have particular medico-legal significance. In former years the honeycomb grid of a motor-vehicle radiator provided many examples of patterned abrasions, but changes in vehicle design have relegated these to historical interest. There may still be projections on vehicles that cause damage, but these are more likely to inflict bruises and lacerations. The muzzle of a firearm can imprint an abrasion on the skin, which is of importance in that it confirms that the discharge was contact in nature. Impact against ribbed ceramic tiles in a bathroom or swimming bath may assist in reconstructing unwitnessed events. Blows from a weapon with a recognizable surface may
help to identify that weapon, such as a plaited rope or leather whip, or a solid object with an embossed pattern. Abrasions from objects with a recurring pattern, such as bicycle chain used in gang fights, or a serrated knife, can readily provide a clue to the nature of the weapon.
Post-mortem abrasions
Unlike post-mortem bruises, artefactual abrasions are com- mon. They may have been inflicted after death from a variety of causes, including dragging a corpse or buffeting in moving water. Some post-mortem animal injuries also resemble abra- sions such as insect bites, especially by ants.
Other damage may be caused following autopsy. As the post-mortem interval increases, so the skin becomes more fragile. Even the normal procedures of post-autopsy recon- struction and handling in the mortuary may cause dermal damage, especially after washing with hot water. If the path- ologist returns for a later examination, or if he is retained to perform a second autopsy for the defence, the appearances should be checked with the original description or photo- graphs, if some injuries suggest a post-mortem origin.
blood that is (arbitrarily) larger than a few millimetres in diameter, is usually termed a ‘bruise’ or ‘contusion’. This size overlaps the older and now little used term ‘ecchymosis’, which is really a small bruise.
Even smaller is the ‘petechial haemorrhage’, which is the size of a pin head or less. Both ecchymoses and petechiae are not usually caused by direct mechanical trauma and are often seen on serous membranes and conjunctivae as well as on skin. However, moderate pressure, impact or, especially, suc- tion on the skin can produce a patch of localized petechiae.
Bruises are caused by damage to veins, venules and small arteries. Capillary bleeding would be visible only under a microscope and even petechiae originate from a larger order of blood vessel than a capillary.
The word ‘bruise’ usually implies that the lesion is visible through the skin or present in the subcutaneous tissues, whilst a ‘contusion’ can be anywhere in the body, such as the spleen, mesentery or muscles. The two words are often interchanged at random, however, though ‘bruise’ is to be preferred when a doctor gives reports or evidence to a non- medical audience.
Intradermal bruises
These are important but rarely mentioned in most texts.
The usual bruise from a blunt impact is situated in the subcutaneous tissues, often in the fat layer. When viewed through the overlying corium and epidermis, the bruise is somewhat blurred, especially at the edge. When a bruise is made by impact with a patterned object, however, the haemorrhage may be far more sharply defined, if it lies in
the immediate subepidermal layer. The amount of blood is relatively small, but because of its superficial position and the translucency of the thin layer that overlies it, the pattern is distinct.
Such bruises are especially likely to occur when the impacting object has alternating ridges and grooves, as the skin will be forced into the grooves and be sharply dis- torted. Intradermal bleeding will occur here and the areas in contact with the raised ridges may remain pale, as the pressure forces the blood from the small vessels. A good example is that of a motor tyre running across the surface.
Impacts from whips with patterned thongs may also show the same phenomenon, as do the ribbed rubber soles of
‘trainer’ shoes.
Factors affecting the prominence of a bruise
Several factors influence the apparent size and prominence of a bruise and, because of these, it is not possible to be dogmatic about the amount of force needed to produce any given bruise.
■ As it is a leakage of blood from a vessel, there must be sufficient space outside that vessel for free blood to accumulate. This explains the ease with which bruising appears in lax tissues such as the eye socket or scrotum and its rarity in the sole of the foot or palm of the hand, where dense fibrous tissue and restrictive fascial planes prevent accumulation of blood. Because of the greater volume of soft subcutaneous tissue in fat people, they
FIGURE4.15 Intradermal bruising showing the pattern of rubber soles of
‘trainer’ shoes on the neck and T-shirt of a homicide victim.
tend to bruise more easily than thin ones, other factors being equal (such as vessel fragility and senile changes).
■ The apparent prominence of a bruise beneath the skin varies with the amount of blood in the extravasation.
The size of the haemorrhage depends partly, but not entirely, on the intensity of the injuring force. The size and density of the vascular network varies from place to place and the amount of damage that a given blow causes to local blood vessels is partly a matter of chance.
■ Resilient areas, such as the abdominal wall and buttocks, bruise less with a given impact than a region where underlying bone acts an anvil with the skin between the bone and the inflicting force. The head, chest and shins are examples.
■ The depth at which the bruise is placed affects the apparent severity. A bruise may be placed superficially in the dermis to form the well-patterned intradermal bruise mentioned in the previous section; here, a minute amount of blood will be obvious. Most bruises are in the subcutaneous tissues above the deep fascia and will therefore be fairly obvious, but others can be confined below deeper fascial membranes so that the free blood has to be viewed through the skin and underlying adipose tissue. For a given size of extravasation, this bruise will be less prominent. Some bruises are confined to deep fascial compartments and never become visible without dissection.
■ For a given impact, the volume of blood lost into the tissues can depend upon the fragility of the blood vessels and the coagulability of the blood.
In old persons, vessel fragility may be extreme and a large bruise may develop from the slightest of knocks. Children tend to bruise more easily than adults, presumably because of the softer tissues and the smaller volume of protecting tissue that overlies the vessels. Any bleeding diathesis resulting from disease, a toxic condition, or certain medication, will also retard the normal clotting process that heals the breach in the bleeding vessels. Those with scurvy and chronic alcoholics bleed easily but, in contrast, certain people (such as boxers) seem able to avoid bruising from blows that would severely damage other people.
■ It is common knowledge among lay people, as well as doctors, that a bruise may ‘come out’ – that is, become more prominent with the passage of hours or days. This is partly caused by continued bleeding from the ruptured vessels, but mainly by percolation of free blood from its origin deeper in the tissues upwards towards the epidermis. Another factor may be
haemolysis, when the freed haemoglobin is able to stain the tissues in a more diffuse way and become more noticeable than intact red blood cells. This latter mechanism is certainly the reason not only for the well- known post-mortem phenomenon of bruises becoming more prominent after death, but of new bruises appearing later where none was visible at an autopsy performed soon after death. This is further considered in the chapter on post-mortem changes, but is repeated here because of the importance of recognizing the differences in appearance that can occur between two autopsy examinations spaced a few days apart. The second, usually for a defence opinion, may find new bruises not recorded by the first pathologist, but if the phenomenon of delayed appearance is appreciated, potential disputes may be avoided.
Contusions or bruises
FIGURE4.16 Multiple bruises on the trunk of a victim of child abuse. The bruises are of the ‘fingertip’ type, caused by heavy prodding by adult fingers. The child died of a ruptured liver.
Movement of bruises
A bruise may appear at a different place on the surface from the point of impact. When the bruise is superficial, espe- cially intradermal bruising, the lesion appears immediately – or at least rapidly – and is at the point of infliction. When blood extravasates in the deep tissues, however, it may take time to reach the surface (if it ever does), and this may be some distance away because of deflection and obstruction by fascial planes and other anatomical structures.
In addition, bruises may move under gravity. The most frequent example is a bruise or a bleed under a laceration on the upper forehead. If the victim survives for at least some hours, then the subcutaneous haemorrhage can slide downwards over the eyebrow ridge and appear in the orbit, to give a ‘black eye’, which might be misinterpreted as direct trauma. Similarly a bruise of the upper arm or thigh may surface lower down around the elbow or knee.
Alteration of bruises with time
As already mentioned, bruises often become more promin- ent some hours or days after infliction because red cells or haemoglobin diffuse closer to the translucent epidermis.
There is another temporal series of changes in bruises in the living person, this being part of the healing process. Fresh extravasation of blood is obviously dark red, though when
viewed through the skin this may be purple or almost black in appearance. In racially pigmented victims, a bruise may sometimes be undetectable from the surface, apart from swelling caused by a haematoma and tissue oedema.
With the passage of time, the haematoma breaks down under the influence of tissue enzymes and cellular infiltra- tion. The red-cell envelopes rupture and the contained haemoglobin undergoes chemical degradation, which causes a sequence of colour changes. The haemoglobin is broken down into compounds including haemosiderin, biliverdin and bilirubin, which lead the colour changes through a spec- trum of purple to bluish brown, to greenish brown to green to yellow, before complete fading.
A small skin bruise in a healthy young adult might be expected to pass through all these stages and vanish in about a week, but there is a tendency to overestimate the length of time needed as shown by Roberts (1983), who observed that ‘love bite’ bruises in sexual offences could become yellow and vanish within a couple of days. Langlois and Gresham (1991) reviewed the literature on this subject, indicating the wide variation in opinion. They also made careful photographic records of the macroscopic appearance of bruising on 89 subjects, aged between 10 and 100 years.
They concluded that the most significant change was the appearance of a yellow colour (in persons less than 65 years of age), which indicated that the bruise could not be less than 18 hours old. Blue, purple and red did not assist in
FIGURE4.17 Patterned abrasion and intradermal bruising of the face during a fatal armed robbery. The watchman was struck in the face by an assailant wearing a hard-corded driving glove with a coarse- weave pattern.
dating bruises; brown was held to be a mixture of colours and was not considered as useful.
In the present authors’ experience, it is impossible to com- ment on the age of a bruise less than 24 hours since inflic- tion, except to say that it is ‘fresh’, as no visible changes occur in that time.
It is not practicable to construct an accurate calendar of these colour changes, as was done in older textbooks, as there are too many variables for this to be reliable. These include:
■ the size of the extravasation – changes begin at the margin and a larger bruise will take a longer time to be absorbed. A large old bruise may contain all the colours possible – from purple in the centre to yellow at the edges
■ the age and constitution of the victim. Aged persons may not heal their bruises at all and carry them for the remainder of their lives
■ a personal idiosyncrasy in the rapidity with which such changes occur in any one person, including coagulation defects.
Even histological examination is unreliable in the accurate dating of bruises, as is discussed later in this chapter. The appearance of stainable iron, in the form of haemosiderin, however, does not usually appear within the first 2 or 3 days, though Simpson suggests that it may be found as early as 24 hours. In meningeal haemorrhage, it seems to appear from around 36 hours.
Haematoidin, another breakdown product of blood pig- ment, can appear in old bruises and haematomas after the first week.
Though an absolute date cannot therefore be placed upon a bruise, the following observations are legitimate.
■ If a bruise appears fresh over all its area, with no observable colour change, it is unlikely to have been inflicted more than about 2 days before death, except in old persons.
■ If the bruise has any green discoloration, it was inflicted not later than 18 hours before death (Roberts 1983;
Langlois and Gresham 1991).
Contusions or bruises
FIGURE4.19 Extensive bruising of the face due to hitting, kicking and stamping 6 days earlier. The victim had multiple fractures of the facial bones, bilateral serial rib fractures and a tension pneumothorax.
FIGURE4.18 Kicking and stamping injury to the face. The nose is bruised from a kick and the patterned rubber sole of the shoe has imprinted intradermal bruising on the forehead. It is essential to obtain accurate photographs and measurements of the shoe-tread pattern, to allow identification of the footwear.
■ If several bruises (of roughly comparable size and site) are present and are of markedly different colours, then they could not have been inflicted at the same time.
This is particularly important in suspected child abuse, where intermittent episodes of injury have important diagnostic significance.
Bruising of special significance
Certain types of bruise and bruises at particular sites have a specific significance. Clusters of small discoid bruises of about a centimetre in diameter are characteristic of finger- tip pressure from either gripping or prodding. These groups are often seen in child abuse, when an adult hand grips the infant by a convenient ‘handle’. Once called ‘six- penny bruises’ from their size, the lesions are commonly seen on the forearms or upper arms of the child, or some- times around the wrist or ankle, though they can occur on the abdomen. Similar bruises from fingertips may be seen
on the neck of children or adults in manual strangulation, though there is often additional diffuse bruising caused by a sliding grip on the neck.
When the skin surface is struck by a rod or rectangular sectioned object such as a cane or lath, the consequent bruising may be of the ‘tram-line’ or ‘railway line’ type.
This appears as two parallel lines of bruising with an undamaged zone in the centre. The mechanism of this double line is that the weapon sinks into the skin on impact so that the edges drag the skin downwards and the traction tears the marginal blood vessels. The centre compresses the skin, which, in the absence of underlying bone, causes little or no damage to the vessels. When the momentary impact is released, blood flows back into the injured marginal zones and leaks into the tissues. Impact from broom han- dles, narrow planks and wood or metal rods can all cause this characteristic lesion.
As with abrasions, bites can result in bruises; this is dealt with in Chapter 26. It might be noted here that the so-called
‘love bites’ are often bruises, with or without associated abrasions, being a shower of small petechial lesions caused by oral suction on the skin.
The common ‘black eye’ is dealt with under ‘Head injuries’
in Chapter 5, but again it is worth repeating that not all black eyes are true bruising from a blow in the orbit. Some are from fractured orbital roofs and others are the result of gravita- tional movement of a forehead injury.
A bruise below the ear in a death from subarachnoid haemorrhage needs careful examination of the upper cervical spine and basilo-vertebral arteries, again as discussed under
‘Head injuries’ in Chapter 5.
FIGURE4.21 Suction marks in the left breast of a 22-year-old homicide victim, who was killed by manual and ligature strangulation.
FIGURE4.20 Bruises from a beating with a broom handle. They are approximately parallel and several, especially the lowermost, show a double ‘tram-line’ appearance typical of the impact of a round or square-section rod. The pressure in the centre compresses the vessels so that they do not bleed.