Hematoma (cont.)
What causes a hematoma?
Trauma is the most common cause of a hematoma.
When people think of trauma, they generally think of car accidents, falls, head
injuries, broken bones, and gunshot wounds, etc.. Trauma to tissue may also
be caused by an aggressive sneeze or an
unexpected twist of a limb. When a blood
vessel is damaged blood leaks into the surrounding tissue; this blood tends
to coagulate or clot. The greater the amount of bleeding that occurs, the larger
the amount of clot formation.
Blood vessels that are fragile may contribute to
hematoma formation. For example, an aneurysm or weakening in a blood vessel wall may spontaneously leak.
There are many people who take blood thinners (anti-coagulation) medications. Examples include warfarin (Coumadin),
aspirin,
clopidogrel (Plavix) and
prasugrel (Effient). These medications increase the potential for spontaneous bleeding and
for hematomas to expand because the body cannot efficiently repair
blood vessels and blood continues to leak through the damaged areas.
Occasionally, diseases may occur that decrease the
number of platelets in the blood stream (thrombocytopenia) or their ability to function. The
platelets are the cells that help initiate
blood clot and fibrin formation.
All of the above situations may exist independently to cause a hematoma or they may
occur together.
What are the types of hematomas?
Hematomas are often described based upon their location.
The most dangerous hematomas are those that occur inside
the skull. Because the skull is an enclosed box, anything that takes up space
increases pressure within that box and potentially impairs the ability of the
brain to function.
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. The space below the dura has much more room for blood to
accumulate before brain function suffers. As people age, they lose some
brain tissue and the subdural space is relatively larger. 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 (intra= within + cerebrum=brain) 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. There are
a variety of guidelines available to the health care practitioner to assist in
accessing whether a patient will require further testing
to explore any bleeding in the brain.
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.
Since the ear cartilage gets its blood supply directly from the overlying skin,
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, sometimes up to one unit of
blood or 10% of the body's blood supply.
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. In this
situation, the blood supply of the muscle is compromised and the muscle and
other structures such as nerves can be permanently damaged. 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. Trephination, or drilling a hole through
the nail
to remove the blood clot, relieves the pressure and resolves the injury. A new
nail grows over time.
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. Regardless of how the blood gets into the abdomen, the
clinical finding is peritonitis
(irritation of the lining of the abdomen).
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 (duodenum,
jejunum, ileum) or the large intestine
(colon). Hematomas may also form within
the lining of the abdomen called the peritoneum or behind the peritoneum in the
retroperitoneal space (retro=behind).
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.
Hematomas may occur anywhere in the body. Regardless of how a hematoma is
described or where it is located, it remains a collection of clotted blood
outside of a blood vessel.
Next: What are the symptoms of a hematoma? »
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