According to the Centers for Disease Control and Prevention (CDC), roughly 1 out of 10 hospital deaths are related to a blood clot that breaks off and travels to the lungs, called a pulmonary embolism (PE). Pulmonary embolism is part of a cluster of conditions that fall under venous thromboembolism (VTE). The clotting disorder also includes deep vein thrombosis (DVT), which is when a blood clot forms in a deep vein, usually in the lower leg, thigh, or pelvis. According to Jorge Antonio Gutierrez, MD, a cardiologist and assistant professor of medicine at Duke University in Durham, North Carolina, “VTE is a highly preventable disease among hospitalized patients.” You can take measures to prevent these conditions, but it may be up to you to understand how they can be avoided. A research study published in January 2019 in the American Journal of Medicine found that over half of adult patients who stayed more than two days in U.S. acute-care hospitals following a surgery or an acute medical illness met American College of Chest Physicians criteria for blood clot prevention measures like blood thinners or compression stockings. However, the CDC estimates that roughly half of hospitalized adults don’t receive proper prevention measures. Understanding the warning signs and how to prevent blood clots after or during a hospital stay is a critical part of your care.

VTE and Pregnancy

Pregnant women are five times more likely to experience a blood clot, compared with women who are not pregnant, according to the CDC, and PE is the leading cause of death in women during pregnancy or just after having a baby. Having a cesarean section, diabetes, or certain heart or lung conditions can put a woman at a higher risk of clotting, the CDC reports. Be sure to keep an eye out for the warning signs for the first three months of your baby’s life, when clot risk is still elevated.

VTE and Cancer Patients

Cancer often requires long hospital stays and multiple surgeries, so it isn’t surprising that hospitalization is associated with an increased risk of VTE in cancer patients. In addition, the cancer itself can increase your risk of clotting. The CDC reports that cancers involving the pancreas, stomach, brain, lungs, uterus, ovaries, and kidneys particularly increase the risk of blood clots. Certain blood cancers, such as lymphoma and myeloma, can also put people at a higher risk of developing blood clots, compared with other types of cancer. According to the American Cancer Society, some experts suggest that the tissue damage that some cancers cause might trigger blood clots to form. Some chemotherapies also increase a person’s risk of developing blood clots. An article published in February 2017 in the journal The Oncologist reported that the risk of VTE may be six times higher in cancer patients than in patients without cancer. The authors noted that thromboprophylaxis — preventing clots with anticoagulants like heparin — is generally recommended for most patients hospitalized with active cancer, although your doctor can determine what course of treatment is best for you. The American Cancer Society recommends staying away from over-the-counter anti-inflammatory drugs such as aspirin, naproxen, or ibuprofen if your doctor prescribes blood thinners to mitigate your risk of clotting. The combination can thin the blood too much and cause bleeding.

VTE and COVID-19

Being hospitalized with COVID-19 can keep you immobile for weeks and significantly raise your risk of VTE. A study of patients in Italy hospitalized with COVID-19, published in July 2020 in the journal Thrombosis Research, found that about 20 percent of these patients developed VTE after being hospitalized. A separate study published in August 2021 in the journal Anaesthesia found that patients who got COVID-19 after surgery were three times more likely to develop VTE than those who didn’t get COVID-19. Even those who caught the virus prior to having surgery were twice as likely to develop VTE as those who hadn’t had COVID-19. About 7 percent of patients who had COVID-19 died without having VTE, while more than 40 percent of those who had VTE died. “People undergoing surgery are already at higher risk of VTE than the general public,” the study’s lead author, Elizabeth Li, PhD, a doctoral research fellow in surgical innovation at University Hospital Birmingham, said in a press release. “Surgical patients have risk factors for VTE, including immobility, surgical wounds and systemic inflammation — and the addition of SARS-CoV-2 infection may further increase this risk.”

Prevention and Risk Factors

There are many strategies to help reduce the risk of VTE while you’re in the hospital, including early mobilization, compression devices, and medication. Avoiding a hospital stay in the first place by getting vaccinated against COVID-19 is also an effective way to prevent hospital-associated VTE. According to Dr. Gutierrez, doctors will assess various factors that increase your risk of VTE if you are staying in the hospital. People age 70 or older, people who have had a prior VTE, and those who have cardiovascular disease, cancer, or kidney disease are at a higher risk of VTE. According to the American Heart Association, prolonged immobility, malignancy, major surgery, trauma, prior VTE, and chronic heart failure also increase a person’s risk of having a blood clot after or during a hospital stay. Being in the intensive care unit, recovering from a cesarean section, and having an indwelling central venous catheter are also increased risk factors. “Blood thinners can be administered at very low doses to reduce the risk of VTE in patients who are able to take blood thinners,” says Gregory Piazza, MD, a cardiovascular medicine specialist at Brigham and Women’s Hospital in Boston. “For patients who can’t be on blood thinners, devices like intermittent pneumatic compression boots may help.” Since being immobile is a significant risk factor for developing hospital-related VTE, “Patients are encouraged to be mobile as soon as possible,” says Gutierrez. If you’re unsure of how mobile you can safely be, ask your healthcare provider to explain the specific types of movements you can perform.

Signs of VTE to Watch Out for During a Hospital Stay

It’s important to talk to the doctor when you are admitted to a hospital to ensure that you are taking all of the necessary steps to reduce your risk of VTE. Alert your care staff immediately if you experience any of the following symptoms. DVT-specific signs include:

Swelling in a leg or armPain or tenderness in a leg or arm, not related to another problemIncreased warmth, cramps, or aching in the area that is swollen or painful, usually the calf or thighRed or discolored skin

PE-specific signs include:

Shortness of breathPain with deep breathingRapid breathingIncreased heart rate

If clots aren’t prevented or treated early, complications from VTE can include post-thrombotic syndrome. This is when poor blood flow, inflammation, and blood vessel damage from deep vein thrombosis cause swelling and discomfort. Post-thrombotic syndrome is a long-lasting condition that can lead to disability. Another VTE-related complication is pulmonary hypertension, which can lead to heart failure. Pulmonary hypertension happens when a pulmonary embolism, or clot, blocks blood flow and raises blood pressure in the vessels leading to your lungs. “Deep vein thromboembolism and pulmonary embolism are preventable complications of surgery and medical illness,” says Dr. Piazza. “It’s important for people to know that there are very effective medications and devices to prevent VTE from happening to patients when they’re hospitalized.”

Questions to Ask if You’re Hospitalized

Whether or not your hospital stay was expected, it’s important to ask questions about how to reduce your risk of VTE. Here are a few to start with, but based on your risk factors, your list might be longer. Additional reporting by Kaitlin Sullivan.