What are blood clots?
Blood clots are clumps of blood that form in veins or arteries. They occur when the blood thickens and clumps together. Blood clots in the legs are also known as deep vein thrombosis (DVT). DVT usually occurs in the major veins of the lower legs, thighs or pelvis.
A blood clot in the leg can be dangerous if it breaks off and travels through the bloodstream to the lungs. This is known as pulmonary embolism (PE), a medical emergency. Blood clots in the legs don’t always cause symptoms. But it’s important to recognize DVT symptoms and get prompt medical attention.
What causes blood clots in the legs?
A DVT blood clot usually forms in the calf veins. Things that can increase your risk of developing DVT include:
– Being immobile or inactive. Blood pools in the veins of your leg if you’re unable to move around for long periods. This pooling increases the risk of clot formation.
– Injury to a vein. Major injuries cause trauma to the leg veins, leading to swelling and clot formation. Minor injuries like cuts and bruises can also increase DVT risk.
– Pregnancy. Pregnancy increases pressure in the veins in the pelvis and legs. Clotting factors in the blood also increase. These changes make pregnant women more prone to clotting.
– Medical conditions like heart disease. Some medical problems increase clotting factors in the blood.
– Birth control pills or hormone replacement therapy. The extra estrogen increases clotting factors.
– Cancer and cancer treatment. Cancer cells can release substances into the blood that cause blood to clot. Chemotherapy, hormone therapy and immobilization during cancer treatment increase DVT risk.
– Smoking. This damages the blood vessel lining, making clot formation more likely.
– Being overweight or obese. This puts extra pressure on veins.
– Older age. The blood vessels lose elasticity and become damaged more easily over time.
– Personal or family history of DVT or genetic conditions like Factor V Leiden that increase clotting risk.
Signs and symptoms of a blood clot in the leg
Some common signs and symptoms of a DVT blood clot in the leg are:
– Pain in the leg. This is the most common symptom. The pain often starts in the calf and can feel like cramping or soreness. Pain worsens with walking and standing.
– Tenderness in the leg. The area around the clotted vein may feel warm, firm and tender when touched.
– Swelling in the foot, ankle, leg or thigh.
– Red or discolored skin on the leg. The skin over the vein with clot can look red or purplish.
– Leg warm to touch. The skin over the affected vein may feel warm when touched.
– Leg veins look more prominent. Veins can appear swollen and enlarged.
– Leg fatigue. The legs may feel heavy, tired or weak.
– Night cramps in the legs that may be relived by dangling the legs over the side of the bed or walking.
Some people with DVT have no symptoms at all. In these cases, the clot may only be discovered by medical imaging.
Risk factors for blood clots in the legs
Anything that slows down normal blood flow and circulation increases the risk of DVT. Health conditions and factors that can increase your risk of DVT include:
Inactivity
Being immobile or inactive for long periods of time can cause blood to pool and clot. This risk increases with:
– Bed rest following surgery or severe illness
– Sitting for long periods of time, like during long car trips or flights
– Wearing a cast on a broken bone that immobilizes the leg
Pregnancy
Pregnancy causes the following changes that increase risk of blood clots:
– Blood vessels widen and blood pools in the legs.
– Increased clotting factors in the blood
– Pressure of the enlarged uterus on pelvic veins
The risk of pregnancy-related DVT is highest in the weeks right after giving birth.
Birth control pills
Birth control pills and hormone replacement therapy contain estrogen. This hormone increases certain clotting factors in the blood. The risk of clots is highest in the first year of taking these.
Cancer
Cancer and cancer treatment increases clotting. Risk factors include:
– Cancer itself – Cancer cells can stimulate blood coagulation
– Chemotherapy – Reduces platelets and makes blood more likely to abnormally clot
– Hormone therapy – Increases clotting proteins
– Central vein catheter – Can damage vessel walls
Heart diseases
Certain heart conditions also increase DVT risk. These include:
– Atrial fibrillation – Causes blood to pool in heart chambers and form clots
– Heart attack or heart failure – Weakens the heart and alters blood flow
– Heart valve problems – Lead to blood turbulence and pooling
– Heart infection – Causes inflammation and changes in blood flow
Family history and genetic factors
Some genetic conditions can increase your risk of inappropriate blood clotting. These include:
– Factor V Leiden – Makes blood more prone to clotting
– Prothrombin G20210A – Increases levels of clotting factors
– Antiphospholipid syndrome – Causes excessive clotting
A family or personal history of DVT or PE also raises your risk of a recurrent clot.
Age
The risk of blood clots increases with age. This is because:
– Veins lose elasticity over time
– Blood flow can slow with aging
– More medical conditions that affect clotting risk arise later in life
After age 60, DVT risk doubles with each passing decade.
Obesity
Being overweight or obese can compress leg veins and slow blood flow, leading to clot formation.
Smoking
Smoking damages blood vessels, impairing blood flow. Smokers have a risk 2-4 times greater than nonsmokers.
Recent surgery
Undergoing knee or hip replacement, or surgery that removes part of the bowel or prostate gland increases DVT risk. Being immobile during and after surgery is partly responsible.
| Risk factor | How it increases risk |
|---|---|
| Inactivity, bed rest | Blood pools in the veins of the legs |
| Pregnancy | Pressure on veins from the enlarging uterus |
| Birth control pills or HRT | Increases clotting factors |
| Cancer | Cancer cells can increase clotting |
| Heart disease | Alters blood flow |
| Family history | Inherited clotting disorders |
| Older age | Veins stiffen and blood flow slows |
| Obesity | Compresses leg veins |
| Smoking | Damages blood vessels |
| Recent surgery | Immobility during and after surgery |
When to see a doctor
See your doctor right away if you develop any symptoms of a possible blood clot in your leg, especially if they are severe or come on suddenly. Prompt treatment of DVT can help prevent complications like pulmonary embolism.
Get emergency help if you have signs of a PE like:
– Sudden shortness of breath
– Sharp chest pain that worsens with deep breathing
– Rapid breathing
– Coughing up blood
– Excessive sweating
– Lightheadedness or fainting
Diagnosing blood clots in legs
To diagnose DVT, your doctor will ask about your symptoms and medical history. A physical exam can help find signs of a clot like swelling or warmth in the leg.
There are two main imaging tests used to help confirm a DVT:
Duplex ultrasonography
This uses sound waves to look for clots in the veins of the legs. It can find the location and size of the blood clot. This test is painless and doesn’t expose you to radiation.
Contrast venography
This involves injecting a contrast dye into a vein in the foot. X-rays are taken to look for blocked areas or clots in the blood vessels. Venography is more accurate but can cause discomfort and reactions to the dye.
Other tests that may be done include:
– Blood test called D-dimer – A high level indicates increased clotting somewhere in the body.
– CT scan – This provides pictures of the blood vessels throughout the body.
– MRI scan – This uses magnets and radio waves to create images of the veins in the legs.
Treating blood clots
Treatment focuses on preventing the blood clot from getting larger and preventing any new clots from forming. Steps include:
Anticoagulant medications
Medicines like heparin, warfarin (Coumadin), apixaban (Eliquis), dabigatran (Pradaxa) and rivaroxaban (Xarelto) are used. These prevent further growth of the clot. They don’t break up the existing clot but allow it to slowly dissolve.
Compression stockings
Wearing medical compression stockings promotes blood flow in the legs. They provide gradual compression around the ankle and up the leg. This compression helps blood circulate and prevents pooling.
Getting up and moving
Moving around as soon as possible after diagnosis prevents blood from pooling in the legs. Your doctor will recommend when it’s safe to walk and resume activity after a blood clot.
Elevating the leg
Resting with your leg raised slightly higher than your heart level directs blood flow back to the heart. This helps swelling and pain get better.
Thrombolytic therapy
For severe clots, you may get strong clot-busting medicines through an IV line. These work to dissolve the clot quickly. Thrombolytics carry a risk of major bleeding.
Vena cava filter
If anticoagulant medicines can’t be used, a filter may be placed in the large abdominal vein (vena cava) to catch any clots breaking off from the leg and heading to the lung.
Surgery
A surgical procedure rarely used for DVT is thromboembolectomy. It involves making an incision into the vein to remove the blood clot. This is done when anticoagulation fails to prevent advancement of the clot.
Complications
Some potential complications of untreated DVT include:
– Pulmonary embolism – A life-threatening condition where part of the clot breaks off and travels to the lungs, blocking blood flow. Signs include chest pain, cough, shortness of breath and irregular heartbeat.
– Post-thrombotic syndrome – Damage to the venous valves from the blood clot results in chronic leg pain, swelling, varicose veins and skin ulceration.
– Recurrent leg clots – Once you’ve had a DVT, there’s an increased risk of another occurring.
Recovery and prevention
With early treatment, most people recover completely from DVT. To prevent blood clots from forming again:
– Take anticoagulants as prescribed.
– Don’t stop medications without your doctor’s approval.
– Follow up regularly with your doctor.
– Wear compression stockings.
– Maintain an active lifestyle with regular exercise.
– Maintain a healthy weight.
– Stay hydrated by drinking plenty of fluids.
– Avoid long periods of standing or sitting immobile.
– Elevate legs when sitting or sleeping.
– Don’t smoke.
Conclusion
Blood clots in the legs are a serious concern. Know the risk factors and key symptoms like leg pain, swelling and warmth. See a doctor promptly if you suspect a clot. With early diagnosis and proper treatment, you can recover and prevent future episodes of DVT. Maintaining overall vascular health helps minimize the risks.