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Deep vein thrombosis happens when a clot clogs a vein in the leg, preventing blood from returning to the heart properly, which can happen due to the person's older age, the presence of diseases that make the blood more viscous, hormone replacement with estrogen or having the leg immobilized for a long time, for example.
Thus, as circulation is impaired due to the presence of the clot, some symptoms may arise, the main ones being:
- Swelling in one of the legs, which increases over time;
- Sudden pain in one leg that gets more intense over time;
- Redness in the affected leg;
- Feeling hot when touching swollen leg;
- More visible veins in the skin due to greater dilation;
- Pain when touching the leg
- Skin of the affected area harder than normal.
There are still cases where the clot is very small and does not cause any kind of symptoms, disappearing on its own with time and without needing treatment. However, whenever venous thrombosis is suspected, you should go to the hospital to identify the problem and initiate appropriate treatment, as some clots can also move and affect important organs, such as the lung or brain, for example.
Symptom online test
If you think you may be developing venous thrombosis in your leg, select your symptoms and find out what your risk is:
- 1.Sudden pain in one leg that gets worse over time Yes No
- 2.Swelling in one of the legs, which increases Yes No
- 3.Intense redness in the affected leg Yes No
- 4.Feeling hot when touching swollen leg Yes No
- 5.Pain when touching leg Yes No
- 6.Leg skin tighter than usual Yes No
- 7.Dilated and more easily visible veins in the leg Yes No
Make an appointment with a specialist
What to do in case of suspicion
The diagnosis of thrombosis should be made as soon as possible, therefore, it is advisable to go to the hospital or emergency room whenever there is a suspicion of a clot in the leg.
Generally, the diagnosis is made from the evaluation of symptoms and some diagnostic tests such as ultrasound, angiography or computed tomography, which help to locate where the clot is.In addition, the doctor also usually orders a blood test, known as a D-dimer, which is used to confirm or exclude the suspicion of thrombosis.
Who is most at risk for thrombosis
There are greater chances of having a deep vein thrombosis in people with:
- History of previous thrombosis;
- Age equal to or greater than 65 years;
- Diseases that make the blood more viscous, such as Waldenstrom's macroglobulinemia or multiple myeloma;
- Behçet's Disease;
- History of heart attack, stroke, congestive heart failure, or lung disease;
- Who had a serious accident with major muscle injuries and bone fractures;
- Who had surgery that lasted more than 1 hour, especially knee or hip replacement surgery;
- In women on estrogen replacement hormone.
In addition, people who need to be immobilized in bed for more than 3 months are also at increased risk of developing a clot and experiencing deep vein thrombosis.
Already pregnant, women who have been mothers for a short time or women who are taking hormone replacement or using some hormonal contraceptive method, such as the pill, also have a slight risk of thrombosis, as hormonal changes can interfere with the blood viscosity, making it easier for a clot to form.
See the 7 most common side effects of hormonal drugs like the pill.
COVID-19 increases the risk of thrombosis?
According to some studies, infection with COVID-19 increases the risk of developing clots that can result in deep vein thrombosis or pulmonary embolism. This seems to happen especially in the most serious cases, due to the intense inflammatory process that the virus causes in the body and which ends up increasing the production of substances responsible for blood clotting.
To reduce the risk of clots, the Brazilian Society of Thrombosis and Hemostasis  recommends that people hospitalized for COVID-19 make prophylaxis with anticoagulant drugs. Regular blood tests are also recommended to assess different parameters, such as the number of platelets, fibrinogen, but mainly D-dimer, since the increase in the value of D-dimer seems to be directly related to the appearance of clots. Understand better what D-dimer is and how it relates to clot formation.
Does the COVID-19 vaccine cause thrombosis?
After several studies, entities such as Anvisa and the European Medicines Agency reported that vaccination against COVID-19 may slightly increase the risk of developing clots and, consequently, causing thrombosis. However, this risk appears to be only 1 person in 175,000, which is a much lower rate than the risk of developing thrombosis after catching COVID-19, which is around 15%.For this reason, vaccination continues to be recommended and considered safe.
Among the main vaccines used, the one with the highest number of thrombosis cases so far were the adenovirus vaccines, such as AstraZeneca and Janssen. In addition, there have been reports of thrombocytopenia (decreased platelets) associated with thrombosis 4 to 52 days after the second dose of these vaccines, however these effects are rare and therefore vaccination is still recommended. Learn more about the side effects of COVID-19 vaccines.