Leg Pain: Is It a blood clot, cramp, or pulled muscle?

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Leg pain is something we often shrug off as little or nothing to worry about. Those who participate regularly in sports and physical activities might pick up knocks, bruises, and small or nagging injuries, or get a case of leg cramp after rushing through a warm-up. For contact sports, in particular, discomfort, to an extent, comes with the territory.

But on rarer occasions, leg pain and swelling can be an indication of something exponentially more serious.

National Thrombosis Week takes place each year in May. Run by the charity Thrombosis UK, the intended outcomes of the scheme are to help promote understanding and awareness of thrombosis, supply those affected by the condition with the insight and support they require, and ultimately lessen the impact of thrombosis on public health.

To mark the occasion and do our bit, in this article we’ll be discussing deep vein thrombosis in more detail; more specifically, what does DVT look and feel like and how do you tell it apart from cramp or a muscle injury?

  • What is a blood clot?
  • When is a blood clot dangerous?
  • Are DVTs a serious health risk? 
  • Signs and symptoms of a blood clot
  • How is a blood clot different from a leg cramp? 
  • How a blood clot is diagnosed
  • The causes of blood clots
  • Treatment for blood clots

What is a blood clot?

Clotting is a crucial function of the body. Whenever we sustain a cut or laceration, blood needs to be able to form a solid congealed lump (such as a scab) in order to prevent further blood loss (also known as hemorrhaging).

When the skin breaks or a blood vessel breaks, chemicals in the body signal platelets into action. Platelets adhere to the cell surfaces around the affected region and to each other, becoming solid to effectively stop the gap so that no more blood escapes. Platelets then emit a chemical transmitter which draws in more platelets, so that the stop can become larger.

Clotting proteins also communicate with these chemicals and another reaction occurs, resulting in the formation of fibrin lines, an element that becomes intertwined with platelets to develop a trapping layer for other platelets (causing the clot to grow even more).

Once the clot has reached a sufficient size, balancing proteins are released which stop it from growing any further. After the tissue in the affected area has healed, the lines of fibrin disintegrate, and the blood refills platelets stores.

How does a blood clot become harmful?

However, the above instance isn’t the only one in which clots can form.

Sometimes when poor blood flow leads to the slowing down of blood or an accumulation of it in one area (such as in an artery or a vein), platelets in the blood will come into contact with each other and start to knit together. This can trigger a clot, known also as a thrombosis.

Those with high cholesterol are at risk of harmful clots too, as ruptures in cholesterol deposits in the arteries can also initiate the clotting process. If you don’t know your cholesterol level, you can find out by using a home cholesterol test kit. The rapid result can let you know if you need to take action. 

When do blood clots pose a serious health risk?

A blood clot in a leg (deep vein thrombosis or DVT) becomes potentially life-threatening when it moves or a piece of it breaks off and travels through the bloodstream to the arteries near the heart and lungs.

This is referred to as a pulmonary embolism (PE). Roughly ten percent of those with DVT will go on to develop this condition, which can happen immediately, or sometime after. Heart failure, pulmonary hypertension, and breathing problems are some of the issues that can result from PE, so noticing blood clots and taking action as soon as possible is vital.

What are the signs of a blood clot in the leg?

One aspect of a blood clot in a leg which makes a diagnosis troublesome is that it doesn’t always cause symptoms; it is thought that only fifty percent of cases will show visible signs.

Symptoms of a blood clot in the leg: 

In cases where symptoms are present, those with DVT in a leg may notice:

  • skin that is warm to the touch in the affected area
  • swelling or pain in the affected calf muscle or area. The pain will usually get worse over time and does not come and go, like the feeling of a pulled muscle might
  • a red or raw tender area of skin, often below the back of the knee
  • veins that feel hard or swollen when you touch them

The above will usually occur in just one leg, but it is possible to get DVT in both legs at the same time. These symptoms can also occur in the stomach area or arm if that is where the clot is located.

A pulmonary embolism, which untreated DVT can lead to, may produce:

  • breathlessness
  • stabbing chest pain
  • bloody cough
  • and an increased heart rate.

How is a blood clot different from a pulled muscle or cramp?

While a blood clot will require medical attention, a bout of cramps often won’t. Furthermore, a pulled muscle will require care to alleviate pain and symptoms, but it will often not be considered a medical emergency (unless there has been suspected joint damage, a tissue tear, or a break).

It can nevertheless be easy to confuse a blood clot with a cramp or a pulled muscle, as the symptoms can be fairly similar.

There are however a few ways in which they might potentially differ:

  • the cramp will often occur in both legs or at least in more than one area; as opposed to a blood clot, symptoms of which will most typically be concentrated in one leg, often the calf muscle
  • cramp and pulled muscles will cause pain but not necessarily hot skin or redness in the affected area
  • whereas cramps can be ‘walked off’ and thus go away, pain caused by a blood clot is more likely to persist
  • bending the foot at the ankle, so that the toes point upwards, will cause or intensify pain in the calf muscle if a blood clot is present.

Those who are unsure should certainly have their symptoms examined by a doctor to rule out DVT as soon as possible.

How do you know if you have a blood clot?

For a diagnosis to be made a doctor will perform a physical examination. If they suspect a blood clot is present, they may refer a patient for an ultrasound scan for confirmation.

What causes blood clots in the leg?

With blood clots, there isn’t always a definitive cause.

Certain health factors do however increase an individual’s risk of a blood clot developing.

These include:

  • smoking
  • being overweight
  • being dehydrated
  • and being over the age of 60.

As mentioned above, remaining immobile for long periods may cause blood to pool in one place and encourage platelets to form a clot. This means that:

  • those traveling on long-haul flights
  • and those staying in the hospital

can be more susceptible.

Some medical conditions can cause the blood to clot more readily in some patients. These include:

  • thrombophilia
  • heart and lung diseases
  • hepatitis
  • Hughes syndrome
  • and cancer.

Pregnant women are also more at risk. During pregnancy, the body prepares to limit the amount of blood it expects to lose during childbirth and is much quicker to initiate the clotting process as a result.

Estrogen contained in combined hormonal birth control and menopause treatments can increase the likelihood of clotting too.

How is DVT treated?

Most cases of DVT can be treated with anticoagulant medicines, which are known more widely as ‘blood-thinners’.

This term isn’t technically correct: anticoagulants don’t reduce the consistency of the blood. However, these treatments do alter the chemical composition of blood so that it does not clot quite so readily.

This helps to reduce the likelihood of subsequent clots and stops those already present from becoming larger.

Typically, heparin will be issued upon positive diagnosis of DVT as it begins to function right away and will be applied by a doctor or nurse via injection. Those undertaking this method of treatment will usually be admitted to the hospital and have their condition kept under surveillance.

Following this, warfarin tablets may be given as a maintenance treatment. The hospital will undertake regular blood tests at first to determine the appropriate dose.

Other measures, such as compression stockings and elevating the leg while sitting, are often advised in addition to the above medications, as they can help to reduce the chances of further episodes.

If you suspect you may have a blood clot, you should contact your doctor or your nearest hospital immediately. If you have persistent calf pain and a DVT has been ruled out then you may wish to seek medical attention for treatment such as physiotherapy.

You can find out more about National Thrombosis Week over at Thrombosis UK.

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Tom Perry, M.D., attended Tulane University and graduated Magna Cum Laude with a B.S. degree in Parasitology. He received his M.D. degree in 1983 from the University of Virginia School of Medicine, where he gained extensive research experience, including studies conducted through the National Institutes of Health.