COVID-19 & the Risk of Deep Vein Thrombosis

A soon-to-be-published article in the Journal of Vascular Surgery Venous and Lymphatic Disorders noted an increase in the number of cases of deep vein thrombosis (DVT) in patients hospitalized with COVID-19. This was an anecdotal study from one hospital in Italy, but the findings are significant. DVT and pulmonary embolism (PE) already result in a significant number of hospital deaths, according to the National Blood Clot Alliance.

The authors of the upcoming study hypothesize several reasons for this increased incidence of DVT. First, all hospitalized patients are at increased risk for DVT because they are typically immobile. Second, the COVID-19 infection may result in the release of inflammatory molecules that can injure the lining of veins and thus increase the risk of DVT. Finally, the infection may increase procoagulant factors that heighten the risk of blood clotting. Thus, COVID-19-related complications may induce all three of the major risk factors 

for developing a DVT, known as Virchow’s Triad: venous stasis, endothelial injury, and hypercoagulability.


All Hospitalized Patients are at Risk of DVT

It is important to realize that all hospitalized patients are at increased risk for deep vein thrombosis for several reasons. First and foremost, patients in the hospital typically spend most of their time in bed, immobile. Next, many patients have underlying medical conditions, such as infections, that make them more likely to form blood clots. In addition, many patients have had surgery which put them at increased risk of DVT. Patients who have had orthopedic procedures, abdominal or pelvic surgery, or complex cardiovascular procedures are also at increased risk of DVT.

The Good News for Hospitalized Patients

Because the risk of deep vein thrombosis in hospitalized patients is high and can result in death and long-term disability, physicians are careful to make sure that all hospitalized patients have measures taken for DVT prevention. For example, with electronic medical records, “hard stops” are established where the physician writing orders is forced to address DVT prophylaxis.

Multiple steps are taken in hospitalized patients for PE and DVT prevention. Patients who do not have a contraindication to blood thinners generally receive SQ heparin or Lovenox during their hospitalization to prevent blood clotting. Increasing blood flow in the veins also helps prevent DVT, and this can be accomplished in several ways. Medical compression stockings help veins empty more efficiently and reduce the risk of blood clotting in legs. Early ambulation is also useful to increase blood flow. Perhaps the simplest method to increase blood flow is by elevating your legs above your heart. Multiple studies have shown this to be effective in helping with DVT prevention.*

DVT prevention after Hospital Discharge

The risk of deep vein thrombosis often remains high even after discharge from the hospital for several reasons. First, if you have just had surgery, you may still be less active. In addition, after surgery or any major injury your blood may be hypercoagulable (more likely to clot). These issues are important given that the trend is for early hospital discharge.

Fortunately, after being discharged from the hospital, there are steps that you can take for DVT prevention.

  1. Gradually increase your normal activity. Walking specifically increases venous blood flow by activating the calf muscle pump.
  2. Elevate your legs. Leg elevation allows you to take advantage of gravity to increase blood flow in your veins, which helps prevent and dissolve blood clots in legs. It also reduces leg swelling, which is common after many procedures. However, leg elevation is only effective if done correctly.
  3. Wear compression stockings. Medical compression socks and hosiery help prevent pooling of blood in
  4. your veins (venous stasis) and are especially important to wear when you will be standing or sitting for a prolonged time.
  5. Stay hydrated. Dehydration increases your risk of blood clots so drink plenty of water and stay hydrated.


A deep vein thrombosis can result in debilitating long-term consequences. Hospitalized patients are especially at risk. However, you can work on DVT prevention by being mindful of your venous health. Elevate your legs daily to reduce the risk of blood clotting in legs. Choose the right medical compression stockings to wear. Exercise regularly and avoid prolonged sitting and standing. These are things that should be part of your daily routine to help lower the risk of developing DVT or other vein problems.

Author; Dr. Chris Dickson, Board Certified Vascular Surgeon & Inventor of the Lounge Doctor Leg Rest.

  •  Ashby, EC. “Leg Elevation in Prophylaxis of Thromboembolism.” The Lancet, vol. 342, no. 8886-8887, 1993, pp. 1562–1563.,
  •  Sholz PM, Jones RH, Wolfe WG, et al. “Prophylaxis of Pulmonary Embolism.” Major Prob Clinical Surg. 1980; 25:96-111
  •  Tsapogas MJ, Miller R, Peabody RA. “Detection of Postoperative Venous Thrombosis and Effectiveness of Prophylactic Measures.” Arch Surg. 1970; 101:149-54
  •  McLachlin AD, McLachlin JA, Jory TA, et al. “Venous Stasis in the Lower Extremities.” Annals of Surg. 1960;152(4):678-83
  • Written June 2020 | Page last updated April 2022


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