It is important to note that the hard sclerothrombus formed at the injection site is part of the process, however ‘soft’ thrombi may result after sclerotherapy due to trapped blood in the remainder of the vein.

Once sclerosed the flow through the vein stops and any trapped blood will form a soft thrombus. Thrombi can be minimised by using the empty vein technique followed by immediate compression, however it is difficult to adequately compress some veins and some blood is frequently trapped.

Treatment is uncomplicated and it is best to drain the blood when the thrombus has liquefied (approx 2 weeks). The clot can be drained at the follow up (2-4 weeks) via a small incision or easily aspirated using a needle and syringe.