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Small saphenous vein

The small saphenous vein is a superficial vein of the lower limb that plays an important role in venous drainage of the lateral and posterior leg. It originates from the dorsal venous arch of the foot, ascends along the posterior calf, and usually drains into the popliteal vein at the saphenopopliteal junction. Variations are common, and the vein may also communicate with the great saphenous vein or deep venous system.

It is clinically significant in venous insufficiency, varicose veins, thrombophlebitis, and serves as an access point for bypass grafts.

Synonyms

  • Lesser saphenous vein

  • Short saphenous vein

  • External saphenous vein (historical)

Origin, Course, and Termination

  • Origin:

    • Begins at the lateral side of the dorsal venous arch of the foot, arising from the dorsal vein of the little toe

  • Course:

    • Passes posterior to the lateral malleolus

    • Ascends along the posterior aspect of the leg, usually accompanied by the sural nerve

    • Runs between the heads of the gastrocnemius muscle

  • Termination:

    • Typically drains into the popliteal vein at the saphenopopliteal junction in the popliteal fossa

    • May also connect with the great saphenous vein or continue as the Giacomini vein into the posterior thigh

Tributaries and Branches

  • Communicates with the great saphenous vein via intersaphenous veins

  • Receives tributaries from the heel and posterior calf

  • Giacomini vein: continuation of the SSV into the thigh, draining into the GSV or deep venous system

  • Multiple cutaneous tributaries along its course

Relations

  • Anteriorly: Gastrocnemius and soleus muscles

  • Posteriorly: Superficial fascia and skin of posterior leg

  • Medially: Great saphenous vein via communicating veins

  • Laterally: Accompanies sural nerve along most of its course

  • Superiorly: Terminates in popliteal vein within the popliteal fossa

Function

  • Drains venous blood from the lateral side of the foot and posterior calf

  • Provides superficial-to-deep venous communication via the saphenopopliteal junction

  • Plays a role in thermoregulation and venous return during standing and walking

Clinical Significance

  • Common site of varicose veins and venous insufficiency

  • May be involved in superficial thrombophlebitis or propagate thrombus into the popliteal vein

  • Target for endovenous ablation procedures in varicose vein treatment

  • Important in surgical planning for venous bypass graft harvesting

  • Anatomical variations in termination are crucial for interventional and surgical approaches

MRI Appearance

  • T1-weighted images:

    • Normal GSV: intermediate signal lumen with well-defined wall

    • Flowing blood: low signal, but slow flow may appear bright (flow-related enhancement)

    • Fat surrounding vein: bright, aiding identification

    • Thrombus: intermediate-to-high signal, depending on stage of organization

  • T2-weighted images:

    • Normal vein: intermediate-to-low signal

    • Slow flow or stasis: appears bright due to reduced flow void

    • Thrombus: hyperintense in acute phase, hypointense when chronic

    • Excellent for detecting perivenous inflammation or varicosity

  • STIR:

    • Normal GSV: low to intermediate signal

    • Slow flow or thrombosis: bright hyperintense signal

    • Highlights edema, cellulitis, or inflammation in thrombophlebitis

  • Proton Density Fat-Saturated (PD FS):

    • Normal vein: dark circular lumen

    • Slow flow or thrombus: hyperintense signal within lumen

    • Wall thickening and perivenous edema: bright and well-demarcated

  • T1 Fat-Sat Post-Contrast:

    • Normal vein: homogeneous enhancement of lumen

    • Thrombus: appears as non-enhancing filling defect

    • Venous wall enhancement: indicates inflammation, thrombophlebitis, or recanalization

    • Slow flow: gradual delayed enhancement in dependent segments

MR Venography (MRV) – Contrast Enhanced

  • Technique: Gadolinium-enhanced 3D MRV or time-resolved MRV

  • Normal appearance: Continuous, smooth tubular structure extending from ankle to groin

  • Valves: May appear as tiny filling indentations within the lumen

  • Thrombosis: Filling defect or non-enhancing region within lumen

  • Reflux: Demonstrated as retrograde enhancement in dependent segments

  • Slow flow: Bright on early T1-weighted post-contrast images due to pooling of contrast

  • Excellent for evaluating varicosities, reflux patterns, and saphenofemoral junction competency

CT Appearance (CTV)

Non-Contrast CT:

  • Vein may not be clearly visualized, but acute thrombus may appear as a hyperdense filling defect

  • Chronic thrombus appears iso- to hypodense relative to muscle

Post-Contrast CT Venography:

  • Normal vein enhances homogeneously with contrast

  • Thrombosis appears as a filling defect within enhancing lumen

  • Varicose veins visualized as dilated tortuous enhancing veins

  • Surrounding fat stranding suggests phlebitis or inflammation

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Small saphenous vein ct sagittal

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