A bruise is generally understood to mean an area of haemorrhage caused by the leakage of blood from ruptured vessels (including capillaries, but predominantly veins, venules and small arterioles) - into surrounding (perivascular) tissues, following a 'blow'.


The picture above is of a bruise with a mixture of colours, which is diffusing at the yellowing edges, indicating that this was probably inflicted several days before this photograph was taken.


types of bruises


1. petechial haemorrhages

This term is used to describe very small 'pinpoint' (i.e. less than about 2mm) extravasations of blood, most often seen on the skin, conjunctivae and mucous/ serous membranes, arising at the level of the capillaries.

Their pathogenesis is poorly understood, but may relate to raised intra-capillary pressure due to an obstruction of venous return (subsequent to pressure applied to the upper chest or neck, for example), hypoxia, endothelial dysfunction (in sepsis) or a combination of these factors (Jaffe 1994).

Petechiae can also be caused by blunt trauma (Jaffe 1994, Saukko and Knight 2004), implying a mechanical disruption of capillaries.

The presence of petechiae has been reported in a wide variety of situations including;

Although they appear to be a non-specific manifestation of capillary damage or dysfunction, their presence demands an explanation, and in particular prompts a careful examination of the anterior neck structures in order to exclude pressure having been applied to the neck.


(See National Library of Medicine (USA) - image of petechial haemorrhages, and University of Toronto 'Anatomia' - anatomy of the larynx )


2. intradermal bruises

Where an extravasation of blood arises within the deeper dermis, allowing extension of blood into subcutaneous tissues, the 'outline' of the briuse seen at the skin surface is usually 'blurred' or indistinct.

If the bleeding occurs more superficially, however, the result is a so-called 'intradermal bruise', where the components of the bruise are more easily deliniated (punctiform, sharply defined and 'bright red in colour'). A 'negative image' of the profile of the impacting instrument is produced i.e. a 'patterned injury' (Bohnert et al 2000).

In these injuries, usually caused by an impact to the skin by an implement that has a surface consisting of 'grooves' or 'ridges', the outline of the implement may be 'retained'.

The finding of a 'patterned' injury is of considerable forensic interest - careful documentation and photography of such a wound may allow subsequent matching of a putative injury-causing implement with the skin surface bruise (a form of 'tool mark' analysis utilising computer-enhanced photographic 'overlay' techniques).

Examples of situations in which an intradermal bruise may be produced (Saukko and Knight 2004, Thali et al 2000);

  • tyre marks in a road traffic collision
  • a punch to the face by a woolen-gloved fist
  • a 'stamp' by a shoe/ trainer etc
  • an impact by a whip


Patterned bruising with injury-causing implement (belt buckle)

Source: Forensic Medicine, Raisky MI 1953 (USSR) via ebay


3. tramline bruises

When a person is struck with a cylindrical object, such as an iron bar, baseball bat, or police asp etc, the bruise pattern formed is quite distinct.

The skin surface is indented and blood vessels at the edges are ruptured. Blood is squeezed out of any vessels along the point of contact, but the vessels remain relatively intact (particularly if the supporting tissues are lax). When the impacting object is removed, blood flows back into the undamaged vessels, but leaks from the damaged ones.

The resulting bruise is termed a ‘tramline bruise’ because it appears as a pale linear central area lined on either side by linear bruising

(See a picture of tramline bruising)



4. fingertip/pad bruises

Where an assailant has forcefully gripped a person, for example around the neck (e.g. during attempted manual strangulation) or arms etc, one may see small discoid or ovoid bruises in a cluster. These may be discrete, but are often blurred or may 'merge' with one another, due to the dynamic nature of assaults and struggles with an assailant. Sites to look for these bruises include,



5. Others

  • ‘Defensive’ bruises on the upper arms or forearms, where a victim has attempted to ward off their attacker’s blows to protect vital organs/ body parts
  • Bruising around the mouth or lips, which may corroborate a history of having had a hand forcibly placed over their mouth to silence the victim
  • Bruising on the shoulder prominences, which may corroborate a history of having been forcibly pushed up against a wall etc during an assault


In addition, the following 'signs' describe subcutaneous haemorrhage resulting from blood tracking from distant sites of injury, but do not represent 'bruises' of the site at which the skin discolouration is visible (Dolinak and Matshes 2005);


  • Battle’s sign (named after William Henry Battle) – bruising visible behind and below the ear at the mastoid process, caused by the gravitational accumulation of blood from a basilar skull fracture,






Bruises caused by injury should also be distinguished from skin discolouration seen in ‘Mongolian blue spots’ in children, ‘Campbell de Morgan spots’, striae and (senile) purpura. Further details of these innocent lesions can be obtained from standard dermatology and paediatric texts.

(See Derm Atlas for an image of a Mongolian Blue spot)


CT/ MRI visualisation of bruises:

  • Yen et al 2004
  • Thali et al 2004 (Tyre marks)
  • Oliver et al 1997 (Tramline bruising)
  • Thali et al 2005 (Footwear imprints/ intradermal bruises)

factors affecting the appearance of bruises


  • The laxity of tissues – lax scrotal tissues allow more extravasation of blood that, for example the dense fibrous tissues of the soles of the feet, or palms of the hand. Restrictive fascial planes prevent the accumulation of extravasated blood. The Turkish torture method ‘falaka’ relies on this principle – the soles of the feet are targets of a beating with sticks, causing severe pain but little outward sign of any injury (Thomsen 2003 p.60);
  • The location of the bruise – highly vascular areas will be more heavily bruised, and tissues overlying bony support will bruise more readily than the unsupported and resilient tissues of the abdomen. It should also be noted that extravasated blood follows the path of fascial planes and is affected by gravity, therefore the site of the bruise is not necessarily indicative of the locus of impact (e.g. An impact on the scalp may result in a bruise appearing in the soft tissues of the eye etc);
  • The injured person’s age – bruises take longer to resolve in the elderly who tend to have more fragile vessels (and may remain with them for the rest of their lives). Children have a comparatively smaller volume of 'supporting tissue';
  • The person’s skin pigmentation – bruises are not as easily recognised in those with pigmented skin, although their presence may be suspected by the presence of oedema and swelling;
  • The force of impact – the amount of force used may determine the extent of bruising, as well as the characteristics of the implement causing the bruise to form. The extent of bruising is also inversely proportional to the sharpness of the object causing it – bruises represent blunt force trauma;
  • The existence of co-morbidities – some people have the tendency to bruise more easily than others, particularly those with bleeding diatheses, chronic alcoholism and liver failure, scurvy and hypertension. In the clinical setting clotting studies and liver function tests can augment the history and examination if there is any doubt about a person’s tendency to bleed/ bruise. A full blood count will also indicate platelet abnormalities, but see Khair and Liesner (2006) for an approach to the investigation of bleeding/ bruising in children;
  • The use of drugs – particularly anticoagulants such as warfarin and steroids;
  • Any delay in presentation – bruises ‘migrate’ along anatomical fascial planes, and may appear some time after the injurious assault; and
  • The effects of treatment – for example the timely application of ice-packs etc

conditions in which there is a tendancy to bruise


Bruises can be caused by abnormal bleeding, bleeding diatheses and tissue fragility disorders. Haematological studies must therefore always be undertaken in any refuted case of bruising in order to rule out any such condition. (Nathanson 2000 pp.156-57, Connolly et al 2003 p. 725). However, it should be noted that the presence of a coagulation deficit does not exclude an abusive aetiology, and evidence of a bleeding disorder is not uncommon in non-accidental injury (in children) (O'Hare and Eden 1984; Sibert 2004).

The function of normal haemostasis (see box below) is to maintain blood in a fluid, clot-free state within normal blood vessels, and to induce rapid and localised haemostatic clots or plugs at the site of any vascular injury (Kumar et al 2005 p.124; Hampton and Preston 1997).

Khair and Liesner (2006) describe an approach to the investigation of bruising and bleeding in infants and children, from a haematological perspective. They divide the investigative process into those with a low platelet count, those with abnormal coagulation and those with normal platelet counts and coagulation, listing further subsequent tests to carry out.


Brief arteriolar vasoconstriction (reflex neurogenic mechanisms augmented by secretion of endothelin (endothelium derived vasoconstrictor))
Endothelial injury exposes subendothelial extracellular matrix allowing platelet adherence. Platelet activation results in further platelet recruitment to form a haemostatic plug (primary haemostasis)
Endothelium synthesises ‘tissue factor’ which activates the coagulation cascade (extrinsic pathway) in conjunction with platelet factors culminating in thrombin activation
Thrombin converts circulating soluble fibrinogen to insoluble fibrin resulting in local fibrin deposition. It also induces further platelet recruitment (secondary haemostasis)
Polymerised fibrin and platelet aggregates form a solid permanent plug to prevent further haemorrhage
Counter-regulatory mechanisms (fibrinolysis) restrict the clot to the site of injury e.g. Tissue plasminogen activator (t-PA)

Normal haemostasis (Kumar et al 2005)

Those suffering from bleeding diatheses have an increased tendency to haemorrhage. For overviews of haematological conditions complicated by bleeding and/ or bruising, see Khair and Liesner (2006), and Hampton and Preston (1997).

In addition, case reports (Connolly et al 2003) also note the presence of bruises associated with non-haematological malignancies such as solid tumours (or their metastases).


Derm Atlas image - Henoch-Shonlein Purpura 

Derm Atlas image - 'cupping'

Derm Atlas image - autoimmune thrombocytopenic purpura and petechiae


sequelae of severe bruising


When there has been severe blunt force trauma resulting in deep muscle bruising, rhabdomyolysis can develop, potentially leading to acute renal failure (Bowley et al 2002).




bruise definition


'Bruise' probably originates from the old English word 'brysan', meaning 'to break or smash' and defines the verb 'to bruise' as meaning to 'injure or damage with a heavy blow or weight'.


Shorter Oxford English Dictionary 1993

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