Fat Embolism: Definition, Causes, Symptoms & Treatment

Instructor: Danielle Haak

Danielle has a PhD in Natural Resource Sciences and a MSc in Biological Sciences

A fat embolism is a glob of fat that gets into the bloodstream. It is problematic when the glob is too large to pass through a blood vessel, causing it to get stuck. Read this lesson to learn how this happens and what to do if it does.

What is a Fat Embolism?

Let's back up and start with the basics. First off, an embolus is an intravascular mass that gets stuck when traveling through the bloodstream and causes a blockage. A fat embolism is an embolus made up of fatty acids. So basically, it's a glob of fat that gets into the bloodstream and lodged in a blood vessel. This condition is hard to diagnose and is common following a major injury or trauma. Let's look at what causes a fat embolism with a little more detail.

The clear circles in the middle of this image are fatty acids in the blood.
fat embolism

Causes of Fat Embolisms

The most common cause of a fat embolism is a broken long bone, like the femur. Why? Well, when a bone breaks, fat from the bone marrow can seep out into the bloodstream. In fact, most broken bones cause some fat to enter the blood stream, but not all of this fat causes a blockage; closed fractures (the bone doesn't break through the skin) cause more embolisms than open fractures.

Other causes include major surgery (like hip and knee replacements), pancreatitis, burns, child birth, bone marrow biopsies, soft tissue damage, and non-traumatic procedures or conditions like liposuction, fatty liver, or sickle cell disease. Anything that introduces fat into the bloodstream can result in a fat embolism if the fat reaches a blood vessel it can't fit through.

Symptoms of Fat Embolisms

The time frame for an embolism is anywhere from 12-72 hours after the trauma, and the symptoms vary based on where the blockage occurs. The most problematic embolisms occur in the brain, lungs, or skin, and fat embolisms are fatal approximately 10-20% of the time.

Possible symptoms can occur throughout the body, and sometimes, fat embolisms are difficult to diagnose. Typically, either two of three major symptoms must be present or one major symptom and at least four minor symptoms.

These major symptoms include:

  • Lung impairment
  • Cerebral (brain) impairment
  • Petechial rash (red spots on the skin that don't turn white when pressed)

Minor symptoms include:

  • Rapid breathing
  • Jaundice
  • Fever
  • Trouble breathing
  • Low oxygen concentration in blood
  • Confusion
  • Kidney problems
  • Anemia
  • Thrombocytopenia (low platelet count)

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