A few weeks ago, a patient came to see me after a long flight from overseas. One of her calves felt sore and looked puffy by the time she landed. At first, she figured she had just been sitting too long. However, her husband insisted she get it checked, and it turned out to be deep vein thrombosis, or DVT. I share her story because it is so common. The signs of DVT are easy to brush off as a cramp, a strain, or tired legs. In this article, I explain what to look for and which symptoms can wait for an office visit. I also explain which ones mean you should call 911 right away.
Key Takeaways
- Swelling in one leg, not both, is one of the most common signs of DVT.
- Calf pain, warmth, redness, and newly visible surface veins in the same leg are important clues.
- Sudden chest pain, shortness of breath, a racing heart, or coughing up blood can mean a pulmonary embolism. Call 911.
- Infection or vein disease can also cause a red, swollen leg. So an ultrasound is the best way to know.
- A quick duplex ultrasound can confirm or rule out a clot without needles or radiation.
What Is DVT?
DVT is a blood clot that forms in one of the deep veins, most often in the calf or thigh. The clot can slow or block blood on its way back to the heart. As a result, blood backs up in the leg and the tissue becomes inflamed.
Some people feel a lot of pain and swelling. Meanwhile, others notice almost nothing. That is what makes DVT so tricky. Even so, the bigger danger is that part of the clot can break loose and travel to the lungs. This is called a pulmonary embolism (PE), and it is a medical emergency. You can read more about venous thromboembolism from the National Heart, Lung, and Blood Institute.
The 7 Signs of DVT to Watch For
The first five signs below are reasons to call your doctor the same day. In contrast, the last two are reasons to call 911.
1. Swelling in one leg. DVT almost always affects a single leg. When a clot blocks a deep vein, fluid leaks into the nearby tissue. So the calf, ankle, or whole lower leg looks puffier than the other side. Swelling in both legs usually has a different cause. Still, new leg swelling on one side deserves a prompt check.
2. Calf pain or tenderness. The pain often feels like a cramp, a pulled muscle, or a deep ache. It may get worse when you stand or walk. Also, some people describe heaviness rather than sharp pain. Because the pain can be mild, many patients wait too long.
3. One leg feels warmer than the other. Inflammation around a clot creates heat. So try running a hand down each leg. A clear temperature difference, especially along with swelling, is an important clue.
4. Red, bluish, or discolored skin. First, the skin over the clot may look flushed or red. In more serious cases, it can take on a bluish or purple tint. For this reason, even faint redness counts if it shows up in one leg for no clear reason.
5. Newly visible surface veins. When a deep vein is blocked, blood looks for a detour through the veins near the skin. As a result, those veins can swell and become easier to see. The key word here is new. Veins you have had for years are a different story.
Emergency Signs of DVT: When to Call 911
The next two signs are different. They suggest the clot may have moved to the lungs.
6. Racing heart or shortness of breath. Call 911. These can be signs of a pulmonary embolism. Chest pain, sudden trouble breathing, or a fast or irregular heartbeat need emergency care right away. Do not drive yourself to the ER, and do not wait to see if it passes.
7. Unexplained cough or coughing up blood. Call 911. A sudden dry cough with no cold to explain it can also signal a clot in the lungs. In more serious cases, a person may cough up blood. Feeling faint or dizzy is another warning sign. Again, call 911 immediately.
Other Causes of a Swollen, Red Leg
Not every red, swollen leg is a blood clot. In my practice, I also see these conditions cause similar symptoms.
- Skin infection (cellulitis), which often causes spreading redness, warmth, and sometimes fever
- Varicose veins, which can cause aching, swelling, and inflamed skin around bulging veins
- Chronic venous insufficiency, where weak vein valves let blood pool in the lower legs
- Lymphedema, a buildup of lymph fluid when the lymph system cannot drain the leg well
- Muscle strain or injury, which usually follows a clear event such as a fall or workout
Overall, several of these look alike from the outside. That is why I do not like patients to guess. An ultrasound gives us a clear answer.
Who Is Most at Risk?
DVT can happen to anyone. However, certain situations raise the odds.
- Sitting still for a long time, such as on long flights, long car rides, or bed rest
- Recent surgery, especially on the hips, knees, or legs
- A personal or family history of blood clots
- Cancer and some cancer treatments
- Birth control pills or hormone therapy that contain estrogen
- Pregnancy and the weeks after delivery
To learn more, see my article on the causes and risk factors of DVT.
How I Check for a Blood Clot
If you have one or more signs of DVT, the next step is simple. First, I ask about your symptoms and recent travel, surgery, or illness. Then I examine your leg. Finally, we perform a duplex ultrasound. Because this test uses sound waves, it is painless. It also uses no radiation.
If we find a clot, treatment usually starts with blood-thinning medicine. This keeps the clot from growing while your body slowly breaks it down. I also explain what living with DVT looks like day to day, so you know what to expect. For more on clots and their treatment, see our venous thrombosis page.
Trust Your Instincts
Now, here is what I tell my patients. If one leg looks different, feels different, or hurts more than usual, trust that feeling and call. After all, early care makes a real difference with DVT.
Coastal Vascular Center is a small, physician-owned practice, not a corporate chain. You will see me at every visit, and I personally perform every procedure. There is no hand-off to a physician assistant or nurse practitioner. For leg symptoms, call us. For chest pain or trouble breathing, call 911 first. Then follow up with us so we can build a care plan together.
Get Your Leg Symptoms Checked With Dr. Ayar
New swelling, pain, or warmth in one leg? We can evaluate your symptoms and use ultrasound to check for a clot. You will see Dr. Ayar at every visit in Pearland or Lake Jackson. If you have chest pain or shortness of breath, call 911 now.
