FAQs

This depends upon age, health, and underlying medical conditions, as well as the cause of the PE.

One-third to two-thirds.

The risk varies depending on the location of the clot. The risk for a PE increases the higher up in the leg the DVT occurs. For example, a calf DVT has a lower risk of breaking off and becoming a PE than a clot behind the knee or one in the groin or pelvic veins. Essentially, the larger the vein with the clot, the greater the risk of developing a PE.

A DVT is often the source of a clot that travels to the lung arteries and becomes a PE.

A pulled calf muscle usually gets better in a day or two. Another sign of a DVT is bluish or reddish skin discoloration, and skin that is warm to touch. These other signs do not usually happen with a pulled muscle. Learn more about DVT diagnosis.

Yes. PE mimics many other diseases and is particularly difficult to diagnose. Learn more about a PE diagnosis.

To rule out pneumonia, another common cause of chest pain and breathing difficulty. Learn more about PE diagnosis. 

It is the best current non-invasive technique for detecting a PE. Spiral CT (computed tomography) imaging is a new non-invasive technique being developed and has potential for replacing the VQ scan. Read more about PE diagnosis.

If a VQ scan does not identify a clot, but one is still suspected, a pulmonary angiogram is performed. A catheter is threaded through a vein in the groin, passed through the heart, and into the pulmonary artery. Contrast dye is then injected and X-rays are taken to monitor the blood flow in the lung. The angiogram will give a definite diagnosis as to the presence of a clot. Occasionally, an echocardiogram will show abnormalities in heart function, particularly in the right ventricle, as it meets resistance in pumping blood into the lungs. Learn more about PE diagnosis.

Most often, ultrasound is used to diagnose blood clots in the leg veins. This is a non-invasive test. If the results are not definitive, then venography (an invasive test using contrast dye) or MRI (magnetic resonance imaging) may be used. Learn more about DVT diagnosis.

If you are having unusual chest pain, it is always suggested to call 911 and not get into monitoring yourself.

It can be a good idea to monitor your own SpO2, but some patients don’t want to deal with the anxiety that comes with checking it. Monitoring it is a reasonable thing to do, but not necessary.

Your pulse rate, also known as your heart rate, is the number of times your heart beats per minute. A normal pulse rate ranges from 60 to 100. You should know your usual pulse rate. People who exercise frequently tend to have lower pulses. A rate over 100 in conjunction with chest pain or shortness of breath should be taken seriously, and you should seek immediate care.

The SpO2 reading on a pulse oximeter shows the percentage of oxygen in someone's blood. A reading over 95 is normal. Patients should be concerned when it gets under 90.  Anything below 90 is not normal and you should seek immediate care.

Anticoagulants may make you bleed more and can lead to changing menstrual products every 2 hours or less and often subsequent iron deficiency anemia.

No. Contact your doctor to make sure it is a clot. Anticoagulants prevent clotting, but can cause serious bleeding, so they should not be taken without a doctor’s exam and order.

No, focus on prevention and staying active. Take steps to maintain a healthy weight, walk aisles on airplanes, and do not sit too long when driving an automobile. Read more about blood clot prevention.

Nattokinase has not been approved by the FDA, and contrary to claims on the internet, it should not take the place of an anticoagulant. While one study shows that a nattokinase supplement lowers the risk of blood clots after long plane flights, optimal doses of nattokinase have not been set for any condition. Quality and active ingredients in supplements may vary widely from maker to maker. This makes it very hard to set a standard dose. It is advised to steer clear of this product for now.

They are fine in moderation and are unlikely to contribute to bleeding, however they are not vetted by the FDA. It is important to be very cautious taking them alongside anticoagulants. Over the counter medications like gingko, ginseng, vitamin E, fish oil can all potentiate anticoagulants (make them more powerful).

Wearing a medical alert ID bracelet can be a good idea so that those helping you in case of an emergency will know that you are on an anticoagulant.

Headache is the most serious sign of hidden bleeding, but you may also notice blood within the stool or urine.

Some side effects of anticoagulants are bleeding and bruising – so be careful with blood trauma and hitting your head, knee, etc. If you have hemorrhoids, you might bleed more.

Similar to a home device to prick your finger to measure glucose, home monitoring for warfarin consists of a small device used to measure your INR with a finger stick as opposed to going to the lab and having blood drawn from a vein in your arm.

International Normalized Ratio (INR) is the specific blood test used to measure the time it takes for blood to form a blood clot. This is called a prothrombin time test, or protime (PT). The PT is reported as the International Normalized Ratio (INR). The INR is a calculation based on results of a PT test and is used to monitor individuals who are being treated with the anticoagulation medication warfarin. INR tests are used instead of the PT because the INR is corrected for the strength of your blood clotting tissue. INR is also used to standardize the method used across all labs to lead to the most accurate results.

• If a person’s INR is too low, blood clots may not be prevented
• If a person’s INR is too high, they may experience uncontrolled or dangerous bleeding.

A balanced, healthy diet is always recommended, of course, but you can eat what you normally enjoy if you do so consistently. It is okay, and encouraged, to make the change to a healthier diet if you work with your healthcare provider to monitor your INR and make sure that you are becoming consistent with your diet. Some of the healthiest foods that you can eat, including foods like broccoli and spinach, are high in vitamin K. You might read or be told that you need to be aware of your vitamin K intake, because vitamin K can interfere with how warfarin works or that it will make it less effective. It’s always very important to understand how different things, like food, might affect how your medication works. However, if you eat these very healthy foods that are rich in vitamin K consistently – in the same amounts over time with no sudden changes – you can enjoy the wonderful nutritional benefits they provide as part of a healthy diet. You should talk with your healthcare provider before making any changes in what you eat. Most doctors would rather change your dose of anticoagulant than your diet.

Changes in perception of hot and cold are highly individual, but the thickness or viscosity of our blood has nothing to do with how we experience the temperature, therefore an association does not seem definitive.

Yes, It’s a known side effect of all anticoagulants but mainly with warfarin. To fix this, you would usually switch to another class of anticoagulant if the hair loss does not improve. Occasionally Coenzyme Q can help if the hair loss is warfarin related.

Vitamin E is a mild anticoagulant, and doses more than 400 units should be avoided.

Share your medical history with your doctor or medical team, make sure they know what anticoagulant you are on and that there is a plan in place to help prevent blood clots when you are in the hospital and when you return home. You need to see your doctor at least two weeks before surgery. Depending upon whether the surgery is major, or minor will determine the strategy for managing your anticoagulants. If the surgery is minor the doctor may not stop your anticoagulation at all. If the surgery is major, you will have to be removed temporarily. If a blood clot was 3+ months ago, generally anticoagulants will be stopped (most are 48 hours in advance) and can be started again after the surgery. Some patients are okay being off their anticoagulant and some are not. Most of the time a plan for surgery is made by assessing a patient’s risk factors. Check out NBCA’s pre-surgery checklist for hip and knee replacement patients. Learn more about managing anticoagulants before, during, and after medical procedures. General guidelines have been made that everyone is put on a low dose of anticoagulants for 2 weeks after a knee replacement, one month after a hip replacement, and variable times after hip fractures. Blood clot risk increases with anything that involved trauma or orthopedics.

Anticoagulants can be stopped without any change in dose. Their effect lasts only for a few days.

Patients can get tired of taking any medicine. This is a decision you should talk to your doctor about, because stopping your anticoagulant increases your risk of stroke and developing another blood clot.

This concern is common, and you should discuss your worry with your doctor. Try to concentrate on your freedom from taking pills that need blood testing. Doctors base the decision to stop anticoagulants on many factors such as what caused your clot, where it happened, and what your personal and family history of clots is. There is a lot of thought in their decision.

As directed by your doctor. Please do not cut a tablet as they are not scored; i.e., often the dose after 6 months is reduced 50% so if you are taking 5 mg of Eliquis twice a day and you are asked to reduce to 2.5 mg twice a day you will need a new prescription for 2.5 mg twice a day; same thing with 20 mg Xarelto daily being reduced to 10 mg a day.

If taking your medication as prescribed, and you did not miss any doses, the chance that you will re-clot is only 1-2 % at most. If you ever develop a blood clot when you are on anticoagulants, 3 most likely explanations are, 1. You have not been compliant with your medication, 2. You did not take the drug correctly i.e., you did not take with food, or 3. You are taking other medication which interfered with the anticoagulant. A good example of drug interference would be anti-seizure medication.

It is not unreasonable to check the complete blood count (CBC) and comprehensive metabolic panel (CMP) 1 – 2 times a year. If you are on coumadin you will need frequent blood testing about every 3 weeks. If you are on a DOAC like Apixaban or Rivaroxaban you will need blood testing less frequently (maybe every 6 months to make sure your kidney function is stable).

Yes, anticoagulants can have issues with other medications. Check with your doctor before getting prescribed anything like NSAID. Xarelto and Eliquis can react with certain seizure medicines, HIV medicines, anti-fungal medications, and TB medicines. There are very few other interactions. However, you should not take Xarelto with Paxlovid since it has an HIV medicine Ritonavir.  With Apixaban you should use half dose. warfarin (Coumadin) has many interactions, which is a good reason to use DOACs if you can for blood clots involving the legs and lungs.

There are some reversal agents for anticoagulants: Idarucizumab (reversal for dabigatran) & and Andexanet (reversal for apixaban (Eliquis), rivaroxaban (Xarelto), and (off-label) enoxaparin (Lovenox, and generics) in patients with active major bleeding. These are rarely used except for major life-threatening bleeds involving the brain or GI tract.

Usually, you would decide this based on if the blood clot was provoked or unprovoked and whether on-going risk factors are present such as obesity (body mass index >30) or being above the age of 55. Permanent risk factors or unprovoked blood clots are most likely to be treated long term because they have the highest rates of recurrence.

Talk to your healthcare team about which medication is right for you. Usually a direct anticoagulant (DOAC) such as Eliquis (apixaban) or Xarelto (rivaroxaban) is prescribed over warfarin (coumadin) as they are not affected by your diet nor most medications like warfarin. They also do not require periodic blood draw monitoring, but one exception is APAS. Eliquis is typically prescribed if there is a perceived higher bleeding risk i.e., menstruating female or if the patient has renal failure while Xarelto is preferable due to daily dosing instead of twice a day with Eliquis. Endoxaban and Dabigatran (Pradaxa) are other DOACs that do not require monitoring. Regardless of what anticoagulation medication is chosen, the treatment goals should include:

• Stop an existing clot from growing
• Preventing the formation of a new clot in other vein segments that could break off and travel to the lungs and become a PE
• Avoiding or minimizing any long-term complications

There are three main anticoagulants: rivaroxaban (Xarelto), apixaban (Eliquis), dabigatran (Pradaxa which is less common). Potential side effects include:

• An unfamiliar headache
  • While you will notice bleeding from your GI tract, your nose, and your skin; you may not realize that an unfamiliar headache can be a sign of bleeding in the brain so if you get an unfamiliar or more severe than usual headache you should contact your doctor
• Blood in your urine or stools
• In women, heavy bleeding during a period or excessive vaginal bleeding during the 6-week post-partum period
• Severe bruising
• Prolonged nosebleeds (lasting longer than 10 minutes)
• Coughing up blood
• If you have hemorrhoids, you might bleed a little more
• Learn more about Warfarin or Heparin.

These medications do not actually “thin” the blood, they do slow the body’s ability to form new clots, keep existing clots from getting bigger, and they prevent clots from travelling or embolizing.

Make sure to tell your entire medical team, including your primary care physician and other providers like your dentist. Every dentist handles anticoagulants differently.

This is a decision you make with your doctor, based on your health history and what works best in terms of your ability to take your medicine, your ability to get to a lab for blood tests, and what the medication costs. The main safety step is to take the dose at the right time your doctor tells you and do not skip or double doses.

Nothing. These terms can be used interchangeably.

The majority of patients do not have a repeat blood clot. However, risk is higher than for the general population whenever you had a clot. The degree of increased risk depends upon where the clot was, how many you clots you had, family history of blood clots, presence of blood clotting disorders, and any underlying medical conditions.

Someone should go over your medications, especially the anticoagulant prescribed, and the risk of bleeding associated with it. They should also advise you on when you need to schedule a follow up visit, how to take your medication, and how often to take it. Different anticoagulants have different follow up protocols. If you are on Coumadin, you will likely have to go in every 2 to 3 weeks because that drug is subject to variation and there are very narrow limits between what is effective and what is too much or too little.  However, if you are taking one of the direct oral anticoagulants (DOACs) such as rivaroxaban, apixaban, or dabigatran then you will not need to go in frequently. Someone should also talk to you about any potential drug interaction with your anticoagulant and how to handle high risk situations like air travel, long automobile travel, and what kind of activity you can be involved in without risk for hurting yourself.

About one-third to one half of patients experience some form of long-term complications after their blood clot, including but not limited to:

• Post-thrombotic syndrome: persistent swelling, pain, discoloration of the skin in the affected arm or leg; and rarely the skin can break down (ulceration)
• 2-4% of PE patients will have chronic lung damage (thromboembolic pulmonary hy­pertension)
• Further episodes of clotting
• Anxiety and/or depression

While not a long-term complication, once someone has a blood clot, they have an increased risk of developing another one.

Shortness of breath, fainting, or chest pains (particularly pains that worsen with coughing or change in position) are the three most worrisome signs. Learn more about the signs and symptoms of a pulmonary embolism.

Swelling and pain. It often feels like a persistent "charley horse," or cramping in the calf. A sensation of fullness/pressure/swelling/tightness occurs, especially when going from sitting to standing. It is also described as an odd pulling sensation or tingling that doesn't go away. Learn more about the signs and symptoms of a blood clot. 

You want to make sure the asthma is well controlled. It can worsen after a PE. You should maximize your normal asthma regiment or take steroids that can help with the pain from pulmonary infarction.

If you feel very short of breath you should immediately see your doctor. However, after a PE, you may have lung infarction/scarring/tissue damage which can affect breathing for some time. Most pain should go away in a couple of days, but shortness of breath can last for weeks. If symptoms do not go away within a few weeks, or if they worsen, you should call your doctor.

It is common to have leftover swelling in the leg after the initial treatment of a blood clot in your leg (DVT). When you wear graduated compression stockings (pressure stockings that are tighter around your ankle and get looser as they move up your leg) daily, they help increase blood flow in the legs and reduce swelling. There is a complication of DVT called post-thrombotic syndrome (PTS) that has many of the same symptoms of a DVT and is due to damaged valves. This is more common in blood clots experienced in the upper part of the leg.

Over time, the body will re-model the fibrin clot (an insoluble protein that is produced in response to bleeding and is the major component of the blood clot) termed “fibrinolysis” with retraction of the clot into the blood vessel wall, this happens for most blood clots. That is why it is uncommon to obtain a repeat CT scan of the lungs particularly since over 4-12 weeks the chest pain and shortness of breath usually resolves for most patients.

Some patients will be fine without pain medication or have adequate pain control with acetaminophen (i.e., Tylenol). If that is inadequate, a short course of anti-inflammatory medication may be prescribed but typically the non-steroidal anti-inflammatory drugs (NSAIDs i.e., Aspirin, Ibuprofen, Naprosyn) used for inflammation will increase the bleeding risk by affecting the platelets while on anticoagulant medication to prevent further clots. In cases like that, your provider may prescribe Celebrex which does not affect platelet function unlike the NSAIDs. It is also important to have a low threshold for calling the doctor since symptoms cause frequent anxiety.

You can take them in moderation, and there are many different options out there. This question is a good one to consult with your doctor on. Some medications pose higher risk than others and some can contribute to bleeding. Tylenol in low doses is okay but in high doses can make Coumadin more powerful. When on full dose anticoagulant you should only take anti-inflammatory Aspirin products like Ibuprofen or Naprosyn sparingly and only if you are not having any bleeding at that time like bruising or heavy menses. If you are ever on half dose anticoagulant, then these anti-inflammatory medications can be used more frequently.

Usually, a follow up scan is done if symptoms do not improve between 3-6 months and/or when stopping the anticoagulant to have a new baseline.

Heat, not ice, may help reduce the associated muscle spasm and relieve some of the inflammation. It is best to use wet heat instead of dry heat because wet heat penetrates deep tissue faster than dry heat to provide pain relief and reduce tissue damage.  

This is never normal. 1 in 10 patients will cough up blood. If you are coughing up blood it could be due to high pressure around the lung and can worsen on an anticoagulant. Blood clots usually don’t leave a scar in the lung, and pain is usually associated with pulmonary infarction.

Most of the time there will be no damage. The two places you could have lasting issues are in your leg and in your lung.  Damage in the leg would be from both the blood clot and the destruction of the valves that move blood along and cause swelling in the leg.  Most of the time this is just an inconvenience, but if you get significant swelling it may prevent you from doing a job where you must stand up repeatedly.  You may need to wear compression stockings to squeeze the blood back to the upper part of the body. As far as the lungs are concerned, 96% of the time there will be no serious damage, but 3 to 4% of patients develop post thromboembolic pulmonary hypertension where you might have some continued shortness of breath that requires a specialist to repair the damage done to the vessels in the lungs.

• After PE: Shortness of breath and mild pain or pressure in the lungs are common. You are likely to notice pain when you exert yourself, during physical activity, or whenever you take a deep breath. Shortness of breath gets better over time, and exercise helps you use your breath more efficiently. These symptoms should resolve in several weeks.
• After DVT: Post-Thrombotic Syndrome (PTS); persistent swelling, pain, and discoloration of the skin in the affected arm or leg. These symptoms may persist to some degree and are long term in one third to half of cases. Wearing knee high compression stockings for the first 3 months may reduce this risk.

It takes around 3 months to complete active treatment of VTE, although recovery time varies per individual, so there is no standard for how long it will take to recover. Download NBCA's New Patient Guide to learn more about the blood clot recovery timeline.

Yes, athletes can make a full recovery with DVT, PE and lung infarction. Infarction shouldn’t cause reduction in lung function. Most athletes (if they don’t get CTEPH) can make a full recovery. If you are returning to a contact sport and are on an anticoagulant– you may need to reassess your activities. For example, if you like to play basketball you should not drive to the basket or jockey for rebounds. Make sure to avoid trauma and falling at all costs. If you are an athlete seeking support, you can learn more about NBCA’s Sports and Wellness Institute and join our Team Stop The Clot® Facebook Support Group.

Exercise does not speed up clot dissolution. You can immediately resume exercise once pain and swelling improve. Mild to moderate activity after a DVT in the leg will not increase your risk of dislodging the clot to the lungs.

Moderate exercise such as walking or swimming is recommended. Returning to your normal exercise routine depends on your physical condition before the clot and the severity and location of your clots. Exercise increases circulation, reduces symptoms of venous insufficiency, and will make you feel invigorated. Aerobic exercise may increase lung function after a PE, although you don’t want to push through any pain.

It is essential, within the constraints of your physical condition. Exercise increases circulation, reduces symptoms of venous insufficiency, and will make you feel invigorated. Aerobic exercise may increase lung function after a PE.

Alcohol in moderation is fine, it is recommended to limit consumption to no more than 2 drinks at a time. (1 drink = 1 beer, or 1 glass of wine, or 1 cocktail, or 1 shot.)  Ask your healthcare provider if alcohol consumption is okay for you.

In general, hot tubbing is fine. You need your doctor’s approval when having a massage or going to the chiropractor when a clot is still present. It is important to be careful with any soft tissue in an area where there is or was a clot.

It is not recommended to get tattoos if you are on an anticoagulant, as you could get severe bruising and possible severe infection, but if your physician feels that it is safe to hold your anticoagulant, you may be able to get a tattoo after 3-6 months of treatment.

Rides without extreme acceleration/deceleration are fine. It would be best to wait until your acute symptoms have subsided.

Anticoagulants may make you bleed more and can lead to changing menstrual products every 2 hours or less and often subsequent iron deficiency anemia.

Pregnancy increases risk for developing blood clots. Work closely with your healthcare provider to manage it successfully. Usually, enoxaparin injections are prescribed while pregnant and continued during the post-partum period. In some cases, a patient may be switched to warfarin during the 6-week post-partum time.  Warfarin is safe if breastfeeding. If you have had a hormone related or idiopathic (unprovoked) blood clot you will likely take low molecular weight heparin during your entire pregnancy and 6 weeks post-partum.  You will need to discuss with your provider whether you want to start it prior to becoming pregnant or when you discover you are pregnant. Read more about pregnancy and blood clots.

There are many different options for birth control. Those who have had a blood clot should absolutely avoid estrogen-based birth controls. Non-estrogen-based birth controls include IUD’s (Mirena, Lileta, Kyleena, Skyla), Mini Pill, Implant, Copper IUD, Condoms, Spermicides, Diaphragm, Sponge, Tubal Ligation, or Vasectomy. The only progestin only contraceptive that should be avoided is the Depo-Provera injection. Learn more about birth control and blood clots.

It is uncommon that shortness of breath would affect your sexual performance, however the anxiety associated with the blood clotting event may make it harder for you to relax which could affect your sex drive. Females should be aware that occasional bleeding can occur during sexual intercourse if they are on an anticoagulant.

Most of the time the physical effects of the clot should not affect your home and work life unless you had a major clot in the lung (pulmonary embolism), you are short of breath, or you cannot accomplish household and work tasks. The more likely factor to impact your home and work life would be the psychological reaction. You should not hesitate to seek out help if you feel that you cannot concentrate or do your work.

Yes. In an automobile, stop every hour or so and walk for several minutes. On a plane, try to sit where you can stretch your legs (aisle seat, exit aisle, bulkhead seats, business class, etc.). Periodically, get up and walk the aisle(s) for several minutes. It is also a good idea to wear compression stockings when traveling.

This is something you absolutely need to discuss with your doctor. This has to do with numerous factors including how severe the event was and how much anxiety you are having.  If you are feeling better, you can return to work when you feel comfortable.

You can lower your risk of a blood clot by making a few lifestyle changes. These include giving up smoking, increasing exercise, and losing weight if you're overweight, aiming for body mass index <30. When it comes to exercise, you don’t have to resort to extreme workouts—regular, gentle physical activity like walking is a great way to promote good circulation. If you are recently diagnosed, discuss with your physician whether physical activity is appropriate for you, how much activity is recommended, and how soon you can begin. Physically, do only what is comfortable. You will not speed up recovery by pushing yourself aggressively through symptoms of pain and swelling. But you also will not make things worse by being active.

Blood clots can skip a generation. If they are in your family, you could be tested for thrombophilia. If a known thrombophilia isn’t found, it doesn’t mean you don’t have a blood clotting disorder. There are many thrombophilia disorders not yet identified.  Read more about the genetics of thrombophilia.

Ideally testing is done when not on anticoagulant medication.  

In general, testing is only ordered if the family member is in a potentially high-risk situation to developing a blood clot (i.e., major surgery or being prescribed an oral contraceptive). At that point, the family member who had the blood clot should be tested first so others know what to test specifically for.

If the blood clot is clearly provoked (i.e., surgery or oral contraceptives) such testing is not routinely done as it will not change management. If it was unprovoked, testing of the autoimmune condition termed Anti-Phospholipid Antibody Syndrome (APAS) is appropriate as the presence of APAS would require the use of Warfarin as opposed to a direct oral anticoagulant (DOAC). Also, if you become pregnant and have a family history of blood clots you might want to get tested to decide if you need prophylaxis during pregnancy.  

Anticoagulants are the usual treatment to prevent stroke. Warfarin or newer blood thinners such as rivaroxaban or dabigatran are effective for preventing strokes in patients with atrial fibrillation. They actually slow or stop clot formation, so are more “anti-clotting” drugs, even though they are known as blood thinners.

When your heart beats irregularly, blood may “pool,” or not flow forward. This increases the possibility of blood clots. Stroke is the most serious event when a blood clot travels to your brain.

Atrial fibrillation is an irregular or uneven rhythm in your heart. The top chambers of your heart, called the atria, do not beat in time with the bottom chambers, known as the ventricles. Patients often say they feel a fluttering, racing, or jumping in their chest when they have atrial fibrillation.

Once a cancer patient develops a first episode of DVT/ PE, he or she is typically treated with anticoagulants aka “blood thinners” (injections of low molecular weight heparin or with the oral drug warfarin) as long as the cancer is active, because the risk for another episode of VTE is high if anticoagulants are stopped. Reference: The Surgeon General’s Call to Action to Prevent Deep Vein Thrombosis and Pulmonary Embolism, 2008.

Clotting risk should be assessed in all patients with cancer. Whenever a patient with cancer is hospitalized, s/he should ask about treatment to prevent DVT or PE. Treatment to prevent blood clots should be routine in any hospitalized patient, and usually consists of injections of heparin or low molecular weight heparin. Compression stockings or pneumatic devices are also used to help prevent blood clots. Patients with cancer who are home and can move around have a lower likelihood of developing DVT/PE. However, patients should be aware of signs and symptoms of DVT/PE and seek immediate attention when they notice them.

Having surgery to remove the cancer, particularly abdominal and pelvic surgery increases risk. Being hospitalized, immobile, or having a central venous catheter placed (for chemotherapy or other reasons) also increases risk. Risk goes up as age increases, and having a family history of DVT/PE or a pre-existing inherited or acquired thrombophilia makes it more likely for a cancer patient to clot.

Yes, some chemotherapies are associated with a higher risk of blood clots. Some examples include Thalidomide and Lenalidomide to treat multiple myeloma, Avastin® to treat colon cancer, and certain chemotherapies that may be given in combination with others, including cyclophosphamide (Cytoxan®), chlorambucil (Leukeran®) and nitrogen mustard (Mustargen®). It is not well known why chemotherapy increases risk of DVT/PE, but it is suspected that this could be because they cause damage to blood vessels or reduce the production of proteins that protect us from clots. Women treated with tamoxifen to prevent or treat breast cancer are also at increased risk. Erythropoietin, which is sometimes used to treat anemia and improve quality of life in cancer patients receiving chemotherapy, may also increase the chance of developing a blood clot.

Yes. Cancers of the brain, ovary, pancreas, colon, stomach, lung and kidney have the highest risk of DVT/PE. Lymphomas, leukemia, and liver cancer are also more likely to lead to DVT/PE.

While this is not fully understood, it is thought that cancer may lead to tissue damage and inflammatory responses that lead to activation of the blood clotting (coagulation) system. Tumors also release chemicals which trigger clotting.

This does not happen often, because testing to detect cancer is done only in those patients who show signs that suggest cancer may be present, such as unexplained weight loss or infection. About 10% of people who have DVT/PE will be diagnosed with cancer within 12 months after a DVT or PE. In some cases, with blood clots that do not seem to have any known cause, there may be a need for a more extensive work-up to look for an underlying cancer.

Certain cancers increase the risk of a blood clot fourfold, and chemotherapy increases risk up to six-fold, so preventive use of anticoagulants is usually wise. Discuss this with your doctor.