What is a Hematoma? - Definition, Types, Symptoms & Treatment

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  • 0:02 A Look at Hematomas
  • 0:21 Causes of Hematomas
  • 1:17 Types
  • 2:47 Symptoms
  • 3:15 Treatment
  • 4:09 Lesson Summary
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Lesson Transcript
Instructor: Danielle Haak

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

A hematoma forms when blood pools outside of a blood vessel, and they can form anywhere in the body. Learn what causes a hematoma, the different types, possible symptoms, and treatment options.

A Look at Hematomas

What is a hematoma? A hematoma is a collection of blood that has started to clot outside of the blood vessels, and they can form anywhere in the body, including in organs. Hematomas vary in size, location, and severity.

Causes of Hematoma

Simply put, a hematoma is caused by some type of damage to a blood vessel that causes blood to leak out into places it has no business being. Once it pools in this new area, it begins to clot, forming a small lump. Trauma is the most common cause of a hematoma, but this doesn't include just major traumas like car accidents or falling off a building. Trauma can be as simple as a sneeze or cough that is strong enough to damage a blood vessel.

Other causes include aneurysms, medications like blood thinners, diseases like autoimmune disorders or infections, conditions that cause the blood vessels to weaken, high blood pressure, stroke, tumors, or conditions like low blood platelets (which help the blood clot). Finally, hematoma formation may be spontaneous and not linked to any direct trauma.


By far, the most dangerous type of hematoma is that which forms somewhere in the skull. The skull is an enclosed space, so where a hematoma forms and creates pressure, the tissues have nowhere to go. This can cause them to compact and result in brain damage. Let's look at some specific types of hematomas.

Hematomas that can form in or on the head:

  • Epidural hematoma: blood pools in the epidural space (the space between the lining of the brain and the skull)
  • Intracerebral hematoma: blood pools in the brain tissue itself
  • Scalp hematoma: forms outside of the skull and may be felt as a 'bump on the head'
  • Aural or ear hematoma: blood gets trapped between the thin outer skin of the ear and the cartilage
  • Septal hematoma: happens after trauma to the nose and can perforate the septum (tissue that separates the nostrils)

Hematomas that can form on other parts of the body:

  • Orthopedic injuries: occur when broken bones leak blood or damage surrounding tissue
  • Intramuscular hematoma: occurs in a muscle and are usually accompanied by a lot of pain and swelling
  • Subungual hematoma: occurs when the fingers or toes get crunched
  • Subcutaneous hematoma: occurs right under the surface of the skin
  • Intra-abdominal hematoma: can form inside any organ or in the spaces between organs

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