DVT can become dangerous if the blood clot breaks off and travels through the bloodstream to the lungs. This causes a blockage called a pulmonary embolism (PE) and can be life-threatening.
The Connection Between DVT and PE
Think of pulmonary embolism as a complication of deep vein thrombosis, explains Roy Silverstein, MD, a professor and chair in the Medical College of Wisconsin’s division of hematology and oncology in Milwaukee. Important things to know about DVT and PE:
You can have DVT and not know it, especially if the clot is small.The most common symptoms of DVT are swelling in an arm or leg, tenderness that isn’t from an injury, and skin that feels warm and is red in the area of the clot.A clot usually forms in just one leg or arm, not both.You’re at a greater risk for a PE if you have deep vein thrombosis or a history of DVT.
Like DVT, you can have a PE and not know it. “With a PE, one of three things happens,” says Andrea Obi, MD, a vascular surgeon at Michigan Medicine in Ann Arbor. “Sometimes it will plug up just a very small blood vessel in the lung, and the remainder of the lung will compensate and the person may not even know it happened.” A second scenario, she says, is that “the clot will break off and travel to the lung and block a slightly larger blood vessel that impairs the ability of the lung to exchange blood that’s returning for blood that’s oxygenated.” This will cause oxygen saturation levels to drop. Signs of PE might include the following:
Shortness of breathA rapid heartbeatChest pain or discomfort that gets worse when you breathe deeply or coughCoughing up bloodFeeling lightheaded or faintFeeling anxious or sweatingFeverHaving clammy or discolored skin
“The third scenario is sudden death, and that’s really what we’re trying to prevent when we talk about making a timely diagnosis of DVT and getting patients on blood thinners right away,” Dr. Obi says.
Diagnosing DVT and PE
DVT and PE aren’t always detected for what they are. “The symptoms are quite subtle, and sometimes it’s a nagging pain in the leg that people don’t pay much attention to,” Dr. Silverstein says. “You think you pulled a muscle — you don’t think it could be a clot.” However, because PE can lead to sudden death, it’s critical to seek medical treatment right away if you think you might be experiencing any of the telltale symptoms. According to the Centers for Disease Control and Prevention, as many as 900,000 people in the United States develop DVT, PE, or both every year. An estimated 60,000 to 100,000 of them die, and most are sudden deaths because the fatal PE goes unrecognized. That need not be the case, however. “As long as we make a prompt diagnosis and treat it, patients do extremely well,” Silverstein says. Most often, DVT can be diagnosed with duplex ultrasound. A sonographer uses an ultrasound machine, sending sound waves through the leg, to observe blood flow in your veins. To diagnose PE, doctors may order a CT scan or a specialized X-ray of your lungs, called a ventilation/perfusion scan; it can also show how much blood is getting to your lungs. During the ventilation part of the scan, you inhale a small amount of a radioactive gas. Radioisotopes are injected into your bloodstream to allow doctors to see where blood flows to your lungs. A blood test known as D-dimer measures a substance found in your blood when a clot dissolves. High levels may suggest blood clots. If your level is normal and you have few risk factors for PE, it could indicate that you don’t have PE.
Managing DVT and PE Blood Clot Disorders
Sitting while traveling long distances in a plane or car can increase your risk for DVT and PE, and “the longer the flight, the higher the risk,” Silverstein says. Women who take hormones, whether birth control pills or estrogen therapy, are also at an increased risk, as are pregnant women and women in the six weeks after childbirth. People who have to spend an extended amount of time in bed, most often because of hospitalization and recovery from an illness or surgery, have a heightened risk, too. Treatment involves medications that thin your blood and slow its ability to clot. Blood thinners won’t break up clots, Silverstein says, but they will stop the clot from growing and prevent further clots. “The body has a natural way of healing itself, and eventually the clot disappears on its own,” he says. If a pulmonary embolism is life-threatening, your doctor can administer a thrombolytic, an agent that will dissolve the clot quickly. Because thrombolytics can cause you to bleed, they’re used only when your life is in danger. “Thrombolytic therapy has to be done in a hospital setting,” notes Silverstein. Sometimes, though not often, surgery is required to remove the blood clot. “If the blockage is big enough where it’s causing really severe deficits in oxygen or strain on the heart, then in those patients we do try to treat them by removing the blood clot," Obi says. Silverstein adds that the most worrisome complication of PE is death. If you have repeated clots, over time they can damage your lungs, and that can lead to chronic heart disease. Most of the time, that doesn’t happen, he says. Once you’ve had a PE, you are at a greater risk of having more. Other factors that could further increase your risk:
Being sedentary or bedriddenBeing overweightUndergoing surgery or breaking a boneHaving stroke, chronic heart disease, high blood pressure, or paralysisHaving severe symptoms of COVID-19Smoking
Age is also a risk factor. “The older you are, the higher your risk,” Silverstein says, “particularly after age 55.” Never ignore DVT or PE symptoms, thinking they will go away, especially if you have risk factors. Because the signs — if any — will be subtle, err on the side of caution.
