A fat embolism happens when there is fat in the circulatory system, including the veins or arteries. It usually happens after a bone injury, when fat surrounding the bone and muscle gets into broken blood vessels. If a person develops symptoms, it means they have fat embolism syndrome.

Most people with a fat embolism do not experience any symptoms. However, for those who do, the embolism can be life threatening.

Having fat in the bloodstream can resolve itself with time. Sometimes, however, it can lead to a rare but serious condition called fat embolism syndrome. This can cause potentially fatal inflammation, multi-organ dysfunction, and neurological changes.

However, generally, there is a good outcome for this condition. It is especially treatable if doctors catch it early.

Read on to learn about why fat embolisms develop and what to watch out for. This article will also discuss the diagnosis and treatment processes for fat embolisms, as well as how to prevent one from happening.

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An embolism is a blockage due to an object in the bloodstream that is not supposed to be there.

Fat does not usually travel in the bloodstream. However, it can enter it following an injury, especially to the bones.

This happens when fat in the bone marrow or near the bones breaks loose and is able to get into damaged blood vessels. Some surgical procedures on these bones can also cause fat embolism.

Learn about methods of bone fracture repair here.

Fat embolism syndrome

Older research from 2006 estimates as many as 90% of people with serious bone injuries develop a fat embolism. In most, though, there are no symptoms, and the embolism goes away on its own.

However, about 10% of people develop fat embolism syndrome, which means the embolism produces symptoms.

Fractures of the leg and the pelvic bones are more likely than other bone fractures to cause fat embolism. These are long bones, and 3–4% of singular long bone fractures can lead to fat embolism syndrome.

Up to 15% of multiple long bone fractures can cause the condition.

Learn about bone fractures here.

Some risk factors for fat embolism syndrome include:

  • young age
  • having closed fractures
  • having multiple fractures

Some conservative treatment, which does not involve surgery, for long bone fractures can also increase the likelihood of developing fat embolism syndrome. Casts and splints are examples of conservative treatment.

Very rarely, other injuries, illnesses, or procedures may cause a fat embolism, such as:

A pulmonary embolism occurs when a foreign object disrupts the flow of the blood traveling to the lungs. This can affect breathing and circulation and may even be fatal.

A fat embolism can cause a pulmonary embolism. Even when it does not, a person may experience breathing difficulties similar to those accompanying a blockage in the pulmonary artery.

In some cases, a pulmonary embolism may also occur at the same time as a fat embolism. This is because some of the risk factors for the two are similar.

For example, a person who breaks a leg may suffer a fat embolism, then later develop a blood clot in the leg because they do not move around much due to their injury. The leg blood clot can then cause a pulmonary embolism.

Learn more about pulmonary embolism risks after surgery here.

Symptoms of fat embolism syndrome usually appear suddenly rather than slowly. They tend to develop 1–3 days after an injury.

The most important warning signs are:

  • sudden difficulty breathing
  • broken blood vessels that may look like a rash on the chest or face or around the eyes
  • confusion or other neurological symptoms

Some people have other warning signs, including:

Doctors have not established specific diagnostic criteria for a fat embolism. Instead, diagnosis depends on a person’s symptoms and laboratory tests, as well as tests to rule out other issues.

A doctor may monitor blood oxygen, because drops in blood oxygen may indicate a fat embolism.

Some other tests a doctor may recommend include:

Most people with a fat embolism have no symptoms. Among those who do, the outlook is generally good as long as they are able to receive supportive care in a hospital.

For a small number of people, fat embolism syndrome is fatal. Precise estimates of the death rate vary, ranging from 7 to 10%.

Some people with fat embolism syndrome temporarily develop serious complications, such as respiratory distress. Even when people experience these severe symptoms, the condition usually does not cause death.

The following factors could increase the risk of worse outcomes for people with fat embolism syndrome:

  • older age
  • underlying medical conditions
  • the inability of a person’s organs to function under stress

There is no specific treatment that can reverse or cure a fat embolism.

Instead, doctors provide supportive care to ensure a person can breathe until the embolism clears. A person may need to be on oxygen and, in some cases, may need to use a ventilator.

A doctor may also give a person the drug albumin or electrolytes to bind to fat and help maintain normal blood volume.

There is no evidence that steroids, anticoagulants, or similar drugs can cure or treat a fat embolism.

There is no specific treatment for a fat embolism. That is why prevention can reduce the length of hospital stays and lower the risk of complications and death.

Some preventative strategies include:

  • blood oxygen monitoring to help detect a fat embolism early, before symptoms become severe
  • administering early, aggressive treatment for long bone fractures
  • giving fluids to people who experience serious fractures
  • giving the drug methylprednisolone to people at a higher risk of developing fat embolisms

A fat embolism is a common complication of severe bone breaks.

Most people recover, and they never even notice symptoms. For those who do, prompt medical care can improve the outcome.

People who fall or suffer other serious injuries that might break the bones should seek emergency medical treatment to reduce the risk of a fat embolism.