery or illness.
- Regular Exercise: To improve blood flow.
- Maintain a Healthy Weight.
- Quit Smoking.
- Stay Hydrated.
- Avoid Prolonged Immobility: During long travel, take breaks to walk around, stretch legs, or wear compression stockings.
- Manage Underlying Conditions: (e.g., cancer, autoimmune diseases).