Our veins have a quiet job—they return blood from your legs back to your heart against gravity. It’s harder work than it sounds, and it all depends on a system of tiny one-way valves that most of us never think about. But what happens when those valves stop working properly? The answer isn’t just about visible veins on your legs; it can be more serious than you’d expect.
 
  • The Valve System: How It’s Supposed to Work
 
Inside every vein in your legs are valves—imagine them as tiny doors that only open in one direction. When your calf muscles contract (especially during walking or exercise), they squeeze the veins and push blood upward toward your heart. The valves open to let blood through, then snap shut to prevent it from flowing back down. It’s an elegant system, and when it works, you don’t notice it at all.
 
But these valves are delicate structures. They can become damaged, stretched, or simply stop sealing properly. When that happens, blood starts to pool in your legs instead of moving efficiently upward. This is called **venous valve incompetence**, and it’s more common than you might think—especially as we age.
  • What Causes Valve Incompetence?
Venous valve incompetence can develop for several reasons:
  • Age and wear:** Veins naturally lose elasticity over time, and the valves weaken.
  • Prolonged pressure:
  • Extended periods of standing or sitting put pressure on leg veins. This is why people in certain professions—nurses, teachers, retail workers—are at higher risk.
  • Previous blood clots:** If you’ve had DVT (deep vein thrombosis) before, the clot can damage the valve structure, even after the clot dissolves.
  • Pregnancy:** The weight and hormonal changes during pregnancy can stretch veins and weaken valves. Many women develop vein problems after pregnancy.
  • Genetics:** If your parents had varicose veins or vein problems, you’re more likely to develop them too
  • Injury or trauma:
  • Damage to the leg can affect vein structure.
  • Obesity: Extra weight increases pressure on leg veins.
The frustrating part? Often, there’s no single cause—it’s simply the luck of the draw, combined with how we live our lives.
 
  • The Two Paths: Varicose Veins vs. DVT
Here’s where it gets important. When valve incompetence develops, your legs face a choice between two different problems. Understanding both helps you know when to be concerned.
 
  • Path One: Varicose Veins
The most common outcome of valve incompetence is varicose veins — those enlarged, twisted veins visible on the surface of the skin. They’re blue, purple, or flesh-coloured; they bulge; and they’re often uncomfortable.
 
Here’s how they develop: When the valves fail, blood pools in the veins instead of moving upward. The vein walls stretch to accommodate the extra blood, and over time, they become enlarged and distorted. The more blood pools, the more they stretch.
 
  • Symptoms include
  • Visible, enlarged veins
  • Aching, heaviness, or fatigue in the legs
  • Swelling in the lower legs and ankles
  • Itching or burning skin
  • Throbbing pain, especially at the end of the day
  • Restless legs at night
  • Varicose eczema 
 
Varicose veins are often dismissed as a purely cosmetic problem. They’re not. Left untreated, they can progress to **Chronic Venous Insufficiency (CVI)**, where the skin becomes damaged, discoloured, and prone to ulcers that are difficult to heal.
 
**The good news?** Varicose veins are very treatable. Modern procedures—from minimally invasive laser treatment to sclerotherapy—can close damaged veins and redirect blood to healthy ones.
The second, more serious outcome of valve incompetence is **deep vein thrombosis (DVT)—a blood clot in the deep veins of the leg.
 
Here’s the mechanism: When blood pools in a vein due to valve failure, it moves slowly. Slow-moving blood is more likely to clot. A clot can form in the deep veins (not the surface veins where varicose veins appear), and this is dangerous. If the clot breaks free and travels to your lungs, it becomes a pulmonary embolism (PE)—a life-threatening emergency.
 
Risk factors for DVT in people with valve incompetence:
  • Prolonged immobility (long flights, bed rest, or extended sitting.
  • Recent surgery or injury
  • Pregnancy and the postpartum period
  • Hormonal contraceptives or HRT
  • Cancer or recent chemotherapy
  • Smoking
  • Obesity

 

    • Symptoms of DVT
  • Sudden swelling in one leg (not both)
  • Pain, tenderness, or warmth in the calf or thigh
  • Red or discoloured skin
  • Veins that appear more prominent than usual
 
DVT is a medical emergency.
If you experience these symptoms, seek medical attention immediately. Don’t wait, don’t assume it’s just a pulled muscle.
 
Why do some people with valve incompetence develop varicose veins, while others develop DVT?
 
The answer lies in multiple factors working together:
 
  • Blood flow patterns: Some people’s venous systems respond to pooled blood by creating visible surface veins (varicose veins). Others experience more significant stasis (slowness) in the deep veins, increasing clot risk.
  • Inflammation: Some people’s veins respond to damage with more inflammation, which can trigger clotting. 
  • Genetic factors:
    • Your inherited tendency toward clotting, vein elasticity, and valve structure all play a role.
  • Lifestyle factors:
    • Activity level, diet, hydration, and leg movement influence whether blood pools dangerously or simply pools visibly 
  • The Crossover:  Can you have both?
    • Yes. Some people develop varicose veins *and* are at higher risk for DVT. In fact, having varicose veins is itself a risk factor for DVT, because the damaged valve system affects both surface and deep veins.
This is why it’s not smart to ignore varicose veins as “just cosmetic.” They’re a sign your venous system isn’t working properly, and that sign should prompt investigation and, ideally, treatment.
 
 
Before we talk about treatment, let’s talk about compression. If you have valve incompetence—whether you’ve got visible varicose veins or are concerned about DVT risk—compression is one of the most effective, non-invasive tools available.
 
  • Why wear compression socks?
  • Compression socks (or stockings) are designed to make veins drain faster and more efficiently. They work by compressing the calf muscle—your body’s natural pump—which pushes blood back up to the heart. By doing this, compression can help prevent:
  • Pooling of blood in your lower limbs
  • Dull aching, throbbing, or itching at the end of the day
  • Swelling
  • Blood clots forming in your lower limbs (which could travel toward your heart and become life-threatening)
  • Compression socks feel tighter around your ankle and get looser as they go up your leg.** That’s the design—it creates a pressure gradient that genuinely works.
 
  • Why compression on flights and during travel?
In a nutshell, high altitude puts pressure on your body and affects your big limbs, like legs. Symptoms can include swelling of the feet and ankles or developing a blood clot. Compression socks hug your leg pump (your calf muscle), helping to circulate blood more effectively while you sit through your journey. The stimulation of blood flow also helps for prolonged sitting or standing, so even if you’re not travelling by plane, compression will help with your journey through daily life.
 
But here’s the thing: not all compression is created equal. Over-the-counter compression socks are better than nothing, but medical-grade compression socks, fitted properly by a compression fitting specialist, are significantly more effective. At Specialist Vein Health, we offer medical-grade compression garments fitted by a compression garment specialist or vascular nurse. This means your socks are properly sized for your leg, the compression level is appropriate for your condition, and you’re actually getting the benefit you need—not just wearing something that feels tight.
 
  • Getting Properly Diagnosed: The Ultrasound Investigation
Before starting compression or any treatment, you need to understand what’s actually happening in your veins. This is where vascular ultrasound comes in.
 
Many people assume varicose veins are just a surface problem. They’re not. Your visible veins are only part of the story. The real issue is often in the deep veins, and that’s where DVT risk lurks.
 
At Specialist Vein Health, our vascular sonographers perform ultrasound scans – the road map of your entire venous system.
This ultrasound:
  • Identifies which valves are failing
  • Shows whether blood is pooling in deep veins (DVT risk)
  • Determines the severity of your condition
  • Guides exactly which veins need treatment
  • Rules out other potential issues
This diagnostic imaging is essential. You can’t treat what you can’t see, and a proper ultrasound gives us—and you—the complete picture. It’s the difference between guessing and knowing.
 
  • Treatment: When Compression Isn’t Enough
For many people, compression socks, staying active, and lifestyle changes are enough. But if your valve incompetence is progressive, or if you’re experiencing significant symptoms or clotting risk, treatment is available.
 
Radiofrequency Ablation (RFA)
 
Radiofrequency ablation is a minimally invasive procedure that uses heat energy to seal damaged veins from the inside. Here’s how it works:
 
  • Our vascular specialist uses ultrasound guidance to insert a thin catheter (tube) into the damaged vein
  • The catheter delivers radiofrequency energy, which heats and seals the vein wall
  • The vein closes, and blood is automatically redirected to healthy veins
  • The procedure typically takes 30–45 minutes
  • You can usually return to normal activities within a few days
 
Why RFA works:
It addresses the problem at its source—the failing valve. By sealing the problematic vein, we eliminate pooling and reduce your DVT risk.
 
 
Sclerotherapy is another effective option, particularly for smaller varicose veins and spider veins. During sclerotherapy:
 
  • A specially formulated solution is injected directly into the damaged vein
  • The solution irritates the vein wall, causing it to collapse and seal
  • The vein then fades over time as your body reabsorbs it
  • Multiple veins can be treated in one session
  • Results improve over several weeks
 
Why sclerotherapy works:
It’s precise, effective for surface veins, and has minimal downtime. Many people combine sclerotherapy with radiofrequency ablation for comprehensive results.
 
Both treatments are outpatient procedures—you come in, have treatment, and go home the same day. Both have high success rates and low complication rates when performed by experienced vascular specialists.
 
If you have visible varicose veins or symptoms like aching, swelling, or heaviness in your legs:
 
– Don’t assume they’re harmless. Book a consultation with one of our vascular or vein specialists who can assess your venous system and rule out deep vein involvement.
  • Medical-grade compression socks are genuinely helpful and should be your first line of defence while you seek diagnosis and treatment. Let our compression specialist fit you properly.
  • Stay active. Movement helps your calf muscle pump blood upward, reducing pooling.
  • Avoid prolonged sitting or standing.
  • Stay hydrated and maintain a healthy weight.
  • If you’re taking hormonal contraceptives or HRT, discuss your vein health with your doctor.
Understanding your vein health is part of understanding your overall health. Vein problems don’t just affect how your legs look; they affect circulation, comfort, and in the case of DVT, safety.
 
The Bottom Line
 
Venous valve incompetence is common, but it’s not something to ignore. Whether it manifests as varicose veins or puts you at risk for DVT, it’s a sign your venous system needs attention.
 
The good news? Modern vein treatments are effective, minimally invasive, and life-changing. You don’t have to live with painful, swollen legs or worry about hidden clot risk. From compression fitting to ultrasound diagnosis to radiofrequency ablation or sclerotherapy, we have solutions at every stage.
 
 
If you’re concerned about varicose veins, leg swelling, DVT risk, or just want to understand your vein health, book a consultation with one of our vascular or vein specialists.
 
Specialist Vein Health has clinics in 
 
  • Wellington (including Lower Hutt)
  • Auckland (North Shore)
  • Kapiti
  • Palmerston North
  • Nelson
 
Our team includes vascular specialists, vascular sonographers for ultrasound diagnosis, compression specialists, and nurses trained in vein care. Whether you need compression fitting, diagnostic ultrasound, or treatment, we’re here to help.
 
  • Disclaimer: This blog is for educational purposes and should not replace professional 
medical advice. If you experience symptoms of DVT (sudden swelling, pain, warmth, 
or redness in one leg), seek immediate medical attention.