Surface Blood Clots: Causes, Risks, and Treatments

What are surface blood clots?

The current term for surface blood clots is superficial vein thrombosis (SVT). The terms phlebitis or superficial thrombophlebitis are also common. Surface blood clots are a common condition affecting up to 57% of patients with varicose veins. They may also affect some patients without varicose veins but prone to blood clots and those with cancer or having had recent surgery. SVT often develops and appears as an inflamed and painful area on the skin.

When SVT affects the main surface veins of the leg, rather than a small side-branch, it can be serious, with a higher risk of deep vein thrombosis (DVT). Blood clots caused by a DVT may break off and travel to the lungs, resulting in a life-threatening (pulmonary embolism, PE). Diagnosis of a serious SVT increases the risk of DVT and PE.

Illustration showing the development of a pulmonary embolism in the left lung caused by SVT — Pulmonary Embolism of the Left Lung

Investigation of surface blood clots

Ultrasound scan of the area affected by the SVT will confirm the diagnosis, determining whether the blood clot has extended to the deep veins as a DVT. When the blood clot is in the thigh portion of the main surface veins, and greater than 5cm in length, there is a higher risk of developing a DVT and PE. This risk may be as high as 20% if left untreated. Further attacks of SVT may occur in up to 10% of people, making treatment of the underlying condition, such as varicose veins, important. 1

Ultrasound Scan on Woman's Legs, Deep Vein Thrombosis — An Ultrasound Scan is Used to Confirm SVT.

Treatments

Blood thinners

Treatment of serious SVT has changed over the years. From simple pain relief, to urgent surgery and now the use of blood thinners. Blood thinners, such as Warfarin, Clexane, Pradaxa and Rivaroxaban, reduce the risk of blood clots progressing and DVT, PE and SVT from recurring. Each of the blood thinners has specific benefits and disadvantages. A patient’s general practitioner (GP) will usually prescribe a blood thinner, selecting the one most suited to the patient. In general, the course length of blood thinners for SVT is 4 to 6 weeks.

In New Zealand, Rivaroxaban is now one of the most commonly used tablet blood thinners. Patients with kidney impairment, those who are pregnant or breast feeding and some other groups of patients, cannot take Rivaroxaban and will need an alternative. A patient’s GP will recommend a suitable alternative.

Illustration Of Blood Thinner Medication. Used to Treat Superficial Vein Thrombosis (SVT). Surface Blood Clots. — Early Treatment of Serious SVT is With Blood Thinners.

Anti-inflammatories for surface blood clots

SVT causes painful inflammation within the affected vein, and as such, patients may get significant benefit from regular use of anti-inflammatories, such as Ibuprofen (Neurofen). Some patients cannot take anti-inflammatories because they can affect kidney function or interfere with other medications. A patient’s GP will advise on alternative medications.

Topical anti-inflammatory creams or Hirudoid cream, can also provide some symptom relief.

Compression stockings

Following an SVT, compression stockings are important to support the affected leg and reduce the risk of further blood clots. Medical-grade stockings, fitted by someone trained in correct sizing, are best. Over-the-counter or sports compression stockings may not have adequate compression, as they are often designed for sport.

A follow-up ultrasound scan is usually done after the blood thinners stop and as a result of this update, the status of the blood clot and remaining veins becomes clear, allowing for planning of definitive varicose veins treatment.

Varicose veins treatment

Following a surface blood clot, any remaining varicose veins need treatment to stop recurrent blood clots. Standard minimally invasive treatments for varicose veins result in minimal discomfort and down time following treatment.