Post-Thrombotic Syndrome

Overview

Post-thrombotic syndrome is a long-term complication that can develop after a deep vein thrombosis (DVT), a blood clot in a deep vein, usually in the leg. After a clot, the affected vein and its valves can be damaged or partly blocked. This raises the pressure in the leg veins and interferes with normal blood flow back to the heart.

The result is a set of chronic symptoms in the affected leg, including swelling, aching, heaviness, and changes to the skin. Symptoms range from mild to disabling. Post-thrombotic syndrome is common after DVT, and while it cannot always be reversed, the right care can ease symptoms and prevent complications such as skin breakdown.

Symptoms

Symptoms affect the leg where the clot occurred and tend to worsen with standing or walking and improve with rest and elevation. They may include:

• Chronic swelling of the leg or ankle.
• Aching, heaviness, or fatigue in the leg.
• Cramping or a feeling of tightness.
• Itching or tingling.
• Skin changes, such as darkening, thickening, or a brownish discoloration around the ankle.
• Visible varicose veins.
• In severe cases, an open sore (venous ulcer), usually near the ankle, that is slow to heal.

Symptoms usually develop gradually in the months to years after a DVT.

Causes

Post-thrombotic syndrome is caused by lasting damage to a vein after a blood clot. After a DVT:

• The clot can scar and narrow or block the vein, slowing blood flow.
• The one-way valves that normally keep blood moving toward the heart can be damaged, allowing blood to pool and flow backward.
• This raises pressure in the veins of the leg, a state called venous hypertension.
• The increased pressure leads to fluid buildup, swelling, and changes in the skin and tissues over time.

The combination of blockage and faulty valves is what produces the chronic symptoms.

Risk Factors

Factors that increase the chance of developing post-thrombotic syndrome after a DVT include:

• A clot located higher up in the leg, such as in the thigh or pelvis.
• A repeat DVT in the same leg.
• Obesity.
• Persistent leg symptoms early after the clot.
• Not reaching adequate blood-thinning treatment in the early period after a DVT.
• Older age.

Preventing and properly treating DVT is the most important way to reduce the risk.

Diagnosis

Diagnosis is based mainly on the history of a previous DVT and the characteristic leg symptoms. Evaluation may include:

• Medical history and examination, looking for chronic swelling, skin changes, and other signs in a leg with a prior clot.
• Scoring tools that grade symptoms and signs to judge severity.
• Ultrasound of the leg veins to assess blood flow, look for valve problems or remaining blockage, and rule out a new clot.
• Other imaging in selected cases to map the veins before any procedure.

Ruling out a new DVT is important, since a fresh clot needs urgent treatment.

Treatment

There is no cure that reverses the vein damage, so treatment focuses on relieving symptoms and preventing complications:

• Compression stockings, the mainstay of treatment, which reduce swelling and ease aching by supporting the veins.
• Leg elevation and regular exercise such as walking to improve blood flow.
• Skin care and moisturizing to protect against breakdown.
• Wound care for venous ulcers, which may need special dressings and compression to heal.
• Weight management and treating other vein problems.
• In selected severe cases, procedures to open or support a blocked vein.

Continuing blood thinners as prescribed and preventing another clot are also important parts of long-term care.

Prevention

The best way to prevent post-thrombotic syndrome is to prevent and properly treat the blood clots that cause it:

• Take blood-thinning medication exactly as prescribed after a DVT.
• Follow up to make sure the clot is adequately treated.
• Use compression stockings if recommended.
• Stay active and move the legs, especially during long periods of sitting or travel.
• Maintain a healthy weight and not smoke.
• Seek prompt care for symptoms of a new clot.

When to See a Doctor

See a doctor if you have a history of a leg clot and develop ongoing swelling, aching, skin discoloration, or an open sore on the leg, so that symptoms can be managed and ulcers prevented or treated.

Seek urgent care if you have new or worsening leg swelling and pain, especially with warmth and redness, which could signal a new DVT. Call emergency services right away for sudden shortness of breath or chest pain, which may mean a clot has traveled to the lungs (pulmonary embolism).

Related Topics

Frequently Asked Questions

References

1. MedlinePlus, U.S. National Library of Medicine.
2. Mayo Clinic.
3. Centers for Disease Control and Prevention (CDC).
4. American Heart Association.