Superficial thrombophlebitis is inflammation of a vein just under the skin, usually in the leg. A small blood clot also commonly forms in the vein, but is usually not serious. The condition usually settles and goes within 2-6 weeks. Treatments can ease pain or discomfort. Superficial thrombophlebitis is different to, and much less serious than, deep vein thrombosis. However, in a small number of cases, complications can occur with superficial thrombophlebitis including extension of the blood clot further up the vein. If the clot extends to where the superficial and deep, larger veins join, a deep vein thrombosis can develop.
A vein is a blood vessel that takes blood towards the heart. If a vein becomes inflamed, a blood clot commonly forms inside the inflamed portion. So, the term thrombophlebitis is used to mean an inflamed vein, with or without a small blood clot inside the vein. Thrombophlebitis is commonly just called phlebitis.
The superficial veins are the ones that you can often see or feel just under the skin. Most bouts of superficial thrombophlebitis occur in a leg vein, but any superficial vein can be affected. A typical site is in a varicose vein in a leg. Varicose veins are common, particularly in pregnant women. Superficial thrombophlebitis is not usually serious, but complications can sometimes occur (see below).
Note: this leaflet does not deal with inflammation or thrombosis of deep veins. The deep veins are larger, pass through the muscles in your arms and legs, and you cannot see or feel them. Some people get confused between superficial thrombophlebitis and deep vein thrombosis. They are quite different. A deep vein thrombosis (DVT) is more serious.
See separate leaflet called Deep Vein Thrombosis for more detail.
Many cases occur for no apparent reason. A slight injury to the vein may trigger the inflammation in some cases.
There are a number of risk factors that make it more likely for inflammation to develop in a vein:
Swelling, redness, and tenderness along a part of the vein are the usual symptoms. You may develop a fever (high temperature). If a blood clot develops inside the inflamed part of the vein, the vein may then feel hard or knobbly. The blood clot is usually of little concern, as it is small. There are other veins which carry the blood, and bypass the blocked vein.
When the inflammation settles, a persistent darker area of skin (hyperpigmentation) may remain over the affected vein. A small firm lump may also persist below the skin. This may be tender to the touch for some time.
Your doctor is usually able to diagnose superficial thrombophlebitis by talking to you and examining the affected area. Investigations are not usually needed, especially if you have one of the risk factors for superficial thrombophlebitis (see above). However, if your doctor is concerned that you may have a DVT (see below), they may advise that you have some tests to exclude this. This usually means a special ultrasound scan of the affected area to look for any clots in the deep veins.
If you have recurrent bouts of thrombophlebitis, especially if you have no real risk factors for superficial thrombophlebitis, your doctor may suggest some tests to check that you do not have any problems with the clotting of your blood. They may also suggest other tests to look for more rare causes of recurrent superficial thrombophlebitis (see below).
Most bouts of superficial thrombophlebitis last for 3-4 weeks. If they are associated with varicose veins, they are likely to recur. No treatment may be needed if the symptoms are mild. One or more of the following treatments may be advised, depending on your symptoms and the severity of the condition:
If varicose veins are the source of the problem, once the inflammation has settled, you may wish to consider treatment to remove the varicose veins. See your doctor for advice. There is another leaflet that discusses varicose veins in more detail.
If your doctor feels that you may have a DVT or be at high risk of developing one, they may suggest that you are referred either to the hospital or to a special DVT clinic so that you can have any investigations or treatment necessary (see above). Sometimes, prophylactic (just in case) treatment may be given to people who have superficial thrombophlebitis and may be at high risk of developing a DVT. This involves injection of a drug to thin the blood.
The inflammation and pain usually settle within a few weeks. Most people make a full recovery. The possible complications listed below are uncommon, but are listed to give guidance on what to look out for. See a doctor as soon as possible if you suspect that a complication is developing.
Sometimes the affected vein becomes infected. The pain may then become worse, and the redness spreads. You are likely to feel generally unwell. Infection is more common in someone who has had a drip inserted for a long period, in people who abuse 'street drugs' or in people with a weakened immune system. Antibiotics are needed to treat the infection. If the infection is severe, you may need to be admitted to hospital for antibiotics (given directly into a vein). Rarely, infection in a vein becomes severe and may spread to other areas of the body.
In some cases, the blood clot can extend further up the vein. If the clot extends to where the superficial and deep veins join, a DVT can develop. This is more likely if the superficial thrombophlebitis is in the upper thigh or the groin, near to where the superficial veins and the deep veins of the leg meet. There is a similar meeting point of superficial and deep veins at the crease behind the knee. It is also more likely to occur if superficial thrombophlebitis develops in a previously normal vein (not a varicose vein), if you have had a DVT before, or if you are immobile for some reason.
Another leaflet deals with DVT. Very briefly, see a doctor urgently if:
When a DVT leads to thrombophlebitis, there is an increased risk of developing further deep vein thromboses and possibly clots on the lung - pulmonary embolism (PE).
It is common for people with varicose veins to get recurrent bouts of superficial thrombophlebitis. However, for a small number of people this may be the first sign of a more serious condition such as cancer or polyarteritis nodosa (a rare condition where there is patchy inflammation of the walls of the arteries). This is more likely if the bouts occur at different sites, or in different veins in someone without varicose veins.
Tests may be advised if there is no obvious explanation for recurring bouts of superficial thrombophlebitis.