Written by Mr Eddie Chaloner, consultant vascular surgeon
What is it?
|The mainstay of treatment is compression with stockings to try and squeeze the blood back up the leg the right way and careful attention to skin care with moisturisers.|
Post-thrombotic syndrome (PTS) is a problem that may occur in the leg after someone has suffered from a serious deep vein thrombosis (DVT).
A thrombosis occurs when a clot forms in the blood, blocking a blood vessel. If the blood clot occurs within a major vein, the condition is known as DVT. This usually happens in the leg veins.
Post-thrombotic syndrome can occur anytime after a DVT, depending on how bad the DVT was.
It causes swelling of the leg, aching and discomfort on standing, pain on walking and damage to the skin of the leg, particularly in the lower part.
Bad cases of PTS result in venous ulcers. PTS may not develop until several years after the initial DVT, as the symptoms often manifest slowly.
There is also a higher risk of a further DVT occurring as a result of subsequent clotting on an already damaged deep vein.
Why does post-thrombotic syndrome occur?
A bad DVT that is not promptly diagnosed and treated will cause damage to the valves and walls of the vein.
The valves' function is that to ensure that the blood goes up the leg to return to the heart. Vein valves are very delicate structures that get easily damaged. Once they are damaged, they cannot repair themselves.
The walls of the vein can also be damaged and scarred due to a DVT.
Scarred veins do not expand in the same way as normal veins, so when the flow of blood increases in the vein (as during walking), the veins do not stretch like they should and patients get a throbbing pain in the leg and swelling of the lower part of the leg.
If the veins are damaged, the blood tends to flow the wrong way – this is called reflux. The pressure in the veins in the lower part of the leg rises and this pressure creates the swelling and discomfort that patients feel.
Eventually if it goes on for long enough, it can damage the skin on the leg. The skin around the ankle becomes dry, itchy and discoloured. Eventually it becomes brown in colour and hard and leathery to feel.
Usually a minor abrasion then becomes a larger sore that does not heal, which is called a venous ulcer.
In extremely serious cases, the vein is so badly damaged that it completely blocks off so that no blood can flow through it at all.
This is the worst-case situation and causes the most severe form of post-thrombotic syndrome.
How can post-thrombotic syndrome be prevented?
The key to prevention of PTS is prompt diagnosis and treatment of DVT.
The sooner the DVT is diagnosed and treatment with anticoagulation medicines is given, the sooner the clot will dissolve. It is the inflammation caused by the clot that damages the valves and the vein walls.
Therefore, the sooner the clot dissolves, the less damage occurs to these structures, and the lower the risk is of PTS developing.
How can post-thrombotic syndrome be treated?
Unfortunately, there is no surgical treatment for PTS. This is because operating on the deep veins of the leg is usually unsuccessful. The results of surgical attempts to reconstruct deep veins valves have been disappointing in most parts of the world.
Venous ulcers are very difficult to treat after PTS. They require a lot of nursing care with four-layer compression bandaging to heal. Sometimes skin grafts are required. Some ulcers do not heal at all and become chronically infected and painful.
The mainstay of treatment is through compression with stockings to try and squeeze the blood back up the leg the right way. Patients are encouraged to pay careful attention to skin care with moisturisers.
Compression stockings are uncomfortable to wear and difficult to get on and off – for this reason the best way to treat PTS is to avoid getting it in the first place.
Who gets post-thrombotic syndrome?
Usually PTS occurs in patients who have had a really bad DVT after a major accident or lower limb surgery.
Almost always it is as a consequence of a DVT in the veins above the knee or in the pelvis.
Often it happens in patients who had a delay in the DVT being diagnosed, so that by the time of diagnosis the damage to the deep veins is already irreversible.
Minor DVT's in the veins below the knee don't usually cause PTS.
How does a patient know they have post-thrombotic syndrome?
Patients concerned about this issue should be referred to a vein specialist who will take a detailed history, examine the leg, and do a venous duplex ultrasound scan.
The scan should show if the deep veins of the leg are damaged and help the surgeon decide on the best treatment.
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