Bruise

"Black and blue" redirects here. For other uses, see Black and Blue (disambiguation).

"Bruises" redirects here. For the 2008 rock song, see Bruises (song).

Bruise
Classification and external resources
File:Ladder fall bruise.jpg Bruises from a ladder fall
ICD-10	S00.-S90., T14.0
ICD-9	920-924
DiseasesDB	31998
MeSH	D003288

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, or bone. A bruise may be named by the length of its diameter as an ecchymosis (1 to 3 cm), purpura (3 mm to 1 cm), or petechia (< 3 mm), although these terms can also refer to internal bleeding not caused by trauma.

As a type of hematoma, a bruise is always caused by internal bleeding into the interstitial tissues, usually initiated by blunt trauma, which causes damage through physical compression and deceleration forces. Trauma sufficient to cause bruising can occur from a wide variety of situations including accidents, falls, and surgeries. Disease states such as insufficient or malfunctioning platelets, other coagulation deficiencies, or vascular disorders, such as venous blockage associated with severe allergies can lead to the formation of bruises in situations in which they would not normally occur and with only minimal trauma. If the trauma is sufficient to break the skin and allow blood to escape the interstitial tissues, the injury is not a bruise but instead a different variety of hemorrhage called bleeding, although such injuries may be accompanied by bruising elsewhere.

Bruises often induce pain, but small bruises are not normally dangerous alone. Sometimes bruises can be serious, leading to other more life-threatening forms of hematoma, such as when associated with serious injuries, including fractures and more severe internal bleeding. The likelihood and severity of bruising depends on many factors, including type and healthiness of affected tissues. Minor bruises may be easily recognized in people with light skin color by characteristic blue or purple appearance (idiomatically described as "black and blue") in the days following the injury.

Mechanism of bruise

Increased distress to tissue causes capillaries to break under the skin, allowing blood to escape and build up. As time progresses, blood seeps into the surrounding tissues, causing the bruise to darken and spread. Nerve endings within the affected tissue detect the increased pressure, which, depending on severity and location, may be perceived as pain or pressure or be asymptomatic. The damaged endothelium (lining) of the affected capillaries releases endothelin, a hormone that causes narrowing of the blood vessel to minimize bleeding. As the endothelium is destroyed, the underlying von Willebrand factor is exposed and initiates coagulation, which creates a temporary clot to plug the wound and eventually leads to restoration of normal tissue.

During this time, larger bruises may change color due to the breakdown of hemoglobin from within escaped red blood cells in the extracellular space. The striking colors of a bruise are caused by the phagocytosis and sequential degradation of hemoglobin to biliverdin to bilirubin to hemosiderin, with hemoglobin itself producing a red-blue color, biliverdin producing a green color, bilirubin producing a yellow color, and hemosiderin producing a golden-brown color. As these products are cleared from the area, the bruise disappears. Oftentimes the underlying tissue damage has been repaired long before this process is complete.

Size and shape of bruises

Bruise shapes may correspond directly to the instrument of injury or be modified by additional factors. Bruises often become more prominent as time lapses, resulting in additional size and swelling. Bruising present in a different location than the site of impact is called ectopic bruising and occurs when the tissue at the site of injury is loose, allowing blood to travel under the skin to another location due to gravity or other forces, such as in a black eye.

General factors modifying size and shape of bruises

File:Severebruise.jpg

Bruise caused by a handrail, typical of extreme sports

File:Bruises.jpg

Severe bruises caused by car accident

File:Snowboarding2.jpg

Bruise caused by a bad landing while snowboarding

• Condition and type of tissue: In soft tissues, a larger area is bruised than would be in firmer tissue due to ease of blood to invade tissue.
• Age: elderly skin and other tissues are often thinner and less elastic and thus more prone to bruising.
• Gender: More bruising occurs in females due to increased subcutaneous fat.
• Color of skin: Although the same size, bruises are more prominent in lighter complexions.
• Diseases: Coagulation, platelet and blood vessel diseases or deficiencies can increase bruising due to more bleeding.
• Location: More extensive vascularity causes more bleeding.
• Forces: Greater striking forces cause greater bruising.
• Genetics: Despite having completely normal coagulation factors, natural redheads have been shown to bruise more, although this may just be due to greater visibility on commonly associated lighter complexion.

Severity of bruises

Bruises can be scored on a scale from 0-5 to categorize the severity and danger of the injury.

Bruise harm score

Harm score	Severity level	Notes
0	Light bruise	No damage
1	Less than Moderate bruise	Little damage
2	Moderate bruise	Some damage
3	Serious bruise	Dangerous
4	Extremely serious bruise	Dangerous
5	Critical bruise	Risk of death

The harm score is determined by the extent and severity of the fractures to the organs and tissues causing the bruising, in turn depending on multiple factors. For example, a contracted muscle will bruise more severely, as will tissues crushed against underlying bone. Capillaries vary in strength, stiffness and toughness, which can also vary by age and medical conditions.

Light bruises

Low levels of damaging forces produce small bruises and generally cause the individual to feel minor pain, either initially or delayed. Repeated impacts worsen bruises, increasing the harm level. Normally, light bruises heal nearly completely within two weeks, although duration is affected by variation in severity and individual healing processes; generally, more severe or deeper bruises take somewhat longer.

Moderate to severe bruises

Severe bruising (harm score 2-3) may be dangerous or cause serious complications. Further bleeding and excess fluid may accumulate causing a hard, fluctuating lump or swelling hematoma. This has the potential to cause compartment syndrome as the swelling cuts off blood flow to the tissues. The trauma that induced the bruise may also have caused other severe and potentially fatal harm to internal organs. For example, impacts to the head can cause traumatic brain injury: bleeding, bruising and massive swelling of the brain with the potential to cause concussion, coma and death. Treatment for brain bruising may involve emergency surgery to relieve the pressure on the brain.

Damage that causes bruising can also cause bones to be broken, tendons or muscles to be strained, ligaments to be sprained, or other tissue to be damaged. The symptoms and signs of these injuries may initially appear to be those of simple bruising. Abdominal bruising or severe injuries that cause difficulty in moving a limb or the feeling of liquid under the skin may indicate life-threatening injury and require the attention of a physician.

Treatment

Treatment for light bruises is minimal and may include RICE (rest, ice, compression, elevation), painkillers (particularly NSAIDs) and, later in recovery, light stretching exercises. Particularly, immediate application of ice while elevating the area may reduce or completely prevent swelling by restricting blood flow to the area and preventing internal bleeding. Rest and preventing re-injury is essential for rapid recovery.

Very gentle massage of the area and application of heat may encourage blood flow and relieve pain according to the gate control theory of pain, although causing additional pain may indicate the massage is exacerbating the injury. As for most injuries, these techniques should not be applied until at least three days following the initial damage to ensure all internal bleeding has stopped, because although increasing blood flow will allow more healing factors into the area and encourage drainage, if the injury is still bleeding this will allow more blood to seep out of the wound and cause the bruise to become worse.

As a medical sign

The presence of bruises may be seen in patients with platelet or coagulation disorders. Unexplained bruising may be a warning sign of child abuse, domestic abuse, or serious medical problems such as leukemia or meningoccocal infection. Unexplained bruising can also indicate internal bleeding or certain types of cancer. Long term glucocorticoid therapy can cause easy bruising. Bruising present around the navel (belly button) with severe abdominal pain suggests acute pancreatitis.

During an autopsy, bruises accompanying abrasions indicate the abrasions occurred while the individual was alive, as opposed to damage incurred after death.

See also

• Black eye
• Burn
• Subconjunctival hemorrhage
• Love-bite
• Pulmonary contusion—a bruise of the lung tissue
• Cerebral contusion—a bruise of the brain tissue
• Myocardial contusion—a bruise of the heart muscle

External links

• Firstaidweb on bruises
• What is a bruise? for kids
• Bruises in sports
• NiceBruise.com - Where bruise sufferers go to show off their bruise

cs:Podlitina zh:瘀斑