Deep vein thrombosis and pulmonary embolism: Risk factors, symptoms, and diagnosis

Deep vein thrombosis is a serious but preventable medical condition in which blood clots occur, usually in veins in the lower leg, thigh, pelvis, and sometimes arms. It is treatable, but it can cause illness, disability, and death.

It is often underdiagnosed, so it is important to seek medical care if symptoms appear.

Pulmonary embolism (PE) is often associated with deep vein thrombosis (DVT). In PE, blood clots from DVT break off from vein walls and travel through the heart to the pulmonary arteries. If a PE happens, the lungs and other organs can be damaged, and death can occur.

These conditions can result when the blood clot is in the deep veins of the pelvis or thigh region. Blood clots that form in veins closer to the skin’s surface, known as superficial venous thrombosis, do not result in a PE. It is also possible to have a PE without DVT.

Risk factors


When blood cells clump together, this can form an embolism.

Anyone can develop DVT and PE. Many factors can contribute, but having multiple factors at once can increase the likelihood that a blood clot will occur.

Some common factors that may increase the risk of DVT and PE include:

  • Injury to a vein caused by a fracture, muscle injury or major surgery
  • Sluggish blood flow or lack of blood flow due to bed rest, limited movement, sitting, and crossing legs for a long time, and paralysis
  • Increased estrogen from birth control pills hormone replacement therapy, or pregnancy
  • Cancer and cancer treatments
  • A personal or family history of DVT and PE or clotting disorders
  • Obesity
  • Central venous catheters
  • Varicose veins
  • Venous insufficiency in the lower extremities.

Symptoms

The Centers for Disease Control and Prevention estimate that up to 900,000 people in the United States are affected by DVT, PE or both, although the exact number is not known. Women are more likely to be affected by PE than men. Since anyone can suffer from DVT and PE, it is important to know the warning signs and symptoms.


If an embolism reaches the lungs, this is called pulmonary embolism.

A person with DVT can have no symptoms at all, but if a patient experiences any symptoms and is also exposed to the risk factors mentioned above, they should seek medical care as soon as possible.

Symptoms include:

  • A feeling of cramping in the calf
  • Swelling, pain, and tenderness in the extremities, especially on one side
  • Redness of the skin usually associated with the swelling, pain, and tenderness described above.

A PE can occur with or without symptoms of DVT. PE can be extremely serious. If any of the following signs of PE occur, the patient should see a doctor immediately:

  • Difficulty breathing
  • Irregular or quickened heartbeat
  • Chest pain or discomfort, usually brought on by deep breaths
  • Coughing up blood
  • Low blood pressure, fainting, and feeling light-headed
  • Increased anxiety or nervousness.

Diagnosis

If a patient contacts the doctor with the symptoms of DVT or PE, they will undergo tests and the physician will make a diagnosis. Doctors usually use diagnostic imaging tests which are not invasive or uncomfortable.

A venous ultrasound examination can pinpoint blood clots in veins, and a rapid-speed chest CT scan can be done to look for blood clots in the arteries of the lungs.

Another test that identifies how well oxygen is being transferred to the lungs is a VQ scan for the lungs.

MRIs are less common in these cases, but they may be used to evaluate the veins in the pelvis.

A blood test called the D-dimer test can be done to determine if there is any excess blood clotting in the body. If it is negative, the chance of having a DVT or PE is very low. However, a positive test does not necessarily indicate a serious problem, as it could refer to something as simple as blood clotting in a healing skin wound.

Blood tests can also be done to detect prothrombotic state, also known as a clotting disorder. These tests are very expensive and the results can take several days. Normally, they are only used if a patient has a DVT or PE and there is concern about a clotting disorder, or if a patient is being screened for a clotting disorder because they have a family history of DVT or PE.

Treatment

It is very important to catch and treat DVT before it turns into a PE. A doctor will discuss and prescribe a treatment strategy that should decrease the blood’s ability to clot.

Anticoagulants, or blood thinners, are the most commonly prescribed medication for patients suffering from DVT or PE. They do two things. They decrease the ability of the blood to clotting, and they stop existing blood clots from enlarging.

Blood thinners do not break up existing blood clots, however. They only interrupt the clotting process so that the body can break down the clots through its normal mechanisms.

Patients can take anticoagulant medication in the form of pills, an injection or intravenously. Usually patients are instructed to continue oral medication for about 6 months, but every person is different.

Factors that affect treatment, include:

  • Pregnancy in women
  • Short-term blood clot risk versus long-term risks
  • History of blood clots
  • Other pre-existing illnesses.

Patients who are unable to take blood thinners because of a high risk of bleeding may need a vena cave filter. This filter is inserted into a large vein in the abdomen called the Inferior Vena Cava to catch blood clots before they can cause PE. The downside is that they do not stop new blood clots from forming, and sometimes clots can pass around the filter through smaller veins or form on the filter, break off, and still reach the lungs.

In severe cases of DVT, a vascular surgeon has two options. One is to access the affected vein and either remove the blood clot in a surgery known as thrombectomy. The other is to give thrombolytic medications or “clot busters” at the site of the DVT to try and dissolve it.

Treatment for PE also usually involves anticoagulants as described above for treatment of DVT.

In the case of a life-threatening PE, the doctor may prescribe thrombolytic medication, which breaks down the blood clots. This can be dangerous, as it may lead to bleeding in other parts of the body, such as the brain and the gastrointestinal tract. Doctors must decide on a case by case basis about giving this medication.

In rare cases, a surgeon may need to remove the blood clot from the lungs in a procedure known as an embolectomy. This is also a very risky procedure, and it would only be used as a last resort.

Prevention

People can reduce their risk of developing DVT and PE by staying healthy and managing their weight, avoiding a sedentary lifestyle, and talking to a doctor if there is a family history of clotting disorders.

Some simple rules can help to prevent DVT and blood clots.

These include:

  • Taking activity breaks if sitting for a long period of time, for example, over 4 hours. On a plane, passengers can walk up and down the aisle every 2 hours
  • Moving as much as possible, even if confined to bed rest
  • Doing seated exercises like leg raises, tightening and loosing leg muscles and doing heel and toe lifts
  • Wearing and compression stockings
  • Using anticoagulant medication, if appropriate.

People with a family or personal history of blood clots should pay attention to signs and symptoms that could indicate DVT or PE. It is important to keep moving, and avoid being still for long periods of time, to lessen chances of DVT and PE occurring.

Source: Deep vein thrombosis and pulmonary embolism: Risk factors, symptoms, and diagnosis

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