Anesthesia and Blood Clots: What You Need to Know

Surgery and anesthesia change how your body moves and how blood flows. That raises the chance of a blood clot, especially deep vein thrombosis (DVT) in the legs or a clot that travels to the lungs (pulmonary embolism). You don’t need to panic, but you should know the risks, signs, and simple steps that cut danger a lot.

How anesthesia raises clot risk

When you’re under general anesthesia you’re still for longer, your calf muscles don’t pump blood as they usually do, and blood can pool in the legs. Regional anesthesia (like spinal or epidural) can also change circulation for a short time. Surgery itself triggers inflammation and chemicals that make blood more likely to clot. Add factors like older age, obesity, cancer, smoking, hormone therapy, or recent clots, and the risk climbs.

Type and length of surgery matter. Long surgeries (over two hours), major orthopedic or cancer operations, and procedures with limited post-op mobility are higher risk. Even simple procedures carry some risk if other risk factors are present.

Practical steps to lower your risk

Talk to your anesthesiologist and surgeon early. Tell them if you’ve had a clot, take blood thinners, use birth control, or have a family history of clots. They’ll adjust your plan and may order blood-thinning medicine before or after surgery.

Simple actions make a big difference: get out of bed and walk as soon as it’s safe, wear compression stockings, and use intermittent pneumatic compression devices when offered. If you use anticoagulants (warfarin, apixaban, rivaroxaban), follow the team’s instructions about stopping or restarting them—timing matters.

Hydrate before and after surgery unless directed not to. Smoking increases clot risk and slows recovery, so quitting—even briefly—helps. If you travel a lot before surgery, mention long flights; immobility during travel adds risk.

Know the warning signs. For a DVT: one leg that’s swollen, warm, tender, or red. For a pulmonary embolism: sudden shortness of breath, sharp chest pain, fast heart rate, lightheadedness, or coughing up blood. These are emergencies—call for immediate medical care.

If you’re on blood thinners already, ask how your dose should change around surgery and who will check clotting tests (like INR for warfarin). For new prescriptions, ask about side effects, interactions with other meds or herbal supplements, and what to do if you miss a dose.

If you want a simple checklist before surgery: review your personal and family clot history with the team, list all medicines and supplements, discuss stopping/starting anticoagulants, plan for early mobility, and ask whether compression stockings or injections (low-molecular-weight heparin) are recommended.

Being prepared and speaking up makes anesthesia and surgery safer. If anything feels off after your procedure, trust your instincts and contact your care team right away.