Hematoma
Overview
 
A hematoma, or haematoma, is a localized collection of blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 outside the blood vessels, usually in liquid form within the tissue. This distinguishes it from an ecchymosis
Ecchymosis
An ecchymosis is the medical term for a subcutaneous purpura larger than 1 centimeter or a hematoma, commonly called a bruise. It can be located in the skin or in a mucous membrane.-Presentation:...

, which is the spread of blood under the skin in a thin layer, commonly called a bruise
Bruise
A bruise, also called a contusion, is a type of relatively minor hematoma of tissue in which capillaries and sometimes venules are damaged by trauma, allowing blood to seep into the surrounding interstitial tissues. Bruises can involve capillaries at the level of skin, subcutaneous tissue, muscle,...

. Internal bleeding is generally considered to be a spreading of blood within the abdomen or skull, not within muscle.

It is not to be confused with hemangioma
Hemangioma
A hemangioma of infancy is a benign self-involuting tumor of endothelial cells, the cells that line blood vessels. It usually appears during the first weeks of life and sometimes resolves by age 10. In more severe case hemangioma may have permanency, if not treated by a physician...

 which is an abnormal build up of blood vessels in the skin or internal organs.
The word "hematoma" came into usage around 1850.
Encyclopedia
A hematoma, or haematoma, is a localized collection of blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 outside the blood vessels, usually in liquid form within the tissue. This distinguishes it from an ecchymosis
Ecchymosis
An ecchymosis is the medical term for a subcutaneous purpura larger than 1 centimeter or a hematoma, commonly called a bruise. It can be located in the skin or in a mucous membrane.-Presentation:...

, which is the spread of blood under the skin in a thin layer, commonly called a bruise
Bruise
A bruise, also called a contusion, is a type of relatively minor hematoma of tissue in which capillaries and sometimes venules are damaged by trauma, allowing blood to seep into the surrounding interstitial tissues. Bruises can involve capillaries at the level of skin, subcutaneous tissue, muscle,...

. Internal bleeding is generally considered to be a spreading of blood within the abdomen or skull, not within muscle.

It is not to be confused with hemangioma
Hemangioma
A hemangioma of infancy is a benign self-involuting tumor of endothelial cells, the cells that line blood vessels. It usually appears during the first weeks of life and sometimes resolves by age 10. In more severe case hemangioma may have permanency, if not treated by a physician...

 which is an abnormal build up of blood vessels in the skin or internal organs.

Presentation

The word "hematoma" came into usage around 1850. The word derives from the Greek roots "hemat-" (blood) and -oma, from soma, meaning body = a body of blood. Another etymological derivation would be from "haemat-" and "-oma" = "-ing", thus simply "bleeding".

Hematomas can occur within a muscle. Some hematomas form into hard masses under the surface of the skin. This is caused by the limitation of the blood to a subcutaneous or intramuscular tissue space isolated by fascial planes. This is a key anatomical feature that prevents such injuries from causing massive blood loss. In most cases the sac of blood or hematoma eventually dissolves; however, in some cases they may continue to grow or show no change. If the sac of blood does not disappear, then it may need to be surgically removed. Hematomas can occur when heparin
Heparin
Heparin , also known as unfractionated heparin, a highly sulfated glycosaminoglycan, is widely used as an injectable anticoagulant, and has the highest negative charge density of any known biological molecule...

 is given via an intramuscular route; to avoid this, heparin must be given intravenously or subcutaneously.

The slow process of reabsorption of hematomas can allow the broken down blood cells and hemoglobin pigment to 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

  • Subdermal hematoma (under the skin
    Skin
    -Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...

    )
  • Head/brain:
    • Subgaleal hematoma – between the galea aponeurosis and periosteum
      Periosteum
      Periosteum is a membrane that lines the outer surface of all bones, except at the joints of long bones. Endosteum lines the inner surface of all bones....

    • Cephalohematoma – between the periosteum
      Periosteum
      Periosteum is a membrane that lines the outer surface of all bones, except at the joints of long bones. Endosteum lines the inner surface of all bones....

       and skull
      Skull
      The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...

      . Commonly caused by vacuum delivery and vertex delivery.
    • Epidural hematoma
      Epidural hematoma
      Epidural or extradural hematoma is a type of traumatic brain injury in which a buildup of blood occurs between the dura mater and the skull. The dura mater also covers the spine, so epidural bleeds may also occur in the spinal column...

       – between the skull
      Skull
      The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...

       and dura mater
      Dura mater
      The dura mater , or dura, is the outermost of the three layers of the meninges surrounding the brain and spinal cord. It is derived from Mesoderm. The other two meningeal layers are the pia mater and the arachnoid mater. The dura surrounds the brain and the spinal cord and is responsible for...

    • Subdural hematoma
      Subdural hematoma
      A subdural hematoma or subdural haematoma , also known as a subdural haemorrhage , is a type of haematoma, a form of traumatic brain injury. Blood gathers within the outermost meningeal layer, between the dura mater, which adheres to the skull, and the arachnoid mater, which envelops the brain...

       – between the dura mater
      Dura mater
      The dura mater , or dura, is the outermost of the three layers of the meninges surrounding the brain and spinal cord. It is derived from Mesoderm. The other two meningeal layers are the pia mater and the arachnoid mater. The dura surrounds the brain and the spinal cord and is responsible for...

       and arachnoid mater
      Arachnoid mater
      The arachnoid mater, literally from Latin "spider -like mother", is one of the three meninges, the membranes that cover the brain and spinal cord...

    • Subarachnoid hematoma – between the arachnoid mater
      Arachnoid mater
      The arachnoid mater, literally from Latin "spider -like mother", is one of the three meninges, the membranes that cover the brain and spinal cord...

       and pia mater
      Pia mater
      Pia mater often referred to as simply the pia, is the delicate innermost layer of the meninges, the membranes surrounding the brain and spinal cord. The word finds its roots in Latin, meaning literally "tender mother." The other two meningeal membranes are the dura mater and the arachnoid mater....

       (the subarachnoid space
      Subarachnoid space
      In the central nervous system, the subarachnoid cavity is the interval between the arachnoid membrane and pia mater....

      )
    • Othematoma – between the skin and the layers of cartilage of the ear

  • Perichondral hematoma
    Cauliflower ear
    Cauliflower ear is a condition that occurs when the external portion of the ear suffers a blow, blood clot or other collection of fluid under the perichondrium...

     (ear
    Ear
    The ear is the organ that detects sound. It not only receives sound, but also aids in balance and body position. The ear is part of the auditory system....

    )
  • Perianal hematoma
    Perianal hematoma
    A perianal hematoma is a type of hematoma located in, or on the border of the anus. It can be misdiagnosed as a hemorrhoid, but is sometimes referred to as an external hemorrhoid.-Causes:...

     (anus
    Anus
    The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest,...

    )
  • Subungual hematoma
    Subungual hematoma
    A subungual hematoma is a collection of blood underneath a toenail or fingernail . It can be extremely painful for an injury of its size although otherwise it is not a serious medical condition...

     (nail)

Degrees

  • Petechiae – small pinpoint hematomas less than 3 mm in diameter
  • Purpura
    Purpura
    Purpura is the appearance of red or purple discolorations on the skin that do not blanch on applying pressure. They are caused by bleeding underneath the skin...

     (purple) – a bruise about 1 cm in diameter, generally round in shape
  • Ecchymosis
    Ecchymosis
    An ecchymosis is the medical term for a subcutaneous purpura larger than 1 centimeter or a hematoma, commonly called a bruise. It can be located in the skin or in a mucous membrane.-Presentation:...

    – subcutaneous extravasation of blood in a thin layer under the skin, ie bruising or "black and blue".
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