Varicose veins are a common condition where veins, most often in the legs, become swollen and twisted. While often associated with both legs, they can also develop in only one. This unilateral occurrence has several specific underlying reasons.
How Varicose Veins Form
Veins return deoxygenated blood from the body back to the heart. To facilitate this upward flow, veins contain tiny one-way valves that open to allow blood through and then close to prevent it from flowing backward. When vein walls weaken or valves become damaged and fail to close properly, blood can pool. This pooling, known as venous insufficiency, causes veins to enlarge, stretch, and become visibly bulging varicose veins.
Why Only One Leg is Affected
Varicose veins can appear in just one leg due to localized factors. An old injury or trauma to a single leg can damage vein walls or valves, disrupting normal blood flow. Also, subtle anatomical differences or variations in vein structure can predispose one leg to more pressure or stress, causing varicose veins to manifest primarily on that side.
A history of deep vein thrombosis (DVT) in one leg is a common cause of unilateral varicose veins. A DVT occurs when a blood clot forms in a deep vein, typically in the leg. This clot can damage the vein and its valves, leading to post-thrombotic syndrome. This syndrome results in chronic venous insufficiency, where blood struggles to return to the heart from the affected leg, causing swelling and often leading to varicose veins in that limb.
Asymmetrical lifestyle or occupational factors can also contribute to varicose veins in a single leg. Activities that consistently place more pressure or strain on one leg, such as specific work postures or repetitive movements, might overload the venous system on that side. This sustained, uneven pressure can weaken vein structures and valves in the more heavily used leg.
Less common causes include May-Thurner Syndrome. This occurs when the right iliac artery compresses the left iliac vein in the pelvic region, restricting blood flow from the left leg back to the heart. This compression increases pressure in the veins of the left leg, often resulting in swelling and varicose veins predominantly on that side.
When to Consult a Healthcare Professional
While varicose veins are often not serious, certain signs warrant medical evaluation. Consult a healthcare professional if you experience:
Sudden onset or rapid worsening of symptoms.
Persistent pain, swelling, tenderness, or warmth in the affected leg, as these can indicate complications.
Skin changes, such as discoloration, thickening, or ulcers near the varicose veins.
Bleeding from a varicose vein.
Any suspicion of a blood clot, indicated by symptoms like throbbing pain, swelling, or warmth in one leg, requires immediate medical attention.