Deep vein thrombosis (DVT)

Deep vein thrombosis (DVT) occurs when a blood clot forms in a deep vein, usually in the legs. Part of the clot can break off and travel to the lungs, causing a pulmonary embolism (PE) — a potentially life-threatening emergency. Together, DVT and PE are known as venous thromboembolism (VTE).

Risk rises with immobility, surgery, cancer, pregnancy, hormone use, and inherited clotting disorders. Prompt diagnosis and anticoagulation prevent extension of the clot and embolization. Many people recover fully; some develop long-term leg symptoms (post-thrombotic syndrome).

DVT symptoms may include:

• Swelling in one leg (or arm, if that is the site)
• Pain or tenderness, often starting in the calf
• Warmth over the affected area
• Red or discolored skin
• Visible surface veins

Some DVTs cause no noticeable symptoms. Symptoms of pulmonary embolism include sudden shortness of breath, chest pain that worsens with deep breathing, rapid pulse, coughing (sometimes with blood), and lightheadedness — these require emergency care.

Clots form when blood flow is sluggish, the vessel wall is injured, or the blood is hypercoagulable (Virchow’s triad). Common contributing situations include:

• Prolonged immobility (hospitalization, long flights, bed rest)
• Recent surgery or trauma, especially orthopedic
• Cancer and some cancer treatments
• Pregnancy and the postpartum period
• Estrogen-containing contraceptives or hormone therapy
• Inherited thrombophilias (Factor V Leiden, prothrombin mutation, antithrombin deficiency, protein C or S deficiency)
• Antiphospholipid syndrome
• Older age, obesity, smoking, and prior VTE

Major risk factors include prior VTE, active cancer, major surgery or trauma, hospitalization, pregnancy, estrogen therapy, inherited clotting disorders, advanced age, obesity, smoking, heart failure, and inflammatory conditions. Risk multiplies when several factors coexist.

Important complications:

• Pulmonary embolism — can cause death if large or untreated
• Post-thrombotic syndrome — chronic leg pain, swelling, skin changes, and ulcers from valve damage and venous hypertension
• Chronic thromboembolic pulmonary hypertension (rare, after PE)
• Bleeding related to anticoagulant treatment

Prevention strategies include:

• Early mobilization after surgery or illness
• Prophylactic anticoagulation in high-risk hospitalized or postoperative patients
• Mechanical methods (compression stockings, intermittent pneumatic compression) when appropriate
• On long trips: stand and walk periodically, perform seated calf exercises, stay hydrated, and consider graduated compression stockings if at elevated risk
• Do not smoke; maintain a healthy weight
• Discuss VTE risk when starting estrogen therapy or planning pregnancy if you have additional risk factors

Evaluation uses clinical probability assessment (Wells score), D-dimer blood testing, and imaging:

• Compression ultrasound — first-line imaging for suspected leg DVT
• CT pulmonary angiography or ventilation-perfusion scan for suspected PE
• D-dimer — useful to rule out VTE in low-probability patients when negative
• Additional tests for underlying causes in unprovoked or recurrent VTE (selectively, based on age and context)

Seek medical care promptly for unexplained leg swelling and pain. Call emergency services for symptoms of pulmonary embolism (sudden dyspnea, chest pain, coughing blood, fainting).

Mainstay of treatment is anticoagulation:

• Direct oral anticoagulants (apixaban, rivaroxaban, edoxaban, dabigatran) or warfarin, or low-molecular-weight heparin — choice depends on cancer status, kidney function, pregnancy, cost, and preference
• Duration: typically at least 3 months for provoked VTE; longer or indefinite therapy for unprovoked, recurrent, or ongoing high-risk situations
• Thrombolysis or thrombectomy in selected massive PE or severe iliofemoral DVT with limb threat
• Inferior vena cava filters when anticoagulation is contraindicated (temporary filters preferred when possible)
• Compression therapy and exercise for post-thrombotic symptoms

Bleeding risk is balanced against clotting risk at every stage of care.

While on treatment:

• Take anticoagulant exactly as prescribed; do not skip doses
• Know the signs of bleeding and when to seek help
• Elevate the leg and use compression stockings if recommended
• Stay active within medical advice; avoid prolonged immobility
• Inform all clinicians and dentists that you are anticoagulated
• Keep follow-up appointments for monitoring and decisions about duration of therapy

Bring:

• Description of swelling, pain, and any breathing symptoms
• Recent surgeries, hospitalizations, travel, or pregnancies
• Personal and family history of blood clots or clotting disorders
• Complete medication list, including hormones
• Questions about anticoagulant choice, duration, and activity restrictions