Wellness: Blood Clots

These silent demons require early treatment.
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Abby Inkster talks about blood clots
Abby Inkster. Photo by Wes Davis.

Abby Inkster admits it may seem ironic that she, a nurse practitioner, didn’t recognize her own blood clot. But here’s the thing: Clots can be chameleonlike, not what they seem.

Inkster’s came on after back-to-back weekends of wall-to-wall activity—first a 10K run, then a whirlwind trip to Chicago. Her only symptom was left calf pain, so she chalked it up to muscle strain. She was young (33 at the time), super-fit, a never-smoker. A blood clot? Nah.

But when the pain worsened, Inkster saw her doctor, who ordered the telltale ultrasound: It was a clot, all right, medically known as a DVT, or deep vein thrombosis.

It was a surprise, to say the least. But 13 years later, Inkster is one of the lucky ones: She’s still here.

Deep vein clots including DVTs (which usually occur in the leg) and PEs (pulmonary embolisms, which lodge in the lungs) fall under the heading of venous thromboembolism, or VTE. A common plight, VTE affects as many as 900,000 people (1 to 2 per 1,000) each year in the United States, according to the CDC. It can be deadly: An estimated 10 to 30 percent die within a month of diagnosis. About 25 percent of PEs result in sudden death. Early treatment saves lives. But the first step is recognizing that you have a clot.

SYMPTOMS: A SLIPPERY SLOPE—Classic signs of a DVT—most commonly found in the lower leg, thigh or pelvis—include swelling, non-injury-related pain or tenderness, redness and skin that feels warm to the touch. But as Inkster’s story illustrates, not all these boxes need to be checked to spell trouble. “My only symptom was an intense, sharp pain in my calf every time I’d flex the muscle, every time I walked,” recalls Inkster, who lived in Roseville at the time. (She’s since relocated to East Sac.) “I didn’t have any redness, and there was no swelling until maybe 24 hours later, and it was only just a little. It was nothing in the wheelhouse of a DVT.” Even her doctor colleagues at UC Davis (where she still works) concurred, until one shared that his wife had had a DVT and suggested she might be experiencing the same. “I was like, ‘huh?’” says Inkster. If medical professionals can miss the signs, anyone can, and sometimes there are no signs to miss: According to the CDC, about half of all DVTs are asymptomatic.

Of grave concern is that these silent DVTs can quietly turn into life-threatening PEs. “We may not have any symptoms [of a DVT] until it breaks off and goes to the lung,” says Richard White, M.D., chief of general medicine at UC Davis Health and a thrombosis expert. Common PE signs include shortness of breath, chest pain that worsens with deep breathing, coughing with or without blood, and a fast or irregular heartbeat. But like DVTs, PE symptoms can be “dicey, and very subtle,” warns White, who runs a 3,000-patient anticoagulation clinic at UC Davis. “You might just feel you’re not getting enough air, or if you do have chest pain, it can be a very classic, sudden onset. Most people think it’s a heart attack.” Fainting or collapse (syncope) can also signal a PE, White adds.

THE ER IS YOUR FRIEND—For any of these symptoms, the message from experts is the same: Get yourself to the ER—immediately. “The most important thing is early recognition and to be seen,” says vascular surgeon Richard Florio, M.D., F.A.C.S., physician-in-chief at Kaiser Permanente Roseville. “‘Be seen’ means urgently be seen.” Inkster waited three days to see a doctor, and she warns others not to make the same mistake. “In hindsight, waiting three days was pretty risky,” she admits.

Though Inkster went first to her primary physician, the ER is the place to go, echoes White, laying out the reasons. “Your primary doctor may miss what’s going on, and if a DVT is suspected, you’re going to need an ultrasound,” he says. A simple blood test, known as the D-dimer test, can help rule out a blood clot and is another useful diagnostic tool, White notes. According to the American Society of Hematology, D-dimer, a protein fragment, is produced when a blood clot dissolves. A positive D-dimer test (meaning higher levels than normal) indicates a clot may be present, signaling a need for additional diagnostics.

TREATMENT IS TRICKY—BUT IT WORKS—When Inkster’s DVT was diagnosed, she was immediately whisked to the anticoagulation clinic and started on meds the same day. “That’s standard protocol,” she says. “Patients don’t leave that clinic until they’ve started on medication.” Popularly known as blood thinners, anticoagulants prevent new clots from forming and stifle growth of existing ones. They often save lives. But they’re also tricky business, even for medical professionals like Inkster, who ended up on both enoxaparin (Lovenox) and warfarin (Coumadin). While self-injecting the Lovenox was not a challenge, Coumadin is by nature more of a teeter-totter, Inkster says, requiring constant monitoring and, typically, frequent dosage adjustments. It took six months, but the meds—plus compression socks, which Inkster says she wore “pretty religiously”—were successful in preventing a post-thrombotic event. (Recurrences and long-term complications are common.) “I haven’t had any lasting effects from my DVT,” says Inkster. “I was very lucky in that way.”

That was in 2009, and Lovenox and Coumadin are still mainstays in blood clot treatment. But science is never static, and options continue to emerge. Some of the newer meds, all direct oral anticoagulants, include rivaroxaban (Xarelto), apixaban (Eliquis) and dabigatran (Pradaxa). But while the names change, the question for most patients remains the same: How long? While a short course may be sufficient for some, being on blood thinners long term or even for life is “not uncommon,” says Anjlee Mahajan, M.D., assistant clinical professor and hematologist at UC Davis Health and a thrombosis researcher. Typically, she says, lifelong meds are recommended for patients who have had what’s known as an “unprovoked” blood clot—one that cannot be attributed to a likely cause. For these individuals, she says, the likelihood of recurrence is high, outweighing the bleeding risks associated with anticoagulant use.

HOSPITALIZATION AND SURGERY AMONG TOP RISKS—It’s unsettling but true: About half of all blood clots happen during or within three months after a hospitalization or surgery, according to the National Blood Clot Alliance and the CDC, which joined forces for a public health campaign, Stop the Clot, Spread the Word (stoptheclot.org). Blood clots are also cited as a leading cause of preventable hospital death in the United States. So what are hospitals doing about it? According to Dignity Health’s Amardeep Singh, M.D., a cardiologist and chairman of cardiology at Mercy San Juan Medical Center, it’s now standard practice for most hospital patients to receive a preventive dose of blood thinners. UC Davis’s White says the same.

“Hospitals routinely do this for patients who are going to be immobile, or who are having any kind of surgery,” Singh says. Prolonged bed rest, extended time in a wheelchair or just sitting for long periods of time all raise the risk of clots. In addition to blood thinners, hospitals also combat clot risks with tools such as leg compressors, which help to improve circulation, notes Singh.

Patients can be proactive, too. If you’re going in for surgery, it’s a good idea to talk to your doctor about your blood clot risks and inquire about preventive measures.

OTHER RISK FACTORS (AND THE TRUTH ABOUT TRAVEL)—There’s a laundry list of other risk factors for blood clots, including aging, being overweight, smoking, using estrogen, physical trauma, cancer and family history. Pregnancy also increases the likelihood of clotting, pointing to the role those devil hormones can play. In Inkster’s case, the hormonal connection has been a double whammy: Her NuvaRing birth control device may have been part of the perfect storm that caused her DVT 13 years ago; more recently, when fertility treatments and an IVF pregnancy required nonstop hormone treatments, Lovenox was prescribed as a precautionary measure. “Anyone on hormone therapy needs to realize this can be a risk factor,” Inkster cautions. But as experts remind us, even those without obvious risk factors can brew a clot. “Anyone is potentially at risk,” says Kaiser’s Florio.

On the bright side, there’s this: Air travel, long ballyhooed as a major harbinger of DVTs, may not be as dangerous as we’ve been led to believe. “The idea that air travel, or any kind of travel, is a significant risk factor for blood clots is just not true,” says White, adding that “99.9% of people who travel never get a blood clot.” The bigger concerns, he says, are individual risk factors and physiology. “Maybe if it’s an older person with underlying conditions who never gets up for 13 hours—maybe that’s a scenario.” Still, he says, it’s important to get up and stretch routinely, especially on long flights, to counteract the immobility issue.

THE COVID CONNECTION—Public interest in blood clots may currently be at an all-time high for a novel reason: COVID-19. The COVID/clot connection first reared its head with the Johnson & Johnson vaccine debacle of 2020, in which the vax was temporarily yanked off the market after six U.S. women developed clots. (The FDA and CDC subsequently deemed it safe and recommended its use.) The Oxford-Astra-Zeneca COVID vaccine has also been linked to clots.

But it’s the virus itself—not the vaccine—that poses the greatest threat of blood clots, says Dignity’s Singh, and the data back her up: According to the National Blood Clot Alliance, a review of several studies suggests COVID-19 patients have an overall blood-clotting incidence rate of about 14%; the number bumps up to an estimated 22% for the more serious cases in the ICU. Hospitalized COVID patients, especially those who require a ventilator or oxygen or who have severe pneumonia, are considered at greatest risk. “Being in the hospital, being immobilized, being sick—all of these factors are at play,” says Singh.

While a pandemic is one heck of a way to inspire interest in blood clots (they were around long before COVID arrived, after all), it’s raised awareness, and that’s a good thing, Singh says. “With or without COVID, DVT has had a high degree of mortality in our community, especially when it’s not recognized and treated and becomes something more severe, like a PE,” she says.

Educating the public, she says, is a big part of the solution.