51 Minor Trauma: Bruises, Contusions, and Ecchymosis

Tissue Trauma

Trauma is often defined as injury to tissue that occurs suddenly due to an accident or an act of violence.  Trauma is the leading cause of death in young people aged 1 – 44.  Unintentional injuries can be serious, leading to hospitalizations or even fatality.  In Canada, the most common unintentional injuries result from falling. suffocation, motor vehicle crashes, poisonings, and burns.  Trauma can occur in many places, the home, outdoors, on the roads, during workplace accidents, domestic violence, and sports.  Contributing factors to traumatic injury can include repetitive motions or overuse, or insufficient training, equipment, protective clothing, headgear, or footwear.  Trauma can result from physical and/or sexual assault, warfare, or natural disasters.  Trauma is typically accompanied by physiological and psychological responses.

Trauma can range from mild to severe and can even be fatal.  Major trauma is typically defined as trauma that causes either permanent or short-term disability.

Minor Trauma typically includes injuries that are not life-threatening and may or may not require a trip to the hospital’s emergency room.  Minor Trauma does require medical attention in the form of procedures that help speed healing, prevent infection, and reduce the risk of complications.  Typically this involves the appropriate cleaning of wounds, applying of sterile dressings, cold compresses, providing protection and/or realignment (e.g., suturing, bandaging, splinting, casting) if required and supplemental treatments (e.g., emotional support, counselling, rehabilitative therapies, nutrition, and possibly analgesics or anti-inflammatories if required).

Minor trauma can include lacerations, scrapes (abrasions), and cuts that may or may not require sutures.  At times trauma is described as either penetrating trauma if there is an open wound or blunt trauma (blunt force trauma) if there is no open wound and no penetrating injury of the body’s surface.  In terms of signs and symptoms, trauma, particularly blunt trauma, is often accompanied by bruises (also called contusions or ecchymoses).  Sports injuries, motor vehicle accidents and falls can also result in sprains, strains, bone fractures, as well as more serious injuries to brain, spinal cord, peripheral nerves, skeletal muscle or other internal organs.

Over the next several pages we will examine musculoskeletal injuries, including risk factors, signs and symptoms, pathogenesis, stages of healing, diagnostic tools, recommended treatments and rehabilitative strategies.

Terms for Internal and External Bleeding

A bruise (also called a contusion) occurs when tissue is injured and damaged capillaries within the area leak (extravasate) blood.  This localized bleeding into the surrounding interstitial tissue is sometimes called a hematoma, which a benign collection of blood that although initially fluid, will coagulate and become more solid.  Bruises (contusions) can occur in any tissue of the body (e.g., skin, brain, bone, muscle etc.) and are typically only visible as black or blue colourations if located in the skin.

The term ecchymosis (plural, ecchymoses) originates from Ancient Greek words ‘ec’ and ‘chymos’ for juice (together meaning extravasate blood or leak blood).  Ecchymosis is defined as a hematoma within the skin that is larger than 1 cm.  However, even though ecchymosis is often used interchangeably with hematoma, it is sometimes used to refer to blood that accumulates in a region that is distant from the initial injury (e.g., bruising around the eyes, ‘racoon eyes’, that can occur as a result of a basilar skull fracture).

The black and blue colouration observed with contusions (bruises), hematomas, and ecchymoses is due to the light reflecting from the heme pigment molecule of hemoglobin which has accumulated in the area of leaked blood.  Bruises and hematomas range in colour, with darker colours associated with a greater amount of accumulated blood and therefore increased damage and bleeding.  Let’s quickly review hemoglobin and heme to better understand the changing colouration of bruises.

Hemoglobin is a protein consisting of four polypeptides (two alpha-globin polypeptides and two beta-globin polypeptides), with each of these four polypeptides, bound to 1 heme molecule each, resulting in a total of 4 heme molecules per hemoglobin protein.  As each heme molecule can bind to one O₂ molecule, each hemoglobin protein can carry a maximum of four O₂ molecules when fully saturated with oxygen, a condition referred to as oxyhemoglobin.  This occurs during circulation, as red blood cells (RBCs, erythrocytes) are oxygenated in the lungs.  There are 260 million hemoglobin proteins packed into each RBC, as hemoglobin makes up the majority (~96%) of the volume of each RBC.  In the lungs, within the alveolar capillaries, the RBCs’ hemoglobin becomes fully saturated with oxygen.  This is helpful as the RBCs can then carry this oxygen through blood vessels to all of the tissues of the body, where cells can take up the oxygen to use in enzymatic reactions to produce ATP for the cell.  As oxygen leaves RBCs to enter cells of the body, hemoglobin is losing some of it’s oxygen (not all), the amount of hemoglobin saturated with oxygen goes from 95-100% down to 50-75% saturated (depending on how active the tissue beds are and how much oxygen the cells take up).  At the same time, RBCs take up carbon dioxide (CO₂) that the body’s cells have produced.  This CO₂ will be eliminated from the body, during exhalation.  RBCs will complete the journey, leaving the tissue beds to return to the heart to be pumped back to the lungs to become fully saturated with again.   When hemoglobin is at 50-75% saturation, it is termed deoxygenated.

Colours of Oxygenated and Deoxygenated Blood

In test tubes, deoxygenated blood is noted to have a dark red appearance, whereas oxygenated blood has a bright red appearance.

The colour seen is largely due to which wavelengths of light that are absorbed and reflected by the four iron-containing heme pigments of each hemoglobin molecule.  In the deoxygenated state, when oxygen (O₂) is not bound to the iron atom of heme, it is replaced with water (H₂O) and water binds to the iron (not CO₂).  The binding of oxygen to the iron atom changes the shape of the heme pigment affecting the wavelengths of light that are absorbed and reflected.

Oxygenated hemoglobin absorbs more of the higher wavelengths (960nm) than the lower wavelengths (660nm) in comparison with deoxygenated hemoglobin.  Therefore, when viewed in a test tube, oxygenated blood has a bright red appearance and deoxygenated blood has a dark red hue.

One may notice that through the skin, the blood in veins can look blue instead of red, which has to do with longer wavelengths of the visible light spectrum penetrating the skin farther and being absorbed into our skin and accumulated blood with shorter blue light (450-495nm) bouncing back to our eyes.

Bruise Colours

Very Dark or Black Bruises:  If a lot of internal bleeding has taken place in an area that is visible through the skin, the first appearance of a bruise may be very dark or black in colour.  This dark colour is due to the accumulated blood (and heme) absorbing many/most wavelengths of the visible spectrum, and the absence of light bouncing back to the eye is interpreted by the eye as black.

Blue or Purple Bruises:  If the bleeding is not as severe, a bruise may initially appear blue or purple, instead of having black tone.  The blue or purple colour is due to longer wavelengths of the visible light spectrum penetrating the skin farther and being absorbed by the accumulated blood and tissues, with just the shorter blue light (450-495nm) bouncing back to our eyes. If the bruise appears purple, both blue and violet light (380-435nm) being reflected back to our eyes.

Green or Yellow Bruises:  As days pass after the injury, the colour of the bruise will change.   The leaked RBCs within a bruise hematoma will be phagocytosed and recycled by macrophages and other phagocytes.  During this process, the alpha and beta polypeptides of hemoglobin are broken down into amino acids for re-use or excretion.  The central heme pigments are separated from the iron atoms to become biliverdin.  Biliverdin gives the bruise a green colour.  Biliverdin is then converted to bilirubin, and the bilirubin that is present gives the bruise a yellow colour.  This unconjugated-bilirubin is a waste product that the liver will convert to conjugated-bilirubin, which will become a major component of bile which is sent to the gallbladder and then small intestine to be used in the process of digestion and then be excreted.

Bruises and Inflammation

Contusions (bruises) are also the sites of local inflammation often exhibiting all of the signs of inflammation (i.e., swelling, warmth, redness, pain and sometimes loss-of-function).  During inflammation, the damaged endothelial cells of blood vessel walls release the hormone endothelin which causes vasospasm (vasoconstriction) to reduce bleeding.  Reducing bleeding further is achieved through the formation of platelet plugs anchored in place with ropy fibrin plasma protein to seal damaged blood vessel walls.  This temporary clot seals the wound until regenerative cell proliferation takes place and the damaged cells can be phagocytosed by macrophages, and replaced by new cells.  The new cells fill in the space and differentiate to becoming mature, and restore strength and function to the tissue.  Scarring may occur in wounds where full regenerative replacement of lost cells is not possible.  The scar tissue is predominantly made of fibroblasts and the ropy collagen extracellular matrix proteins that they produce.

Bruises – Treatment

The treatment for bruises will depend on the severity of the injury but often involves RICE or PRICE and may include NSAIDs (non-steroidal anti-inflammatory drugs, e.g., Advil, Motrin) which are analgesics and can also help to reduce inflammation.

RICE is an acronym, standing for Rest, Ice, Compression, and Elevation.  Rest is thought to help with helpful in the initial stages of healing, in preventing further injury, and reducing pain.  Ice refers to cold treatments such as cold compresses, which help minimize and reduce inflammation as well as decrease activity in nociceptors, reducing pain.   Compression using elastic bandages or similar items can also minimize swelling as well as provide some protection and support during movement.  Compression should be firm, but loose enough that it does not cause pain, numbness, or pallor.  Elevation of the injured site can help reduce swelling, which in itself can reduce pressure and triggering of nociceptors, minimizing pain.  Elevation also can reinforce rest of the site as well and the associated benefits of temporary rest.

The acronym PRICE adds a 5th level of care, Protection, which is means to protect the injured site from further damage and this may include limiting weight-bearing or motions that could exacerbate the injury.  Protection can include splints, slings, braces, casts, crutches, canes, walkers, scooters or other mobility devices.

Bruising – Susceptibilities affecting Severity

The same force can cause more severe bruising in some people in comparison with others.  Aging leads to thinner and less elastic skin putting one at risk for more bruising to occur, which also is slower to heal.  Infants and children can also be at risk for more bruising due to thinner skin than adults.  Individuals with more subcutaneous fat tend to bruise more, as fat is very well vascularized.   Those with underlying health issues (e.g. platelet or clotting factor deficiencies) are also more susceptible to bruising (and bleeding).  Care and attention should be used when assessing bruises for severity or timing, as bruises may appear differently on different skin tones, and underestimating the severity of bruises could lead to insufficient treatment.

Example of Non-Cutaneous Contusions

Bone Contusion (Bone Bruise): often results from trauma (e.g., sports or vehicle injury) and involves small amounts of damage done to any part of the bone, specifically involving the breakage of some capillaries and some trabeculae.  The microfracture that results is not a full bone fracture and is less severe, though a hematoma may form.  Bruising of the overlying tissue and signs of inflammation may be detected by eye.  The bone bruise itself typically can’t be seen in an x-ray and is only viewable on a more sensitive MRI image. Treatment typically involves PRICE and NSAIDs as required.  Full recovery is expected.

External Bleeding

Hematomas and ecchymoses are a result of internal bleeding.  If the skin is broken in the area of the injury, bleeding may become external and the formation of a hematoma may not occur.  The term hemorrhage, is used when the bleeding that is occurring is severe, regardless of whether the bleeding is internal or external.   Small nosebleeds (epistaxis) are common in trauma that involves the nose, as the nasal mucosa is well vascularized and the nasal mucosa can be thin and fragile particularly in the elderly.

Lesions of Capillaries

*Side note:  Not all capillary bleeds are caused by trauma and are therefore not considered bruises.  While similar in appearance to bruises, petechiae and purpura more often are caused by infections, DIC (disseminated intravascular coagulation), platelet deficiencies, vasculitis, or vascular disorders (at times due to autoimmune diseases).  Small capillary bleeds that cause tiny red or purple spots (less than 3mm in diameter) are called petechiae that can be seen if in the skin or mucosa.  The term petechia (petechiae plural) originates from the Italian word ‘petecchia’ (meaning ‘speck’ or ‘freckle’) and Latin word ‘impetere’ (meaning ‘to attack’).  Larger red or purple spots (3-10mm in diameter) called purpura are also caused by slightly larger capillary bleeds.  Purpura means purple in Latin.