Deep vein thrombosis (DVT) occurs when a blood clot forms in a deep vein, typically in the leg. While initial treatment manages the clot, many individuals experience persistent leg swelling long after the acute phase. Understanding its underlying causes can help clarify why this often happens. This article explains why leg swelling often persists after a DVT.
Initial Swelling and Resolution
When a deep vein thrombosis occurs, the blood clot obstructs blood flow back to the heart. This blockage causes blood to pool in the affected limb, leading to swelling. The leg may also experience pain, tenderness, and warmth, along with a reddish or discolored appearance.
Initial DVT treatments, like anticoagulant medications, prevent clot growth and reduce the risk of it traveling to the lungs. These medications do not directly dissolve the clot but allow the body to break it down over weeks to months. As the clot resolves and blood flow improves, the acute swelling typically begins to subside, with significant improvement often seen within three to six months. However, in some cases, the initial DVT can cause lasting damage, leading to prolonged swelling.
Understanding Post-Thrombotic Syndrome
Persistent leg swelling after a DVT is a long-term complication called post-thrombotic syndrome (PTS). It develops when deep veins in the leg are damaged by the blood clot and inflammation. PTS affects approximately 20% to 50% of individuals within two years of their DVT diagnosis.
PTS is also sometimes referred to as postphlebitic syndrome or venous stress disorder. It is a form of chronic venous insufficiency resulting from DVT. It can manifest weeks or months after the DVT, with incidence increasing for many years, even up to 10 to 20 years later.
How PTS Causes Swelling
The primary mechanism by which PTS causes ongoing swelling involves damage to the one-way valves located inside the leg veins. These valves open to allow blood flow towards the heart and close to prevent backward flow due to gravity. A blood clot’s inflammation and scarring can weaken or damage these valves, making them less effective or leaky.
This valvular dysfunction means that blood can pool in the lower leg veins, increasing the pressure within them, a condition known as venous hypertension. This pressure forces fluid to leak from veins into surrounding leg tissues. This fluid accumulation manifests as chronic swelling. Persistent inflammation and scarring within vein walls further impair fluid drainage, leading to long-term swelling.
Recognizing Other Symptoms of PTS
While swelling is a prominent feature, post-thrombotic syndrome often presents with a range of other symptoms that arise from the chronic venous hypertension and inflammation. Individuals may experience persistent pain, heaviness, aching, or cramping in the affected leg. These sensations are often worse after prolonged standing or walking and may improve with rest or leg elevation.
Other PTS indicators include itching, tingling, or unusual leg sensations. Skin over the affected area may also change, developing reddish or brownish discoloration, especially around the ankle. In advanced cases, skin can become hardened, thickened, or dry and scaly. Some individuals may develop painful open sores called venous ulcers, typically near the ankle.
Approaches to Managing Persistent Swelling
Managing persistent leg swelling from PTS involves strategies to reduce venous pressure and improve blood flow. Compression therapy, most commonly using graduated compression stockings, is a key part of management. These stockings apply external pressure, tighter at the ankle and looser higher up, counteracting blood pooling and reducing fluid leakage.
Regular leg elevation, especially during rest, also decreases swelling by promoting fluid drainage to the heart. Consistent physical activity, especially calf muscle exercises, is beneficial. Calf muscle contractions act as a pump, assisting veins in pushing blood upwards against gravity. Additionally, diligent skin care is important to maintain skin integrity and prevent complications like infections or skin breakdown, especially if skin changes or ulcers are present. Working closely with healthcare professionals is important to develop a personalized management plan for PTS.