Deep vein thrombosis

Disease Description (Causes and Symptoms)

• Definition and pathophysiology: Deep vein thrombosis (DVT) is a condition in which a blood clot forms mainly in the deep veins of the legs, partially or completely blocking venous blood flow. Virchow’s triad (venous stasis, hypercoagulability of the blood, and vascular endothelial injury) are the main contributing factors. If part of a deep vein clot breaks off and travels to the pulmonary artery, life-threatening pulmonary embolism (PE) may occur; chronically, chronic venous ischemia (post-thrombotic syndrome) may develop due to loss of venous valve function.
• Main causes: Prolonged immobility (surgery, hospitalization, long-distance travel), cancer, pregnancy, hormonal medications (oral contraceptives), inherited or acquired thrombophilia (coagulation factor abnormalities), trauma, venous catheters, obesity, smoking, and others.
• Main symptoms: Swelling and pain in one leg (especially the calf), skin redness and warmth, cyanosis or changes in skin color, and symptoms related to peripheral ischemia; sudden shortness of breath, chest pain, or fainting may indicate pulmonary embolism and require emergency evaluation.

Treatment Methods

• Treatment goals: Prevent pulmonary embolism, inhibit clot extension/reformation, and minimize chronic complications (post-thrombotic syndrome).
• Medication treatment (standard):
  • Initial anticoagulation: Low-molecular-weight heparin (LMWH), unfractionated heparin (UFH), or direct oral anticoagulants (DOACs; e.g., rivaroxaban, apixaban). Intravenous heparin may be preferred in hemodynamically unstable PE or in high-risk patients.
  • Maintenance/oral treatment: DOACs (rivaroxaban, apixaban, edoxaban, dabigatran) or warfarin (Coumadin). DOACs are often the first choice because they require less monitoring and are effective (they are limited in some situations, such as renal failure, pregnancy, and mechanical heart valves).
  • Treatment duration: Provoked DVT (e.g., after surgery) is generally treated for 3 months; in cases that are unprovoked or of unclear cause, or when the risk of recurrence is high, treatment is given for ≥3 months (with consideration of indefinite extension). The treatment duration requires an individualized risk-benefit assessment.
• Invasive/procedural treatment:
  • Thrombolysis (when acute large iliac or femoral vein occlusion causes leg ischemia or severe symptoms): Catheter-directed thrombolysis ± mechanical removal may be considered.
  • Thrombectomy: Used selectively.
  • Inferior vena cava filter (IVC filter): Inserted on a limited basis when anticoagulation is contraindicated or emboli continue to occur despite anticoagulation.
• Conservative and lifestyle management:
  • Early ambulation and joint exercises are recommended (when possible).
  • Elevate the legs and maintain adequate fluid intake.
  • Compression/elastic stockings: They may help relieve symptoms during the acute phase, but their effectiveness in preventing post-thrombotic syndrome varies among studies. Use them for symptom relief or as directed by a doctor.
• Precautions (during treatment):
  • Assess the risk of bleeding (active bleeding, recent hemorrhagic stroke, etc.).
  • Adjust medication doses according to kidney and liver function.
  • Use caution regarding drug interactions (especially with warfarin) and medication selection during pregnancy and breastfeeding.
  • Management when stopping anticoagulants and around surgery (a plan for stopping, substituting, or transitioning anticoagulants is necessary).

Pre-Appointment Checkpoints (Items to Bring and Example Questions)

• Items to prepare/bring:
  • A list of all medications and supplements currently being taken (including doses and times of administration)
  • Medical history: Previous DVT/PE, bleeding disorders, history of surgery or trauma
  • Possibility of pregnancy/whether currently pregnant and whether breastfeeding
  • Recent test results (blood tests, kidney function tests, previous ultrasound, CT, and clot test results)
  • When symptoms began and how they have changed (when they started, which leg, aggravating factors, etc.)
  • Lifestyle habits (long-distance travel or prolonged sitting, occupation, smoking, weight)
• Show the doctor directly during the appointment:
  • Medication list, test records (especially any INR results), photographs (leg swelling and skin changes)
• Examples of questions to prepare in advance for the doctor (including brief examples):
  • What is the likelihood of side effects or bleeding from the anticoagulant I am currently taking?
  • How long should I take anticoagulants? What should I do if my risk of recurrence is high?

Examples of General Questions to Ask the Doctor

• Which anticoagulant do you recommend in this case, and why?
• What should I do if bleeding occurs while taking an anticoagulant (when should I go to the emergency room)?
• What medications, foods, or activities should I avoid while taking the medication (e.g., strenuous exercise, alcohol)?
• How does anticoagulant treatment change if I become pregnant or am planning to become pregnant?
• What lifestyle changes should I make to reduce the risk of recurrent clots?

Examples of Disease-Specific Questions

• How does the location of my clot (e.g., iliac vein, femoral vein, or calf vein) affect the risk of pulmonary embolism or treatment decisions?
• I have cancer (or an inherited thrombotic disorder, prolonged hospitalization, etc.), so I am told that my risk of recurrence is high. Should the duration of anticoagulant treatment be extended? Is additional prevention, such as an IVC filter, necessary?