If you have venous insufficiency, then you may be at an increased risk of developing deep vein thrombosis (DVT). DVT is a type of vascular disease in which a blood clot, also known as a thrombus, forms in a vein that lies deep within the legs. Since DVT is a potentially life-threatening medical problem, it’s important to see a vein specialist at a clinic in Houston if you display any of the possible signs of DVT.
Quick Answer: Deep vein thrombosis (DVT) is a blood clot in one of the deep veins, usually in the calf or thigh. It typically causes swelling, aching or cramping and warmth in one leg, although some clots cause no symptoms at all. The main danger is a pulmonary embolism, when part of the clot travels to the lungs. DVT is diagnosed with a venous duplex ultrasound and is usually treated with blood thinners. Sudden leg swelling with pain, or any shortness of breath or chest pain, needs same-day medical care.
Meet your vein specialist
Dr. Syed Raza, MD
Vascular & Interventional Radiology · Founder, Premier Vein & Vascular Center
Fellowship-trained interventional radiologist certified by the American Board of Radiology and the Royal College of Radiologists (UK). Former Chief of Interventional Radiology at UTMB Galveston and Memorial Hermann Memorial City, with 15+ years treating varicose veins, venous reflux and peripheral arterial disease.
Causes and Risk Factors
Patients may develop DVT because of any underlying medical problems that inhibit circulation in the legs, such as venous insufficiency. DVT may also be indicative of a blood clotting problem. For instance, some people may inherit blood clotting disorders that make their blood more likely to clot. When you visit a vein specialist, he or she will help you explore some of the risk factors that you may have for DVT. If you’re a woman, these risk factors may include using hormonal birth control or hormone replacement therapy. Obesity, pregnancy, a history of traumatic injury to the area, or a history of recent surgery may also increase your risk. Some people develop DVT after receiving cancer treatment. Certain cancer treatments and sometimes cancer itself may increase the risk of abnormal blood clotting. Other risk factors include advanced age, sedentary lifestyle, tobacco use, heart failure, and inflammatory bowel disease (IBD).
Signs and Symptoms
It is possible for DVT to develop without the patient noticing any symptoms at all. When symptoms do arise, they typically include pain or cramping in the affected leg. It may feel as though the muscle is sore, just like it might be after vigorous exercise. An area of sudden swelling on one or both legs is also a red flag. Some patients may not notice symptoms until DVT has caused complications such as pulmonary embolism. This occurs when the blood clot breaks free and travels in the bloodstream to the lungs. Some of the signs of pulmonary embolism include shortness of breath, dizziness, faintness, chest pain that worsens upon breathing or coughing, bloody cough, and a rapid pulse. These symptoms require emergency medical care.
To learn more about deep vein thrombosis visit our website.
How Deep Vein Thrombosis Forms
Blood is designed to stay liquid while it moves and to clot quickly when a vessel is injured. A DVT happens when that balance tips the wrong way inside a deep vein. Doctors describe three conditions that make this more likely, and most clots involve at least two of them.
- Slow blood flow. When you sit or lie still for hours, the calf muscle pump stops pushing blood upward and it pools in the deep veins. Long flights, car trips, hospital stays and recovery from surgery are common examples.
- Damage to the vein wall. Surgery, fractures, injury and catheters placed in a vein can irritate the inner lining and trigger clotting.
- Blood that clots more easily. Inherited clotting conditions, cancer and its treatment, pregnancy, estrogen-containing medications and dehydration all shift the blood toward clotting.
Clots usually start in the calf veins, often in the pockets behind the valves where flow is slowest. Some stay small and dissolve on their own. Others grow and extend up into the knee, thigh and pelvic veins, where they are larger and more likely to break loose.
Deep Vein Thrombosis vs Other Causes of Leg Pain and Swelling
A sore, swollen calf has many possible causes, and DVT can look very similar to harmless problems. This is why we never diagnose or rule out a clot by examination alone.
| Condition | Typical features | How it is confirmed |
|---|---|---|
| Deep vein thrombosis | Swelling of one calf or whole leg, aching or cramping, warmth, sometimes redness; may follow surgery, travel or illness | Venous duplex ultrasound |
| Superficial thrombophlebitis | Hard, tender, red cord along a visible surface vein, often a varicose vein | Ultrasound to measure its extent and check it is not near the deep veins |
| Muscle strain or tear | Sudden pain during activity, bruising, little swelling of the whole leg | History and examination; ultrasound if unclear |
| Baker’s cyst | Swelling or fullness behind the knee; can rupture and mimic a clot | Ultrasound |
| Cellulitis | Spreading red, hot, tender skin, often with fever | Examination; ultrasound to exclude a clot |
| Chronic venous insufficiency | Both legs, swelling worse at day’s end, varicose veins, slow onset | Ultrasound showing reflux |
Superficial clots deserve attention too. When a clot in a surface vein lies close to where it joins the deep system, it can extend into the deep veins, and some patients need blood thinners for it.
Call 911 or seek emergency care if you have:
- Sudden shortness of breath, especially if it is new or worse when lying flat
- Chest pain that gets worse with a deep breath or cough
- Coughing up blood, a racing heartbeat, fainting or lightheadedness
- Sudden swelling, pain and warmth in one leg, particularly after surgery, travel, injury or childbirth
- A leg that turns blue, very swollen and very painful
How Deep Vein Thrombosis Is Diagnosed
The standard test for DVT is a venous duplex ultrasound. It is painless, uses no radiation and can usually be completed in under an hour. The technologist presses gently on the veins with the ultrasound probe: a healthy vein squashes flat, while a vein containing clot does not. Color Doppler shows whether blood is moving through each segment.
A blood test called a D-dimer is sometimes used in emergency settings. A normal result can help rule out a clot in people at low risk, but a raised result is not specific, because surgery, infection, pregnancy and older age can all raise it. If a pulmonary embolism is suspected, a CT scan of the chest is usually needed, which is done in a hospital setting.
How We Evaluate a Possible DVT at Premier Vein
When a patient comes to us with leg swelling or pain and a clot is a possibility, our evaluation is quick and focused:
- Focused history. We ask when symptoms started, recent surgery, travel, injury or illness, pregnancy or hormone use, cancer history, previous clots and family history of clotting.
- Examination. We compare both legs for swelling, tenderness, warmth and color, look for surface vein clots, and check the pulses in the feet.
- Venous duplex ultrasound. Performed in our IAC-accredited vascular lab, the scan examines the deep veins from the groin to the calf and the superficial veins as well.
- A clear plan. If a clot is found, we explain where it is and how extensive it is, start or coordinate treatment, and arrange follow-up. If chest symptoms suggest a pulmonary embolism, we direct you to emergency care right away.
Deep Vein Thrombosis Treatment
Blood thinners
Most DVTs are treated with anticoagulant medication, often called blood thinners. These medicines do not dissolve the clot directly. They stop it from growing and lower the chance of new clots, while the body gradually breaks down the existing clot over weeks to months. Many patients are treated as outpatients with tablets. The usual course is at least three months, and longer when the cause is ongoing or the clot was unprovoked.
Compression and movement
Once treatment has started, walking is generally encouraged rather than bed rest. Compression stockings can ease swelling and aching in the affected leg. Your doctor will advise whether and when to use them.
Procedures for selected clots
For large clots in the thigh and pelvic veins causing severe symptoms, some patients are considered for catheter-based procedures to remove or break up the clot. These are performed by interventional specialists in a hospital setting and are reserved for carefully selected situations. Most patients do well with medication alone.
Treating vein disease that raises clot risk
Long-standing varicose veins and venous insufficiency are linked with a higher risk of clots, as noted above. After a DVT has been treated, patients with refluxing superficial veins often benefit from having them closed with an office procedure such as endovenous thermal ablation, once the timing is right.
Long-Term Effects: Post-Thrombotic Syndrome
A DVT can leave a lasting mark on the leg even after the clot has cleared. As the clot breaks down, it can scar the deep vein and damage the valves inside it. The result is long-term high pressure in the leg, known as post-thrombotic syndrome. It typically causes:
- Chronic swelling and heaviness in the affected leg
- Aching or cramping that worsens with standing
- New varicose veins
- Brown discoloration and thickening of the skin around the ankle
- In more severe cases, slow-healing venous ulcers
Taking blood thinners as prescribed, staying active and managing any superficial vein reflux all help limit these long-term effects. If symptoms develop months after a clot, an ultrasound can show whether the deep veins have healed and whether other veins can be treated to take pressure off the leg.
How to Lower Your Risk of Deep Vein Thrombosis
Not every clot can be prevented, but many can. Practical steps include:
- On long flights and car trips, walk or stretch every one to two hours and do ankle pumps while seated
- Drink plenty of water and limit alcohol when traveling
- Wear well-fitted compression stockings for long journeys if you have risk factors
- After surgery, get moving as soon as your care team allows and follow any clot-prevention plan
- Discuss hormone therapy and birth control with your doctor if you have had a clot or have a family history
- Stay active, keep a healthy weight and do not smoke
- Have long-standing varicose veins and leg swelling evaluated rather than ignored
Questions to Ask After a Deep Vein Thrombosis Diagnosis
A new DVT diagnosis brings a lot of information at once. Patients often tell us they only thought of their most important questions after they got home. These are the ones we suggest bringing to your follow-up visit:
- Was this clot provoked by something specific, such as surgery or travel, or did it happen without an obvious cause?
- How long will I need to take a blood thinner, and what happens when I stop?
- Which medicines, supplements or activities should I avoid while on treatment?
- Do I need testing for an inherited clotting condition or other underlying cause?
- Should I wear compression stockings, and for how long?
- When should I have a repeat ultrasound?
- Do I have varicose veins or reflux that should be treated later?
- What should I do differently before my next flight, surgery or pregnancy?
Write down the name and dose of your blood thinner and keep it with you. Tell every doctor, dentist and pharmacist you see that you are taking it, and ask before starting any new medication, including over-the-counter pain relievers, which can raise bleeding risk.
When to See a Vein Specialist in Houston About DVT
Any sudden leg swelling and pain should be checked the same day, and chest symptoms need emergency care. For patients who have had a DVT in the past, who have lingering swelling or skin changes after a clot, or who have varicose veins and want to understand their risk, a vein specialist can help. Dr. Syed Raza is a fellowship-trained interventional radiologist, certified by the American Board of Radiology and the Royal College of Radiologists (UK), with more than 15 years of experience treating venous disease. If you are looking for a vein specialist in Houston, same-week appointments are usually available, and most insurance plans, including Medicare, are accepted. Our deep vein thrombosis page has more information.
Talk With a Specialist at Premier Vein
Have questions about your symptoms or treatment options? Dr. Syed Raza and the team at Premier Vein & Vascular Center can evaluate your concerns and explain your options clearly. Same-week appointments are usually available, and most insurance plans are accepted.
Frequently Asked Questions
Can a DVT go away on its own?
Small calf clots sometimes dissolve without treatment, but there is no way to know in advance which clots will grow or travel to the lungs. Every suspected DVT should be confirmed with an ultrasound so a doctor can decide whether treatment is needed.
How long does it take for a DVT to dissolve?
The body usually breaks down a clot gradually over several weeks to months. Blood thinners keep it from growing during this time, and most courses of treatment last at least three months.
Should I walk if I have a blood clot in my leg?
In most cases, yes. Once treatment with blood thinners has started, walking is generally encouraged because it improves blood flow and can ease swelling. Follow the specific advice of your treating doctor.
What does a DVT feel like?
Many people describe a cramp, ache or tightness in the calf that does not go away, often with swelling and warmth in one leg. Some clots cause no symptoms, which is why risk factors and any sudden one-sided swelling should be taken seriously.
Can varicose veins cause a DVT?
Varicose veins are linked with a higher risk of blood clots, including clots in surface veins that can extend into the deep system. Having varicose veins evaluated and treated can reduce this risk.
Can I fly after having a DVT?
Many patients can fly once they are stable on blood thinners, but timing should be discussed with your doctor. On the flight, walk regularly, do ankle exercises, stay hydrated and wear compression stockings if recommended.
Trusted Health Resources
- Venous Thromboembolism, National Heart, Lung, and Blood Institute (NIH)
- About Venous Thromboembolism (Blood Clots), Centers for Disease Control and Prevention