Synopsis
Distinguish low-risk superficial vein thrombosis from disease near the deep system, exclude concomitant DVT and use evidence-based anticoagulation when extension risk is material.
- Superficial vein thrombosis (SVT) produces a tender, erythematous, palpable cord along a superficial vein; it is not always benign.
- Duplex ultrasound should define thrombus length, distance from the saphenofemoral/saphenopopliteal junction and any concomitant DVT when disease is extensive, proximal or clinically uncertain.
- SVT at least 5 cm long and at least 3 cm from a deep-vein junction is treated with fondaparinux 2.5 mg subcutaneously once daily for 45 days when suitable.
Key red flags
Cord or inflammation approaching the groin or popliteal fossa, rapid proximal spread or extensive length raises deep-system extension risk.
Investigation priorities
Confirm SVT length and location, measure distance to deep junctions and exclude DVT.
Management branches
SVT <5 cm long, >3 cm from a deep junction, no DVT and no major extension-risk feature.
- First: encourage mobilisation as tolerated, limb elevation when resting and warm/cool compresses according to comfort.
- Next: offer topical/oral NSAID or paracetamol if safe; avoid antibiotics without infection.
Key medicines
Fondaparinux2.5 mg subcutaneously once daily for 45 days (licensed course is a minimum of 30 and maximum of 45 days in the eligible high-risk population).
Ibuprofen400 mg orally three times daily with/after food for up to 5–7 days when needed.