Hematoma

Definition

By definition, a hematoma is a collection of blood outside of a blood vessel. It occurs because the wall of a blood vessel wall, artery, vein or capillary, has been damaged and blood has leaked into tissues where it does not belong. The hematoma may be tiny, with just a dot of blood or it can be large and cause significant swelling.
The blood vessels in the body are under constant repair. Minor injuries occur routinely and the body is usually able to repair the damaged vessel wall by activating the blood clotting cascade and forming fibrin patches. Sometimes the repair fails if the damage is extensive and the large defect allows for continued bleeding. As well, if there is great pressure within the blood vessel, for example a major artery, the blood will continue to leak and the hematoma will expand.
Blood that escapes from the blood stream is very irritating and may cause symptoms of inflammation including pain, swelling and redness. Symptoms of a hematoma depend upon their location, their size and whether they cause associated swelling or edema.

articlekey=3682Bruises and contusions
The medical term ecchymosis is what most people would recognize as a bruise, or blood that has leaked out of a broken blood vessel under the skin that is caused by an injury. Another word for this injury is a contusion. An ecchymosis tends to be flat while a hematoma has more of a three dimensional character to it. As well, hematomas may occur in any organ and not just under the skin.
Hemorrhage
Hemorrhage is the term used to describe active bleeding. The term hematoma describes blood that has already clotted.

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.

What are the symptoms of a hematoma?

Hematomas cause irritation and inflammation. Symptoms depend upon their location and whether the size of the hematoma or the associated swelling and inflammation causes structures nearby to be affected. The common symptoms of inflammation include redness, pain, and swelling.
In general, superficial hematomas of skin, soft tissue, and muscle tend to resolve over time. The initial firm texture of the blood clot gradually becomes more spongy and soft as the clot is broken down by the body and the shape changes as the fluid drains away and the hematoma flattens. The color changes from that of a purplish-blue bruise to yellows and browns as the blood chemicals gradually are removed and the hematoma resolves. Depending upon its location, the discolorations may travel through different tissue planes by gravity. For example, a forehead hematoma may cause bruising beneath the eyes and seem to travel to the neck as it resolves over time.
Intracranial, epidural, subdural, and intracerebral hematomas often need neurosurgical intervention to stabilize the injury.

When should I call my doctor about a hematoma?

Most hematomas have little consequence. They are due to minor trauma where the patient was aware of the injury, knows what part of the body was injured and can expect to recover with few problems. Bumps and bruises are part of every child's growth.
Some hematomas may be more important because of their location and it is usually the nearby affected structures that cause symptoms. For example, medical care would be sought for a head injury victim for significant headache, vomiting , or difficulty being aroused. Intracranial (intra= within + cranium=skull) hematomas need to cause pressure on the brain before symptoms manifest themselves, thus any significant head injury should be evaluated by a health care practitioner.
Patients taking blood thinners are at higher risk for bleeding from minor injuries. It is often wise for these people to seek medical attention if they are involved in even minor accidents or sustain minor injuries.

How is a hematoma diagnosed?

Hematomas of the skin and soft tissues, such as muscle and joints, are often diagnosed by physical examination alone.
For patients exhibiting signs of internal bleeding, the health care practitioner will decide what imaging modality is best to evaluate the situation. Plain X-rays may be needed to assess for bone fracture. Patients with significant head injury often require CT scanning. Ultrasound is the testing modality of choice for pregnant patients.

What is the treatment for a hematoma?

Hematomas of the skin and soft tissues are often treated with RICE (rest, ice, compression, elevation). Some health care practitioners may advocate heat as another treatment alternative. The pain of a hematoma is usually due to the inflammation surrounding the blood and may be treated with over the counter pain medications. The choice of medication depends upon the underlying health of the patient. For those patients who are taking anti-coagulation medications, ibuprofen is relatively contra-indicated because of the risk of gastrointestinal bleeding. Patients with liver disease should not take over the counter acetaminophen. When in doubt, it is wise to ask the health care practitioner or pharmacist for a recommendation.
Treatment for hematomas involving other organs in the body depends upon what organ system is involved. In these cases, treatment will be tailored to the specific situation.

What are the complications of a hematoma?

Hematomas cause swelling and inflammation. It is often these two consequences that cause irritation of adjacent organs and tissues and cause the symptoms and complications of a hematoma.
One common complication of all hematomas is the risk of infection. While the hematoma is made of old blood, it has no blood supply itself and therefore is at risk for colonization with bacteria.

Can hematomas be prevented?

Accidents happen and most hematomas are inevitable once the trauma has occurred.
For patients taking anti-coagulation medications, it is wise to avoid participating in events with high risk of injury. For patients taking warfarin (Coumadin), it is important to make certain that the dosing is appropriate and the blood is not thinned excessively.

Hematoma At A Glance

• A hematoma is a collection of blood outside of a blood vessel.
  
• Symptoms of hematomas depend upon their location and whether adjacent structures are affected by the inflammation and swelling associated with the bleeding.
  
• Treatment of a hematoma depends upon which organ or body tissue is affected.
  
• Superficial hematomas of the skin and soft tissue, such as muscle, may be treated with rest, ice compression, and elevation. Heat may also be considered.

References:

Rosen's Emergency Medicine: Concepts and Clinical Practice, 6th Edition, 2006.

Emergency Medicine: a Comprehensive Study Guide 6th Edition, 2003.

REFERENCES:

Andreoli, Thomas E., et al. Andreoli's and Carpenter's Cecil Essentials of Medicine. Saunders; 7 edition, 2007.