Spider veins, thread veins or dermal flares are very fine dilated veins which are very close to the surface of the skin. Like the larger varicose veins, heredity is a major factor as are hormonal changes which occur during pregnancy and the onset of periods. In some cases they are associated with deeper varicose veins but in others they can sometimes occur without any underlying varicose veins. Patients are recommended to undergo a Duplex scan in order to ensure there are no conditions which may be causing them. If surface veins are treated and varicose veins are present (even though they may not be visible) this will produce an unsatisfactory outcome and will lead to a recurrence of the thread veins.

Aching and throbbing can be associated with spider and thread veins. Symptoms that present with larger varicose veins may not completely disappear following surgery but will improve with microsclerotherapy (injection) treatment. This is the best form of treatment for small veins.