Neil A. Goldenberg, MD and Marilyn J. Manco-Johnson, MD
University of Colorado at Denver and Health Sciences Center The Children’s Hospital, Denver, and Mountain States Regional Hemophilia and Thrombosis Center, Aurora, CO
Deep-vein thrombosis (blood clots in the veins of the body; also called DVT) and pulmonary embolism blood clots in the lungs; also called PE) can occur at any age. Although blood clots occur more commonly in adults, about 1 in 10,000 children will be affected. The first month of life (especially in premature and other hospitalized infants) and the teenage years appear to be times of greatest risk for young people to develop blood clots.
There are some issues that are unique to young people who develop blood clots. For instance, young people with DVT or PE appear to have single or multiple genetic thrombophilia (excess clotting) traits more frequently than older adults, and this can affect the risk of a future blood clot in both the young patients and their family members. All people, including children and young adults, may develop a chronic of poor venous blood circulation called the post-thrombotic syndrome (PTS) following a blood clot in the arm or leg. PTS is often diagnosed when swelling and pain in the arm/leg develops with activities or when these symptoms persist over a period of months to years following the diagnosis. In severe cases of PTS, there may be skin breakdown as well as pain in the arm/leg while at rest.
What are the causes of venous thrombosis and pulmonary embolism in children and young adults?
DVT and PE in children and young adults can be caused by poor blood circulation (for example, during times of decreased mobility or vein constriction for a prolonged period), damage to the inner lining of veins (such as when a catheter is placed in a vein, or when certain drugs or toxins are circulating in the blood), and thrombophilia states. In children and young adults, a combination of these risk factors is often present at the time of DVT or PE. Also, in young people, genetic causes of thrombophilia may be important contributing factors to DVT or PE. Sometimes, however, the cause of DVT or PE in children and young adults remains unclear.
Research at some specialty centers in the U.S. is focusing on the discovery of new thrombophilia traits and other risk factors in these patients. How are venous thrombosis and pulmonary embolism diagnosed in children and young adults?
Signs and symptoms
DVT in young people may occur with a variety of signs and symptoms, depending mainly on the area of the body that is affected and the degree of blockage of the vein(s) involved. Unfortunately, in some cases of DVT and PE, signs and symptoms can be absent. When DVT or PE are found on scans in a patient who does not have (or does not recall) any signs or symptoms, it may be difficult to determine whether the clot is new or old, and this can affect treatment decisions.
Radiologic imaging tests (scans)
For DVT in an arm or leg, ultrasound or computed tomography (CT) is typically used. In some cases, a dye scan of the veins (venogram) or specialized magnetic resonance imaging (MRI) scan that allows detailed views of the vessels (MR venogram) may be required in order to be sure about the diagnosis. To diagnose clots in the brain, MR venogram or CT venogram is typically used. Suspected PE is confirmed by specialized CT scans or by a nuclear medicine scan called a “V/Q” scan.
Another critical step in the evaluation includes laboratory testing for thrombophilia. Thrombophilia testing for blood clotting risk factors can vary across treatment centers. In addition, because young people who develop DVT or PE often have an underlying illness, other laboratory testing relating to the underlying illness may be performed in order to monitor its course. Patients who have other signs and symptoms that could suggest an underlying rheumatologic condition (a broad category of medical disorders — including lupus, juvenile rheumatoid arthritis, and others — in which the body’s immune system is overactive) may have specialized testing to evaluate for these disorders.
How are venous thrombosis and pulmonary embolism treated in children and young adults?
In a child or young adult with newly- diagnosed DVT, the standard treatment is anticoagulation (blood thinner therapy). Blood thinners typically used include heparin, low molecular weight heparin and/or warfarin (Coumadin®). The blood- thinning effect of heparin and warfarin treatments are measured by blood tests in order to keep the level of blood thinning in a safe and effective range. In cases of acute DVT that is large and completely blocks blood flow from an arm or leg, special medicines or techniques to remove or break up the clot (thrombolysis) may be considered early in the initial treatment instead of routine anticoagulation (although later followed by anticoagulation).
How are venous thrombosis and pulmonary embolism treated over the long term in children and young adults?
Long-term management of DVT and PE is focused primarily upon: (1) safely preventing further blood clots; and (2) enabling the child/young adult to function as best as possible in school, work, family, and/or society. Prevention of further DVT or PE In an effort to prevent further blood clotting (including the worsening of an existing blood clot and the development of a new DVT or PE), most children and young adults with acute DVT or PE are treated with anticoagulation for at least 3-6 months. Some patients, such as those with certain thrombophilia states and individuals who have had multiple blood clots, may be prescribed anticoagulation over a longer period. In patients with particular underlying medical conditions, other treatments aimed at improving the underlying disorder may also decrease the risk of further blood clotting. For example, in patients with severe infections, antibiotic treatment is also given, and in patients with rheumatologic conditions, drugs to control the overactive immune system may also be used. To prevent a fi rst or subsequent DVT or PE, all patients and at-risk family members should also take care to avoid dehydration and smoking, and should adopt a regular aerobic exercise program.
Prevention and treatment of post-thrombotic syndrome (PTS) Enabling the child/young adult to function as best as possible in school, work, family, and/or society involves prevention and treatment of PTS. Clinical research studies in older adults have shown that daily continuous use of compression stockings on an affected leg or arm for a period of at least 1 year following the diagnosis of DVT can reduce the risk of developing PTS. Based on this knowledge, routine use of compression stockings should also be strongly encouraged for all young patients with DVT. In children and young adults with DVT, if PTS is severe and does not adequately improve with the use of compression stockings, or if chronic SVC syndrome is present (a syndrome of swelling of the head and neck due to blockage of a central vein in the upper body, called the superior vena cava), other options may be available.
For example, in some patients, procedures to restore or improve venous drainage may be possible. These procedures (including stenting, venous bypass grafting, and other techniques) are typically evaluated and performed by specialists in interventional radiology or vascular surgery.
Other practical considerations It is important to work with a knowledgeable team of healthcare providers, including blood clotting specialists from Hematology, in the care of the child or young adult with DVT or PE. Thorough evaluation of DVT and PE is often challenging, and both short-term and long-term treatment decisions can be difficult.
The identification of thrombophilia is an important component of this care, and is best guided by experts in blood clotting. A list of centers specialized in clotting disorders can be found at http://www.stoptheclot.org/learn_more/find_provider.htm.