Blood clots

Updated on: August 18, 2014

In the normal individual, there is a delicate balance in the blood system governing formation of blood clots. In simplicity, blood clots are a combination of some blood factors which in real life look like "jelly". Blood clots are useful to stop bleeding and help healing. The body has mechanisms to dissolve the clots once they have provided their function. Sometimes these blood clots persist and can cause problems.

Where can blood clots occur?

Blood clots can occur in both arteries and veins. Blood clots can occur in any artery or vein. When it comes to the veins, only blood clots in the deeper veins are of medical significance. Blood clots in the superficial veins (varicose veins) are of little medical significance.

What are arteries?

Arteries are muscular blood vessels which supply oxygenated blood to the body. The largest of the artery is the aorta and it comes off the heart. Along its way, it gives off many branches, some of which go to the brain, arms, kidney, spinal cord, legs, groin, etc.

Can clots occur in arteries?

Yes, blood clots can and do occur in arteries. Because arteries supply oxygen to the body, blood clots can block the artery and hence disrupt oxygenated blood to the tissues. This is what happens in a heart attack. Blood clots in the arteries can block blood supply anywhere in the body and often occurs in the brain, legs and kidneys. In most cases, urgent treatment is required to remove the blood clot from the artery.

What are veins?

Veins are thin walled vessels which play a role in removing all the deoxygenated blood from the tissues and taking it back to the lungs for oxygenation. They are numerous veins all over the body; the largest vein is called the inferior vena cava.

Can blood clots occur in veins?

Most definitely, clots are far more common in veins than arteries. When clots occur in veins they have a tendency to break off and move to the lungs where they can compromise breathing. Clots can occur in both the arm and leg veins.

Where do blood clots in veins usually occur?

The majority of blood clots in the veins occur in the legs but they can occur in any veins in the body.

What happens when blood clots move to the lungs?

The lungs are important for gas exchange. When blood clots move into the lungs, they can block the airways and prevent this gas exchange. If the clots are large, one will have difficulty breathing and deaths are not uncommon.

Are blood clots in the veins common?

In the United States, about 2 million people per year develop blood clots. Most of them are aged 40 years or older. Statistics reveal that at least 200,000 patients die each year from blood clots in their lung.

How do I know if I have blood clots?

It depends where the blood clot has formed. In most cases, it is the legs, especially the calf area. You may have some of the following symptoms:

a. heaviness of the leg

b. tenderness in the calf area

c. swelling in the calf area

d. warmth near the calf

e. at least 30% will not have any symptoms

What causes blood clots in the veins?

There are many reasons why blood clots can form in the veins. These include

- Prolonged immobility (after surgery)

- Long airplane ride

- Taking the birth control pill

- Trauma or fractures of the legs

- Injury to the veins

- Cancer

- Stroke- which has caused one to be bed ridden

- After any surgery- especially hip and knee

- Obesity

- Congestive heart failure

- Pregnancy or just after delivery

- Inherited blood disorders

- Prior blood clot –there is increased chance of a second clot if one has had a previous blood clot

Are blood clots dangerous?

Most definitely. Any time you have one of the above symptoms; one should go and see a doctor. Blood clots in the veins have a high tendency to break off and migrate to the lungs where they can cause serious problem's including death.

How can blood clots in veins be detected?

Your physician will first examine you and order the most appropriate tests. The first test to detect blood clots in all cases is:

Doppler ultrasound: This painless test takes a few minutes and can easily detect the presence of blood clots in the arm and leg veins. However, if blood clots are located in the chest, abdomen or pelvis, Ultrasound is not good enough.

MRI: This non invasive test is also excellent for evaluating the presence of blood clots. The test does not use radiation but is slightly more expensive. It is useful for detection of blood clots almost anywhere in the body, but is not the first test of choice.

Venogram: In the old days venogram was used to look for blood clots. However this test is rarely used to day because of the availability of US and MRI. Venogram requires the use of a dye and radiation.

CT scan: The newer CT scans can easily identify the presence of clots in the lungs. However, CT scans are not routinely used to detect for blood clots as the initial test. CT scan requires exposure to radiation and use of an iodinated dye.

What is the treatment of a blood clot?

If a blood clot is found, you will require admission to the hospital for at least 4-7 days. Following some blood work, you will be started on:

Heparin: This is a blood thinner which is given intravenously. It does not dissolve the clot but helps to stabilize the clot so that it does not move. After a few days, you will be started on an oral medication called warfarin and then discharged home. Anyone who receives warfarin needs their blood assessed on a weekly to monthly basis to ensure that the blood thinning is adequate.

How long do I need to take a blood thinner?

For a first time blood clot, you will need to take warfarin for at least 6-9 months. Those with recurrent blood clots will require warfarin for an indefinite time.

Are there any other medications one can take for blood clots?

Yes, the newer medications are called low molecular weight heparins (LMWH). These medications do not require monitoring and can be taken at home. Unfortunately they need to be injected daily and are more expensive.

Is there a risk from taking these medications?

Yes, all blood thinning medication can cause bleeding. Thus one should avoid activities that can lead to trauma to the body, otherwise severe bleeding can occur.

Are there any medications to dissolve the clot instantly?

Yes, there are medications (thrombolytics) which can rapidly dissolve the clots. However, there are specific indications for the use of these medications and they all carry a higher risk of complications. Their use is only limited to hospital patients.

Is surgery ever used to treat blood clots?

Yes, in the rare case surgery (thrombectomy/embolectomy) is sometimes used in the treatment of blood clots. However, this is done for life or limb threatening cases only. There is no role for surgery in the routine treatment of blood clots.

What happens if I am unable to tolerate a blood thinning medication?

There are devices (filters) which can be placed in the body to prevent the blood clot from moving to the lung. These devices have an umbrella like appearance and do not dissolve the clot but prevent it from going to the lungs. Filters are more commonly used in individuals who can not take blood thinners. They cost as much as a BMW and so their use is limited and they are only a temporary solution.

Can blood clots be removed from the lungs?

The first choice for treating blood clots is medication. However, in some individuals the blood clot may have completely blocked the lungs and cause severe breathing problems. In such cases, surgery (pulmonary thromboembolectomy) may be done to remove the clot from the lungs. This is life saving surgery and is of extremely high risk

How can I prevent blood clots?

The best methods of preventing blood clots include:

- Being active, walking on a daily basis

- If flying or driving a long distance, walk around every few hours

- Wear compression stockings

- Lose weight

- Avoid prolonged standing

- Avoid the birth control pill

Is there any home treatment for blood clots?

Yes, after you have been started on a blood thinner, one can relieve the symptoms by:

- elevating the leg which will decrease the swelling and pain

- Avoid standing for long periods

- One can apply a warm compress if there is a blood clot around the legs

Final advice

For those with a blood clot and taking blood thinning medications, one should wear a medical bracelet to alert all health care professionals.

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