Blood Clots (DVT/PE): What You Should Know

After a spinal cord injury, your risk of a dangerous blood clot is much higher than most people’s. Without preventive blood thinners, more than half of people with a new SCI get a clot, and clots are a leading cause of death in the first year (per PVA). The risk is highest in the first weeks, but it can stay high long-term.

There are two main worries. A deep vein thrombosis (DVT) is a clot in a deep vein, usually in the leg or pelvis. A pulmonary embolism (PE) is when a piece of that clot breaks off, travels to the lungs, and blocks blood flow. A PE can kill within minutes.

The good news: with a steady prevention plan, most clots can be avoided. Everyone with SCI needs a clear plan worked out with their care team.

🚨 Red Flags — When to Seek Emergency Care

Call 911 or go to the ER right away if you have any of these. They can start suddenly:

• Sudden shortness of breath, fast breathing, or a feeling you can’t get enough air.
• Sharp chest pain that gets worse when you breathe in or cough.
• Coughing up blood, or a new cough you can’t explain.
• A racing or pounding heartbeat, feeling faint, or a sense of dread.
• New swelling, warmth, redness, or a blue-purple color in one leg, ankle, or calf — compare it to the other side. Even with no feeling there, you or a caregiver may spot it.
• New leg pain, or new one-sided spasticity or autonomic dysreflexia with no clear cause.

Tell the ER team right away: “I have a spinal cord injury with paralysis. I am at very high risk for blood clots. Please check me for a DVT or PE with an ultrasound or CT.” If you take blood thinners or have had a clot before, say so. A PE can be quiet until it is serious, so do not wait to see if it passes.

Why the Risk Is So High After SCI

Clots form when three things line up. After SCI, you often have all three at once (per PVA):

• Slow blood flow. Working calf muscles normally pump blood back to the heart. With paralysis or less movement, blood pools in the leg veins.
• Stickier, thicker blood. Trauma and surgery change how your blood clots, and dehydration makes it worse.
• Damaged veins. The injury, surgery, or IV lines can irritate vein walls.

A few patterns help. Clots happen most often in the first two weeks after injury, and the risk stays highest over the first months. A leg DVT is more likely with a complete injury than an incomplete one, and more likely with paraplegia than tetraplegia. Clots in the lungs are not tied to those differences (per PVA). Even years later, the risk climbs any time prevention slips — a long flight, a hospital stay, new immobility, surgery, or dehydration.

How a Clot Is Found

If you have symptoms, your team will scan you rather than guess. A Doppler ultrasound is usually the first test for a leg or arm clot. It is accurate, painless, and needs no prep. If ultrasound won’t work, or a lung clot is likely, they may use a CT scan with dye, a contrast venogram (an x-ray with dye), or a VQ lung scan (per PVA).

Doctors usually do not test for clots in people with no symptoms. Ultrasound misses many silent clots, and routine testing has not been shown to prevent them. That is why knowing your own warning signs matters so much.

Daily and Ongoing Prevention

Work with your rehab doctor or SCI specialist to build a plan for your risk. Common parts:

• Squeezing devices and stockings. A device that squeezes your calves (“leg pumps”) is standard in the hospital after a new injury. Compression stockings support blood flow, especially when you sit for a long time. Take them off at night unless told otherwise (per PVA).
• Blood thinners. After a new SCI, these usually start as soon as it is safe and go for at least eight weeks. Low-molecular-weight heparin (such as enoxaparin), a small shot under the skin, is preferred over plain heparin; pill options exist too (per PVA). Never stop a blood thinner on your own.
• Movement. Even small, frequent ankle pumps, leg range-of-motion, and pressure reliefs help. Get out of bed or your chair as much as you safely can (per SCIRE Community).
• Fluids. Drink enough through the day. Dehydrated blood clots more easily.
• Don’t smoke or vape. Both harm circulation and raise clot risk, including marijuana (per MSKTC).
• Manage your health. See your doctor regularly and keep other conditions in check. Blood thinners are usually restarted any time you are in the hospital (per PVA).

Spotting a Clot When Feeling Is Reduced

Many people with SCI have little or no feeling in the legs, so the usual “calf pain” may be missing. Watch for other clues instead:

• Swelling that is clearly worse on one side than your normal.
• Warmth in one calf or thigh that you or a caregiver can feel.
• New or stronger spasticity in one leg.
• A change in skin color — redness or a blue-purple tint.
• Autonomic dysreflexia with no other clear trigger.

If one leg feels “off” compared to the other, get it checked the same day. Don’t wait for pain that may never come.

Travel and Long-Sitting Tips

Long flights and car rides raise clot risk for everyone, and more so after SCI (per PVA). Before and during a long trip:

• Wear your compression stockings.
• Sip water steadily; go easy on alcohol and caffeine.
• Do ankle pumps and leg range-of-motion every 30 to 60 minutes.
• Get up or shift position when it is safe.
• Ask your team ahead of time whether a single blood thinner dose before a very long trip is right for you — only under their direction.

Trip packing, flights, and hotel logistics: Traveling with SCI.

Other Things That Raise Your Risk

Beyond not moving, a few things add to clot risk. Tell your doctor about any of these so your plan can change (per PVA):

• Flying or other long, still travel.
• Having or developing cancer.
• Estrogen or hormone therapy, and birth control pills — the pill raises DVT risk (per MSKTC).
• Smoking or vaping.
• Pregnancy. If you have had a clot, ask your obstetrician about preventive medicine, compression hose, range-of-motion, and propping your feet up (per MSKTC).
• Surgery, a known trigger for DVT and PE (per MSKTC).

If You Have a Clot: Treatment and What Changes

If a clot is found, you will usually start blood thinners, unless bleeding is more dangerous than the clot. How long depends on the clot (per PVA):

• A clot in the leg: often 3 to 6 months.
• A clot in the lungs: often about 6 months.
• Repeat clots: sometimes lifelong.

Other options exist for certain cases. A “clot buster” (thrombolysis) dissolves a clot, or a procedure (thrombectomy) removes it. Both carry more bleeding risk, so they are not routine. An IVC filter is an umbrella-shaped net placed in the large vein in your abdomen to catch clots before they reach the lungs. It is used mainly when blood thinners are not safe. Removable filters often come out after about eight weeks, once the highest-risk time passes; if you have a removable filter in place under eight weeks, ask your doctor about removing it (per PVA).

Living on blood thinners. Know your bleeding signs: heavier periods, cuts slow to stop, bleeding gums or nose, or more nosebleeds. Call your doctor about any of these. Many everyday over-the-counter drugs change how thinners work, including aspirin, ibuprofen (Advil, Motrin), naproxen (Aleve), Alka-Seltzer, and Excedrin — clear every medicine with your doctor (per PVA). On warfarin (Coumadin), you need regular blood tests, and vitamin-K foods change the dose. Newer pills such as apixaban (Eliquis), dabigatran (Pradaxa), and rivaroxaban (Xarelto) have no food interaction. You can return to therapy and activity once treatment has started.

After a leg DVT, some people get post-thrombotic syndrome — lasting swelling, heaviness, aching, hardened or darkened skin, visible veins, or skin breakdown in that leg (per PVA). Tell your team about any of these. Ask for clear guidance on what to do if you bleed, need surgery, or become pregnant while on thinners.

What Many People Find Helpful

• Treat compression stockings as must-have gear, like your cushion or catheter supplies. Keep spares and a replacement schedule.
• Set a daily phone reminder for “ankle pumps and water” through the highest-risk months.
• If a caregiver helps, make sure they know how to put stockings on right — wrinkles or the wrong pressure can do harm.
• Keep a small travel kit: extra stockings, water, and an up-to-date medication list whenever you are out for more than a few hours.
• Carry a card listing your SCI level, that you are high-risk for clots, and your current blood thinner. It speaks for you in an emergency.
• Some people with high-level injuries keep a pulse oximeter at home to check their oxygen if they feel short of breath — only as an extra step, never instead of getting checked.

Evidence & Sources

Synthesized from PVA Consortium consumer guides, MSKTC factsheets, and SCIRE Community evidence summaries (retrieved 2026-06-24). See RESEARCH-SOURCES.md for complete provenance and cross-bucket details. The clinical detail on incidence, timing, prevention, diagnosis, treatment, and recognition in the SCI population draws mainly from the PVA Blood Clots: What You Should Know Consumer Guide.

Printable One-Pager Notes

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Blood clots are one of the few complications after SCI that can kill quickly and quietly. Steady prevention — squeezing devices, blood thinners when prescribed, movement, and fluids — works. Know your personal risk window and your exact plan. If anything changes in your mobility, medicines, or travel, ask your team whether your clot prevention needs to change. When in doubt about a symptom, get checked the same day.