Hematoma

A hematoma, or haematoma, is a collection of blood, generally the result of hemorrhage, or, more specifically, internal bleeding. Hematomas exist as bruises (ecchymoses), but can also develop in organs. Some hematomas form into a welt-like formation that is hard to the touch, which is a sac of blood that the body creates to keep internal bleeding to a minimum. In most cases the sac of blood eventually disolves, however in some cases they may continue to grow or show no change. If the sac of blood does not disappear it may need to be surgically removed.

It is not to be confused with hemangioma which is an abnormal build up of blood vessels in the skin or internal organs.

Hematomas can gradually migrate, as the effused cells and pigment move in the connective tissue. For example, a patient who injures the base of his thumb might cause a hematoma which will slowly move all through the finger within a week. Gravity is the main determinant of this process.

Hematomas on articulations can reduce mobility of a member and present roughly the same symptoms as a  fracture.

Types

 * Head/brain:
 * Subgaleal hematoma &mdash; between the galea aponeurosis & periosteum
 * Cephalhematoma &mdash; between the periosteum & skull
 * Epidural hematoma &mdash; between the skull & dura mater
 * Subdural hematoma &mdash; between the dura mater & arachnoid mater
 * Subarachnoid hematoma &mdash; between the arachnoid mater and pia mater (the subarachnoid space)
 * Perichondral hematoma (ear)

Degrees of hematoma

 * hematoma - bruise
 * petechiae - small pinpoint hematomas less than 3 mm in diameter
 * purpura - (purple) a bruise about 1 cm in diameter, generally round in shape
 * ecchymoses or eccymosis - hematoma greater than 3 mm