Synopsis
Diagnose lower-limb superficial vein thrombosis, exclude associated deep thrombosis, and choose anticoagulation from thrombus length, junction distance and patient risk.
- Suspected lower-limb superficial vein thrombosis needs whole-leg duplex to measure extent and junction distance and to exclude asymptomatic, non-contiguous or contralateral DVT.
- ESVS places SVT less than 3 cm from a deep venous junction in the therapeutic anticoagulation branch; exactly 3 cm is a specialist product-scope boundary, not an automatic fondaparinux prescription.
- For isolated SVT at least 5 cm long and at least 3 cm from a deep junction, ESVS recommends fondaparinux 2.5 mg subcutaneously once daily for 45 days; the UK Arixtra licence is stricter and requires more than 3 cm from the saphenofemoral junction.
Key red flags
Breathlessness, pleuritic chest pain, haemoptysis, syncope, hypoxia or hypotension requires urgent assessment for pulmonary embolism.
Whole-leg swelling, deep venous tenderness or marked unilateral oedema suggests associated DVT, but absence of these signs cannot safely exclude an asymptomatic DVT.
Thrombus less than 3 cm from the saphenofemoral or saphenopopliteal junction enters the ESVS therapeutic branch; an exact 3 cm distance needs specialist selection because ESVS and the UK Arixtra licence meet at different boundaries.
Fever, rapidly spreading erythema, purulence, hypotension, severe pain or tissue crepitus suggests infection or necrotising disease rather than sterile superficial venous inflammation.
Active bleeding, severe renal impairment, very low body weight, pregnancy, thrombocytopenia or interacting antithrombotic treatment requires individual anticoagulant review before prescribing.
Investigation priorities
Confirm superficial thrombus, measure its full length and distance from deep junctions, and inspect deep veins for synchronous thrombosis.
Management branches
Use after a painful superficial cord is suspected and before choosing any anticoagulant intensity or duration.
- Arrange bilateral whole-leg duplex to exclude DVT and record SVT vein, length and exact distance from the nearest deep venous junction.
- If DVT or PE is present, use the relevant VTE pathway; if SVT lies less than 3 cm from a deep junction, arrange therapeutic anticoagulation assessment.