Guide to Giving Subcutaneous Injections
Blood Clots and Anticoagulants
Blood clots can develop in the bloodstream when special proteins combine with blood cells called platelets. While they can help stop bleeding in response to an injury, some blood clots form without a good reason and don't dissolve on their own.
People with cancer have a higher risk for blood clots. It is estimated that up to 20% of patients with cancer develop venous thromboembolism (a condition that occurs when a blood clot forms in a vein) and 30% experience atrial fibrillation (an irregular and often very rapid heart rhythm that can lead to blood clots in the heart). The risk of a dangerous blood clot is often greatest for cancer patients during the first few months following a cancer diagnosis.
Surgery, hormone therapy, chemotherapy, tubes placed in veins to deliver treatments and certain cancer treatments that require hospital stay can also increase risk for blood clots. Left untreated, blood clots can be fatal and without treating atrial fibrillation the risk of stroke increases. Anticoagulant medications can help dissolve existing clots or prevent them from forming.
What are anticoagulants?
Anticoagulants or “blood thinning” medications are prescribed by doctors to prevent a blood clot from growing so your body can naturally break it down; they can also prevent new blood clots from forming. Anticoagulants are commonly part of treatment plans for cancer patients.
Doctors also give anticoagulants in lower doses to patients with certain high-risk cancers and after major cancer surgery to prevent blood clots from forming.
These medications come in a variety of forms, including oral, injections or IV infusions.
What conditions do anticoagulants treat?
One of the most common reasons patients take anticoagulation medication is venous thromboembolism (VTE). VTE is a medical condition that includes deep vein thrombosis and pulmonary embolism.
Deep vein thrombosis (DVT) is an abnormal blood clot that forms in a deep vein of the body. These blood clots most commonly occur in the legs. The blood clot can travel from the legs through the heart and into the lungs, causing a pulmonary embolism.
A pulmonary embolism (PE) occurs when a blood clot gets stuck in an artery in the lung, blocking blood flow.
Atrial fibrillation is another common condition that may require anticoagulation medication. This condition is an abnormal heart rhythm that can cause blood clots to form in the heart. Certain patients with this condition may need anticoagulant medications to help prevent a stroke.
What are the risk factors and warning signs of blood clots?
While blood clots can affect anyone, certain factors can increase risks. Common risk factors include:
- Surgery
- Immobility
- Previous VTE
- Trauma
- Cancer/chemotherapy
- Pregnancy
- Birth control medication containing estrogen
- Older age
- Obesity
- Smoking
Warning signs of deep vein thrombosis include swelling, redness, pain or tenderness, and skin that is warm to touch.
Warning signs of a pulmonary embolism include shortness of breath, chest pain, coughing or coughing up blood, and a fast heart rate.
Anticoagulant guidelines
If you are taking anticoagulants, call 911 or go to the nearest hospital emergency room if you experience any of the following:
- Signs of gastrointestinal bleeding (bright red blood in stool or dark, tarry stools)
- Signs of head bleeding (altered mental status, confusion, severe headache, drowsiness, slurred speech, sudden unexplained vomiting, numbness or weakness in a limb)
- Blood in the urine
- Coughing or vomiting blood
- Uncontrolled bleeding or extensive bruising
- A serious fall or hit on the head
- Chest pain or shortness of breath
- Redness, swelling, warmth or pain in a limb
- Other serious symptoms or changes in your health
There are several other guidelines for patients on anticoagulants:
- You must take your anticoagulation medicine as prescribed. Missed doses could result in blood clots or stroke.
- If you are taking a subcutaneous injectable anticoagulation medication, check your weight at least once a week and tell your health care team if you gain or lose more than 10 pounds.
- You may need to take this medicine for at least three months. Surgical patients are on a different schedule; after surgery, you may need to take anticoagulants for up to one month. You should not stop taking this medicine unless instructed by your provider or if there is a bleeding complication. Contact your provider for refills if needed.
- You may be told to stop taking this medicine before a medical procedure. If you have not been told to stop prior to a procedure, tell your health care team you are on an anticoagulant. You should also ask how to safely start taking the medicine again after the procedure.
- You should not take ibuprofen (Advil®, Motrin®), naproxen (Aleve®) or any other over-the-counter non-steroidal anti-inflammatory medicines unless approved by your health care provider.
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Pulmonary Embolism
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Deep Vein Thrombosis
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Atrial Fibrillation
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Blood Thinning Medicines to Avoid Before Surgery (English)
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Blood Thinning Medicines to Avoid Before Surgery (Spanish)
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Blood Thinning Medicines to Avoid Before Surgery (Chinese)
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Direct Oral Anticoagulants (English)
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Direct Oral Anticoagulants (Spanish)
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Warfarin or Coumadin (English)
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Warfarin or Coumadin (Spanish)
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Video: Atrial Fibrillation and Stroke Risk
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Video: Venous Blood Clot and Its Treatment
The risk of developing blood clots is somewhat higher among cancer patients. This is due both to the inflammatory nature of the disease itself and the therapies used to treat cancer.
Deep vein thrombosis (DVT) is one such type of blood clot. It forms in the veins found deep inside muscles and other tissues, and it can be fatal if left untreated.
Why are cancer patients more susceptible to DVT? And, can it be prevented? We asked breast medical oncologist Ajit Bisen, M.D., for insight.
Why are cancer patients at increased risk for deep vein thrombosis?
Our bodies have a natural ability to balance blood clotting with blood flow. But whenever you introduce a variable into the mix, it causes an imbalance that can lead to the development of blood clots, including DVT.
Cancer is considered a “hypercoagulable” condition because it’s more likely to lead to blood clots. That’s because both cancer and its treatment often create one or more of the conditions necessary for blood clot formation. Collectively, they’re known as the Virchow triad:
- a change in blood flow,
- a blood vessel injury, or
- a change in the composition of the blood.
Cancer causes inflammation, which can make blood more likely to clot. Tumors can cause blockages and issues with blood flow. And surgeries and radiation therapy can cause injuries to tissue, sometimes even at the microscopic level. So, any or all of these could contribute to DVT.
Where do cancer patients typically develop deep vein thrombosis?
The most common place is one of the legs, simply because gravity tends to make blood pool at the bottom of the body. But it can also develop in the arms, neck, chest or abdomen.
In cancer patients, DVT sometimes forms at the site of a chemotherapy port, too. It’s a type of catheter inserted into one of the deeper veins of the chest. It can cause injury to the vein and can affect blood flow, leading to DVT.
And, if the body identifies the port as a foreign object, it can activate the “coagulation cascade,” an assembly of proteins and clotting factors that normally converge on the site of an injury to stop the bleeding. This balance between bleeding and clotting happens at the site of any tissue injury.
Does deep vein thrombosis have any symptoms?
The most common symptoms of DVT among cancer patients are:
- arm or leg: swelling, redness and pain in the area of the clot
- abdomen: abdominal pain
- chemo ports: swelling or redness around the port
How is deep vein thrombosis usually found in cancer patients?
Sometimes, patients will come to the clinic reporting one or more of the symptoms described above. But often, it’s just an incidental finding on CT scans that are performed to stage cancer.
What are the biggest risk factors for deep vein thrombosis?
We divide DVT into two categories: “provoked” and “unprovoked.”
Provoking risk factors include:
- not getting up to move around very much during extensive travel
- major surgery causing vascular injury, prolonged hospitalization and/or limited mobility
- trauma fractures, such as a broken leg or rib
- malignancies requiring active treatment
- medications, such as estrogen therapy
- high body weight
- pregnancy
- smoking
- inherited conditions such as factor V Leiden, antiphospholipid syndrome and autoimmune disorders.
All of these may contribute in some way to an imbalance.
Unprovoked DVT has no clear explanation for its cause.
How is deep vein thrombosis treated?
If DVT is due to a clear, provoking reason that’s considered a transient risk factor, we’ll normally treat it for about 3 to 6 months with blood thinners. We have several different types to choose from. These help stabilize the blood clots and keep them from getting any bigger.
Quick-acting clot-busting medications called thrombolytics are not usually used unless you’re in a life-threatening situation, such as a stroke, heart attack, or a large pulmonary embolism. That’s when a blood clot dislodges from its original location and travels to the lungs, where it can block an artery. That condition is very dangerous and can sometimes be fatal.
If you have a persistent risk factor such as cancer, an autoimmune disorder, or chronic organ dysfunction, we’ll treat you for as long as the risk factor is present. In stage IV cancer patients, that could mean for the rest of your life.
When should you seek help for possible DVT?
Deep vein thrombosis can turn fatal very quickly by dislodging and traveling to the lungs, so notify your provider immediately about any new swelling associated with pain or redness. They may start you on a blood thinner right away.
But if you’re also experiencing shortness of breath, chest pain, lightheadedness or difficulty breathing, call 911.
What’s the one thing you want cancer patients and their caregivers to know about DVT?
Blood clots are a very common side effect of cancer. And aside from the cancer itself, they are the second most common cause of death among cancer patients. So, if you think you might be developing one, don’t wait. Contact your care provider right away and get it checked out.
Can deep vein thrombosis be prevented?
There are a few things you can do to reduce your risk of blood clots.
Sometimes, even otherwise healthy people will notice some ankle swelling if they’ve been sitting in the same position for a long time, like on a transatlantic flight. So, try to avoid long periods of inactivity or immobility. Get up and walk around frequently to keep your blood flowing, whether you’re in your car on a long trip or sitting at your desk or on the sofa.
If you have any injury to your legs or body, be vigilant about watching yourself for symptoms.
If you’re carrying excess body weight, look into weight loss programs.
And if you smoke, quit now. Medication and counseling are the best ways to do it. Call 1-800-784-8669 or text QUIT to 47848. Cancer patients can also enroll in MD Anderson’s Tobacco Research and Treatment Program.
Request an appointment at MD Anderson online or by calling 1-877-632-6789.
Subcutaneous Injections
You may be prescribed anticoagulant injections that need to be given at home. Learn more about how to perform at-home injections:
This video describes all types of subcutaneous injections including the use of prefilled syringes used for anticoagulation medication.
Questions about your anticoagulants?
If you have been given a prescription for anticoagulation medicine, it is very important that you follow the directions carefully when taking it.
If you are an MD Anderson patient and have questions about your anticoagulant medication, send your team a message in MyChart. We will respond to you within one business day. Each medical message goes to your physician’s nursing team to ensure messages are read in a timely manner.
If your concern is urgent, call your center and ask to speak to a nurse. After hours and weekends, call 877-632-6789 to talk with askMDAnderson nurses.