A hematoma is a collection of blood under the surface of the skin. Most often referred to as a bruise, hematomas are generally considered safe when they appear on the skin, referred to medically as a subdermal hematoma. Others forms of hematoma are far more dangerous including the subdural, epidural and subchorionic hematoma.

Subdural hematoma

When a subdural hematoma occurs, blood collects on the outer brain surface. Most often, a subdural hematoma results from an injury to the head. If the blow to the head is strong enough an acute subdural hematoma may result leading to a large bleed in the brain and subsequent death, if the condition is not treated very quickly. If only a mild injury to the head was suffered, a small but persistent bleed can result, especially in elderly patients. This bleed is often referred to as a chronic subdural hematoma.

Characteristics of a subdural hematoma include bleeding between the dura mater and arachnoid, a headache that gradually increases in intensity, confusion and an area of crescent shape discoloration on a CT scan.

Epidural hematoma

The epidural hematoma results from an injury to the brain, typically a head injury. The blood collects between the dura mater and the skull. The subdural hematoma is a type of epidural hematoma. Bleeding is fast with a peak blood loss of up to 75 cubic centimeters in just six hours. The most common symptom of an epidural hematoma is a severe headache.

Characteristics of an epidural hematoma include bleeding between the dura mater and skull, severe headache and unconsciousness.

Subchorionic hematoma

The subchorionic hematoma is thought to be linked to the implantation of the egg in the uterus. When the egg implants, if a small tear occurs a bleed can result. The bleed may cause bleeding from the vagina early in pregnancy causing concern which leads to an ultrasound. On the ultrasound, the bleed will look like a dark spot, similar to how the placenta looks. A subchorionic hematoma is located between the placenta and the uterus, so it could be misdiagnosed as a twin by the untrained eye. Most often the bleed will continue with a resolution by the 20th week of the pregnancy. Either the hematoma will simply stop bleeding or the uterus will absorb the hematoma.

Characteristics of a subchorionic hematoma include vaginal bleeding early in pregnancy. There are no known causes of a subchorionic hematoma and there is nothing that can be done to prevent it from presenting. Unless the bleed is severe or large, most pregnant women will not have to worry about it. There is no treatment for the hematoma.