Superficial vein thrombosis (SVT) occurs when blood in a vein directly under the skin clots. SVT causes vein tenderness, pain, and skin discolouration. Over time, the vein hardens into a firm, nontender, easily palpable lump. SVT commonly occurs in the veins of the leg. Each year, 1 per 1000 people over the age of 18 have SVT. SVT is painful but usually gets better within a month. Four in 100 people with SVT develop progressively worse blood clotting involving the deep veins or lungs.

If a deep vein clot in the leg occurs it can cause permanent disability with post-thrombotic syndrome (long-term leg pain and swelling) and reduced quality of life. If a pulmonary embolism occurs it may cause chest pain, breathlessness, pulmonary hypertension, psychological distress, and potentially death. Guidelines tell doctors to use ultrasound scanning to decide whether SVT needs treatment with a blood thinner or not. Blood thinners prevent the clot from worsening.

Many people who have SVT go to the emergency department. Scanning is limited to the daytime so often people have multiple trips to the emergency department for their scan and they spend many hours waiting for a doctor to see them. Our research group developed simple ways to limit the need for scans for other types of blood clots, like blood clots in the lungs or in the deep veins. We use a simple blood test called D-dimer. We believe we may be able to use D-dimer to help limit the need for SVT scanning.

This is an exploratory study to document what happens to patients tested for SVT in the emergency department, and to see if the D-dimer blood test might be useful in reducing scans. Our research group will review the emergency department charts for patients who came to the emergency department with SVT. Our results will tell us whether further studies would be helpful.

Inclusion Criteria:

• Aged ≥ 18
• Tested for superficial vein thrombosis in the emergency department or urgent care centre
• Patients tested for SVT at all sites, including arms, legs and torso

Exclusion Criteria:

• Patient opted out of research at the participating site
• Patient included in the study in the last 90 days

Emergency department patient who is tested for superficial vein thrombosis