While most of us have heard of deep vein thrombosis (DVT), you may not have heard of a similar condition called superficial vein thrombosis (SVT).
Superficial vein thrombosis (SVT) is a condition where a vein just under the skin forms a blood clot. It is also sometimes referred to as phlebitis or superficial thrombophlebitis. The vein and surrounding area become painful, red, and swollen. The inflammation may spread along the vein up and down the leg. Without treatment, the clot can extend to involve much larger and deeper veins in the limb, and these clots can spread to the lungs. Superficial vein thrombosis (SVT) is therefore a potentially serious problem which needs careful assessment and treatment.
Superficial vein thrombosis most frequently arises in pre-existing varicose veins, but any vein can be affected. There is a well-recognised link with cancer, in that patients with active cancer often develop SVT. It is, however, rare for SVT to be the first presenting symptom of a new, undiagnosed cancer.
Superficial vein thrombosis is often mistakenly considered to be an unimportant, minor, self-limiting condition and is frequently not properly treated. The reason that SVT should be taken seriously is that a significant proportion of patients go on to develop more serious forms of blood clot, such as deep vein thrombosis or pulmonary emboli (clots in the lung). The risk of such an event remains five times higher than normal for more than five years after the event.
It is essential to perform a duplex (Doppler-ultrasound) scan to diagnose SVT. This is because over a quarter of patients turn out to have an associated deep vein thrombosis (DVT), which cannot be detected by clinical examination alone. Furthermore, some 17% of these DVTs are in the OPPOSITE leg, so it is vital to check both sides.
Clots affecting the lungs are less common, but they still occur in 2-7% of patients.
It is advisable to assess the risk of progression for every patient and try to target the treatment with anticoagulant medication significantly reduces the risk of superficial vein thrombosis progressing to a more serious blood clot such as a deep vein thrombosis or pulmonary embolus.
Those patients whose problem affected a long-standing varicose vein should have the culprit vein treated at the earliest opportunity once the acute problem has settle.