Post-thrombotic syndrome: long-term leg symptoms after a DVT

A deep vein thrombosis (DVT) is a blood clot in a deep vein, most often in the leg. After treatment with anticoagulant medicines, which stop the blood clotting as quickly as usual, the clot is gradually broken down. Guy's and St Thomas' explains that sometimes some blockage remains, and that veins scarred with old clots and damaged valves can cause post-thrombotic syndrome. Valves help blood return to the heart, so when they are damaged blood pools in the lower leg.

The same trust describes a related problem, chronic venous insufficiency, in which leg veins do not allow blood to flow back up to the heart as fast as it should. Some of the symptoms are shared, and chronic venous insufficiency can also affect people who have never had a DVT.

The symptoms of PTS are different for each person. Guy's and St Thomas' lists the following possibilities. They are often worse after long periods of sitting or standing and may ease with walking or raising the leg.

• Long-term pain, aching and heaviness in the leg.

• Itching and pins and needles.

• Swelling (oedema) of the leg.

• Varicose veins.

• Patches of darker skin around the ankle and lower leg, which may be harder to see on brown or black skin.

• In severe cases, breaks in the skin (ulceration), particularly around the ankles.

Guy's and St Thomas' says the risk is higher if you have had more than one DVT (recurrent DVT) or if your first DVT was extensive and affected veins in the pelvis and groin. It adds that the risk of another DVT depends on the original cause, and a haematologist will investigate if recurrent clots suggest an underlying clotting problem.

Ask your clinician what can be done to lower the chance of long-term problems after a first DVT. Staying active and keeping to a healthy weight are sensible general measures, though the sources used here do not claim that they prevent PTS.

PTS is diagnosed mainly from the history and examination: previous DVT, typical symptoms and signs in the affected leg. Guy's and St Thomas' says a clinical nurse specialist normally uses a scoring tool called the Villalta score to measure how severe symptoms are.

It can be difficult to tell a new DVT from long-term effects. The trust advises telling your doctor about any sudden change in the affected leg, in which case they may check for a new clot with blood tests and an ultrasound scan, which is painless and shows blood flow in the leg and pelvis.

There is no cure for PTS and it is a long-term condition. Guy's and St Thomas' says the aims of treatment are to control or reduce symptoms and to reduce the risk of ulceration. Sometimes you may need a mixture of the options below, and all treatments have risks as well as benefits, which are explained before decisions are made.

Everyday habits make a difference. Keep moving rather than sitting or standing for long periods, raise the leg when resting, wear your stockings as advised, moisturise the skin and look after any minor skin breaks promptly. If you have severe symptoms that go untreated, Guy's and St Thomas' says this can lead to skin ulceration, particularly around the ankles, so seek advice early if the skin changes colour, hardens or breaks.

The trust's advice about travel after vein surgery is to avoid long-haul flights of more than 4 hours in the week before the operation and for 4 weeks afterwards. If you have had a stent, scans at regular intervals check that it stays open.

Chronic leg symptoms can affect mood, work and sleep. It is reasonable to tell your GP if they are having a significant impact, as support or a referral to a vascular or venous clinic may help.

The NHS says to call 999 or go to A&E if you have symptoms of DVT, such as pain and swelling, and feel short of breath or have chest pain, because blood clots can travel to the lungs, causing a pulmonary embolism that can be life-threatening. Do not drive yourself.

Contact your GP or clinic promptly if the leg becomes suddenly more swollen, red, hot or painful, because it may be a new clot, or if you develop an open sore that is not healing or signs of infection.

In the NHS, PTS is managed by your GP, anticoagulation or thrombosis clinic and, for more severe disease, a vascular or venous clinic where vascular doctors, haematologists and interventional radiologists review cases together.

A private vascular surgeon or haematologist may be sought for a second opinion or a quicker appointment, particularly when a venous stent is being considered. As these procedures need long-term follow-up with scans, ask who will be responsible for monitoring afterwards.