Bruises

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 extracellular space. Bruises can involve capillaries at the level of skin, subcutaneous tissue, muscle, or bone. Bruises may be referred to by size as ecchymosis (1-3 cm), purpura (3-10 mm), 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 extracellular space, 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 extracellular space, 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.

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

• 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 fair complexion.
• 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 fair complexion.

Severity of bruises

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

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 sprained, ligaments to be strained, 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; 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.