Hematomas are often described based upon their location.

Epidural hematomas occur because of trauma, often to the temple, where the middle meningeal artery is located. Bleeding accumulates in the epidural space, outside the 'dura' which is the lining of the brain. Because of the way the dura is attached to the skull, small hematomas can cause significant pressure and brain injury.

Subdural hematomas also occur because of trauma but the injury is usually to the veins in the brain. This causes a slower leak of blood, which enters the 'subdural' space below the dura. Bleeding into the subdural space may be very slow, gradually stop, and not cause acute symptoms. These 'chronic' subdural hematomas are often found incidentally on computerized tomography (CT) scans as part of a patient evaluation for confusion or because another traumatic incident occurred.

Intracerebral hematomas occur within the brain tissue itself. Intracerebral hematomas may be due to bleeding from uncontrolled high blood pressure, an aneurysm leak or rupture, trauma, tumor or stroke.

Scalp hematomas occur on the outside of the skull and often can be felt as a bump on the head. Because the injury is to the skin and muscle layers outside of the skull, the hematoma itself cannot press on the brain. However, a scalp hematoma signals that there has been a head injury and it is important to assure that internal bleeding has not occurred within the skull. 

Aural or ear hematomas may occur if an injury causes bleeding to the outside helix or cartilage structure of the ear. Often called boxer's, wrestler's ear, or cauliflower ear, blood gets trapped between the thin layer of skin and the cartilage itself. A hematoma can decrease blood flow causing parts of the cartilage to shrivel and die. This scenario results in a bumpy, deformed outer ear.

Septal hematomas occur with nasal trauma. A septal hematoma may form associated with a broken nose. If not recognized and treated, the cartilage can break down and cause a perforation of the septum.

Orthopedic injuries are often associated with hematoma formation. Bones are very vascular structures since the marrow is where blood cells are made. Fractures are always associated with hematomas at the fracture site. Fractures of long bones such as the thigh (femur) and upper arm (humerus) can be associated with a significant amount of bleeding.

Pelvic bone fractures can also bleed significantly since it takes a large amount of force to break these bones and it is very difficult to compress the area to decrease the amount of bleeding. Pelvic hematomas are hidden and the amount of blood loss may be difficult to assess.

Intramuscular hematomas can be very painful due to the amount of swelling and inflammation. Some muscles are surrounded by tough bands of tissues. If enough bleeding occurs, the pressure within these compartments can increase to the point that a 'compartment syndrome' can occur. This is most commonly seen in the lower leg and forearm.

Subungual hematomas are the result of rush injuries to the fingers or toes. Bleeding occurs under the fingernail or toenail and since it is trapped, pressure builds causing pain.

Bruises and contusions of the skin (ecchymosis) are terms that describe subcutaneous hematomas. These occur due to trauma or injuries to the superficial blood vessels under the skin. Individuals who take anti-coagulant medication are more prone to subcutaneous hematomas.

Intra-abdominal hematomas and hemorrhage may be due to a variety of injuries or illnesses. Hematomas may occur in solid organs such as the liver, spleen, or kidney. They may occur within the walls of the bowel, including the small intestine or the large intestine. Hematomas may also form within the lining of the abdomen called the peritoneum or behind the peritoneum in the retroperitoneal space.

Passing clots or hematomas is a common complaint when women menstruate. Blood can accumulate in the vagina as part of the normal menses and instead of flowing out immediately, it may form small blood clots. Passing blood clots after delivering a baby is also relatively common. However, vaginal bleeding and passing blood clots or hematomas while pregnant is not normal and should be a sign to seek medical attention.

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