Can Varicose Veins Be Deep and Invisible?
No, by definition varicose veins cannot be "deep" - they are subcutaneous (under the skin) veins that are dilated to at least 3 mm in diameter, but the underlying venous reflux causing them can originate from deep veins that are not visible. 1
Understanding the Terminology
The confusion here stems from mixing two distinct concepts:
Varicose veins themselves are always superficial, subcutaneous structures. They must be at least 3 mm in diameter when measured with the patient upright 1. While they are typically visible as bulging veins, smaller varicose veins may not be readily apparent on casual inspection.
The underlying venous reflux causing varicose veins can originate from deeper incompetent veins (like the great saphenous vein, perforating veins, or deep venous system) that are not visible on the surface 1.
"Hidden Varicose Veins"
The term "hidden varicose veins" refers to superficial venous reflux that exists without visible bulging veins on the surface 2. This is an important clinical entity because:
- Patients can have symptomatic venous insufficiency (aching, heaviness, swelling) without obvious visible varicosities
- The incompetent veins causing symptoms are still in the superficial venous system, just not prominent enough to see
- These still require proper evaluation with duplex ultrasound 1
The Deep Venous System
Deep veins are anatomically separate from varicose veins. The venous system has three components 3:
- Superficial veins (where varicose veins occur)
- Deep veins (femoral, popliteal veins - these don't become "varicose" but can have reflux or obstruction)
- Perforating veins (connecting superficial to deep systems)
Deep venous insufficiency or obstruction can contribute to the development of superficial varicose veins, but the deep veins themselves don't become varicose 1.
Clinical Implications
When evaluating any patient with leg symptoms or visible varicosities, duplex ultrasound is mandatory 1, 3. This imaging will assess:
- The deep venous system for patency and reflux (>500 ms in superficial/deep calf veins, >1000 ms in femoropopliteal veins) 1
- Superficial truncal veins (great and small saphenous veins)
- Perforating vein incompetence (>350 ms reflux) 1
- Location and extent of any reflux pathways
The key pitfall: Don't assume absence of visible varicose veins means absence of venous disease. Patients with leg symptoms (heaviness, aching, swelling) warrant duplex evaluation even without prominent surface veins 1, 2.