For an NFL quarterback, a sore calf might seem like an unsurprising consequence of getting hit by a cleat. In Jalen Hurts’ case, an ultrasound revealed something else: a superficial blood clot.
The Philadelphia Eagles quarterback was struck in the calf during an Oct. 4 game and sought treatment four days later, according to a statement from the team. An ultrasound in London revealed the clot, but doctors cleared him to play in the team’s game there the next day.
Then, a follow-up ultrasound Wednesday night revealed “movement in the small blood clot.” The Eagles announced Thursday that Hurts would miss Sunday’s game against the Carolina Panthers while the team determines his treatment.
What makes a clot superficial—and when does it become dangerous? We asked doctors to explain.
What’s the difference between a superficial clot and deep vein thrombosis?
To understand blood clots, picture a road map. Your deep veins run within the muscles of your arms and legs, carrying most of the blood returning from your limbs to your heart. Superficial veins sit closer to the surface, just underneath the skin and in the tissue beneath it. Connecting veins bridge the two systems.
“You have a really well interconnected network of veins,” says Dr. William Shutze, a vascular surgeon at Texas Vascular Associates in Dallas and vice president of the Society for Vascular Surgery (who was not involved in Hurts’ care). Think of it as “a very well developed road and highway system,” with multiple routes to get where you need to go.
When a clot blocks one route, blood can take a detour through other veins.
A superficial clot forms in one of the veins near the skin. The area can become red, warm, and tender. “It’s usually very uncomfortable,” Shutze says. Some develop in varicose veins; others form where a needle or IV has irritated a vein.
You can sometimes feel the affected vein beneath your fingers. “It’s like a pencil underneath the skin, or a knot,” says Dr. Stephan Moll, a hematologist and professor of medicine at the University of North Carolina who runs an Athletes and Blood Clots Clinic (who was not involved in Hurts’ care).
Deep vein thrombosis involves a clot farther inside the body. Its symptoms can be more widespread—the whole calf or ankle might become swollen and painful, Moll says. You can’t feel the deep vein itself.
Many superficial clots stay put and get better without blood thinners. But sometimes, a clot grows into one of the deeper veins. A piece can then break off and travel to the lungs, causing a potentially life-threatening complication called a pulmonary embolism.
Doctors use ultrasound to assess the clot and check for deep-vein involvement, Shutze says. They’re particularly concerned about superficial clots longer than 5 centimeters or within 3 centimeters of where a superficial vein joins a deep one.
The Eagles haven’t specified those details. And “movement” isn’t precise enough to establish what happened. “That’s not a term we use in clinical practice,” Moll says. It could describe a clot growing or extending; it doesn’t, by itself, establish that a piece broke loose or reached the lungs.
How do these clots happen—and how are they treated?
Being in excellent shape doesn’t make someone immune to a blood clot. An injury can damage a vein, while prolonged inactivity slows blood flow. Surgery, certain inherited clotting disorders, cancer, and pregnancy can also increase risk, says Dr. Alina Mitina, an emergency medicine physician at Hackensack University Medical Center in New Jersey (who was not involved in Hurts’ care).
Veins near the skin have less cushioning when someone takes a hit. “The deeper veins are protected,” Shutze says, although a severe impact can injure those, too.
A clot can form within hours of an injury or develop over several days, he adds. If your leg already hurts from getting hit, you might not realize there’s another reason it’s sore.
Travel can add another risk: Sitting through a long flight or car ride means the legs aren’t moving as much, slowing blood flow.
Some superficial clots can be managed with warm compresses, anti-inflammatory medication, elevation, and monitoring. Others need blood thinners to help keep the clot from growing—even if it hasn’t reached a deep vein.
If blood thinners are needed, treatment is usually temporary, Moll says, often lasting several weeks.
That doesn’t necessarily mean spending recovery on the couch. “We like them to be active because we want to keep the blood flowing,” Shutze says.
Getting up for a walk, of course, is different from getting tackled. Shutze worries about athletes taking another hit where they already have a clot. Blood thinners add another concern: An injury that causes bleeding can become much more dangerous when blood doesn’t clot as readily.
In football, “you have constant significant contact,” Moll says, which raises the risk of serious bleeding, including inside the head or muscles.
What symptoms shouldn’t you ignore?
Athletes are used to being sore. “They often minimize clinical symptoms, completely understandably, because they don’t want to be taken off the roster,” Moll says.
Pay attention when discomfort feels different, persists, or worsens. Pain, swelling, discoloration, and warmth can signal a clot. Mitina says patients sometimes describe tightness in the leg; redness around a superficial clot can resemble an infection.
If you think you might have a superficial clot, “don’t ignore it,” Shutze says. Have a doctor check it out rather than assuming it’s a bruise or muscle strain.
Unexplained shortness of breath, chest pain, coughing up blood, or fainting require emergency care because they can signal a pulmonary embolism. Moll also flags an unexplained cough and fast heart rate as possible warning signs.
And getting checked once doesn’t mean you should brush off symptoms that persist or worsen. “If something feels weird or symptoms aren’t getting better, always return to the ER,” Mitina says. “You know your body best.”