Forensic pathology regards the diagnosis of when a lesion occurred and how it occurred. All physicians will have to deal with violence and trauma at some point. It is important you can describe a lesion well and accurately as your report may be used as evidence in a court case. You should be able as a doctor to diagnose a lesion, age it, describe it and know what to do to preserve evidence.
Forensic pathology starts with a physical exam. You need to assess the whole body (you also need to listen to the patient, don’t forget!). If you don’t document a lesion or ‘crime’ and the victim doesn’t talk, then any evidence of the ‘crime’ will disappear. No sign of a crime will remain if there is no documentation. You need to have a keen eye to spot scars or bruises on darker skin.
Description of lesions needs to be metric and repeatable, there is no reason to not take a photo of a difficult to describe lesion. (although now there are issues with tampering of photos with programmes such as photoshop). If you take a picture, place a ruler in the periphery of the lesion at the same level of the lesion and consider putting a coin in the photo to help spot distortion or modification of the image later (make sure you take the picture perpendicular to the skin surface and the macro function on the camera will help). Remember you may need to share this information later with someone who didn't attend the visit, so they need to understand the lesion exactly as if they were there just from your description.
"...which criminal matters and medical negligence are key examples. In both cases the medical practitioner’s records will be scrutinized by a number of lay persons and medical and legal professionals, and failure to have kept appropriate records can lead to criticism of a practitioner’s competence, or fitness to practice. It is therefore in the interest of every medical professional to take great care in the contemporaneous documenting and recording of notes." Encyclopedia of Forensic Medicine 2005
How do you describe a lesion?
- Body district (area of body affected
- Type of lesion
- Colour
- Edges/limits
- Shape (geometrical shape)
- Orientation (longitudinal, transversal, oblique)
- Size
(More concise list of the possible characteristics you may need to record in describing a lesion, note that tenderness may be the only documented evidence of an injury)
In the physical assessment you may find actual lesions such as bruises, excoriations, lacerations or sharp force wounds or you may find evidence of past wound such as scars (note many cases of assault are reported weeks after the event). Assess with the best possible lighting and make sure you record everything clearly and concisely. You should be careful when labelling a lesions as a 'wound' or 'injury', 'wound' in some jurisdictions in the UK can imply the breaking of the skin, therefore its wise to be aware of the definitions in your local jurisdiction.
Types of lesions:
"The purpose of assessment and documentation of injury is, as far as possible, to define the type of injury caused, to assist in establishing how such a wound or injury was caused, and to determine how consistent the varying accounts of causation are with those that may have been given." Encyclopedia of Forensic Medicine 2005The account of the victim has to be recorded in meticulous detail, the weapon used (baseball bat, knive, hammer), the clothes worn, specific times and the handedness of the assaulter even. Assessment of the state of intoxication of the victim is also important as well as the state of the victim at the time of injury. Make sure you obtain consent for any pictures you take and the entire exam. Lastly after appropriate documentation, ensure that appropriate treatment or investigations is undertaken, after all he or she is your patient!
(Examples of points that may be relevant in the history)
Blunt force trauma
Sharp force trauma
Gun shot wounds
Asphyxia
Thermal injuries
Poisoning
Blunt force trauma
- Excoriations
- Bruising
- Lacerations
You can tell on a cadaver if the blunt force was performed when the cadaver was alive or dead by looking at histology. On histology, live tissue injury will show an inflammatory reaction with extravasation of red blood cells into the tissue. On dead tissue there is no inflammatory reaction, you can also use immunohistochemistry to spot the presence of cytokines and see if there are inflammatory cells present.
Remember to consider the anatomy of the area affected, some areas of the body contain abundant subcutaneous fat while others are located over bony prominences altering the effect the injury on the skin surface. Some areas such as the abdomen contain vital organs that can be severely damaged while the skin surface is relatively unaltered after blunt force injury.
Excoriations
Excoriations are loss of the superficial layers of skin due to blunt force trauma (not an abrasion, an abrasion is loss of the superficial layers of the skin caused by an object with a sharp margin like a knife). Typically occurs when the angle of impact is at less than 90 degrees.
(Picture showing the loss of superficial layers of skin with a blunt force trauma, note the direction of the forc, red arrows)
Excoriations often reproduce the shape of the object that cause it.
Excoriations often reproduce the shape of the object that cause it.
Often the excoriation will heal with a scab and at this point it will become impossible to age the lesion. ED physicians may be the only people able to preserve material evidence of assault from the lesion. It’s easy, you simply swab the lesion for 30 seconds before cleaning the lesion (moisten the swab with sterile water or saline before), store the swab in a tamper proof container and dry or freeze it (you can later give it to the police if necessary). Often under the nails of victim there is often attacker DNA (there can even be attacker DNA on the surface of a bruise from punches etc).
With excoriations you can often tell in which direction the blunt injury was caused and this can help reconstruct the event. (yet another reason for a good description and often there is some material left on the lesion from whatever object was used to create the lesion).
Scratch marks are a very typical and specific form of excoriation. Triangular or droplike in shape. They contain a lot of information about the author of the lesion and genetic information. A tyre mark may be another kind of distinct lesion (often the actual lesion is caused by the negative pressure by the treads in the tyre not the actual tyre surface).
(a typical scratch mark)
Bruising
Bruising is a sign of direct contact with a blunt surface. Bruises are frequent in cases of child abuse. A bruise means the trauma was in that place, a hematoma is a collection of blood and the trauma causing the hematoma may be elsewhere on the body. When in doubt it is best to describe the lesion as a cutaneous discoloration.
Bruising is a sign of direct contact with a blunt surface. Bruises are frequent in cases of child abuse. A bruise means the trauma was in that place, a hematoma is a collection of blood and the trauma causing the hematoma may be elsewhere on the body. When in doubt it is best to describe the lesion as a cutaneous discoloration.
Great example; black eye can be caused by a direct trauma (punch to the face) forming a BRUISE or may be caused by a basilar fracture of the cranium creating the so called racoon eyes this is a HEMATOMA. They will look almost identical.
Note that MRI can be used to age and discover origin of a bruise/hematoma. Bruising may be difficult to spot for example of North African darker skin.
A bruise is different to a hematoma!
( bruise, note the appearance of multiple colours at the same time)
Bruises are closed lesions that show a distinct discoloration. The colour relates to the age of the lesion but also the size is important. You may have different colours at the edge compared to the centre of the lesion due to difference in breakdown. You need to assess them carefully. For example a patient with multiple small bruises of same colour you can hypothesise were all caused at the same time. One large bruise may be purple while a neighbouring small bruise caused at the same time may be yellow.
Colour therefore depends on physiology, depth of injury and size. (there is modification over time). Factors listed in the textbook are: depth of bleeding, amount of bleeding, environmental lighting and overlying skin colour.
A general estimation of bruise age with regards to time can be:
RED = less than 24 hours
PURPLE/BLUE = 4 or 6 days
GREEN = from 7 days onward
YELLOW = 2 weeks after trauma.
Remember not to confuse a bruise with a hematoma.
RED = less than 24 hours
PURPLE/BLUE = 4 or 6 days
GREEN = from 7 days onward
YELLOW = 2 weeks after trauma.
Remember not to confuse a bruise with a hematoma.
Hematoma = filling of blood into a virtual space
Bruise = forcing of blood into a tissue
Note that old people bruise very easily and may even bruise spontaneously and that colours may appear different in photographs depending on the lighting, filter etc.
Lacerations
Third kind of blunt injury is a laceration, skin splitting or tearing after blunt force injury. A laceration is simply a discontinuation of the skin, you can put the two skin edges together as normal and reconstruct the skin as there is no loss of substance. You have to describe the margins well. Big clues that the laceration was caused by a blunt force trauma and not a sharp force injury is irregular skin edges or frayed edges and bridges of tissue. You can look at the subcutaneous tissue and it will be irregular and not smooth with a blunt force trauma.
Osseous injuries
Technically osseous injuries constitute a fourth catergory of blunt force injury. However, it is almost impossible to document some fractures without the use of x-rays in a living person (on the contrary, it will be easy on x-ray, just make sure you remove the dura mater to view cranial fractures).
Technically osseous injuries constitute a fourth catergory of blunt force injury. However, it is almost impossible to document some fractures without the use of x-rays in a living person (on the contrary, it will be easy on x-ray, just make sure you remove the dura mater to view cranial fractures).
Sharp force trauma
- Penetrating injury
- Cut marks
- Stab wounds and mixed injuries
"Sharp-force injuries are those injuries by any weapon or implement with cutting edges or points (e.g., knives, scissors, glass). The injuries may be classified into either incised (cut marks), where the cutting edge runs tangentially to the skin surface, cutting through skin and deeper anatomical structures, or stab (penetrating), where the sharp edge penetrates the skin into deeper structures. An incised wound is generally longer than it is deep, whereas a stab wound is deeper than it is wide." Encyclopedia of Forensic Medicine 2005Penetrating injury
Depending on the book you use, pointed objects may or not be included in this category. A very distinct lesion to look for is needle tracks or syringe wounds. Always look for syringe marks in any unconscious patient, observe the whole skin surface, needles may be injected behind the ear or even on the genitals.
The shape of penetrating object lesions can tell you the shape of the object tip used to cause the lesion. The flaps of the skin lesions will match the penetrating object tip for example a squared end will cause an X shaped flap, a triangular tip will cause a Mercedes sign skin flap and a circular point a circular lesion.
An example is a penetrating injury to the cranium, surgeons keep the piece of cranial bone with the penetrating injury, the shape of the hole in the bone can tell you what kind of object caused the injury.
Cut marks
Cut marks are caused by a sharp edge weapon and cause a neat discontinuation of the skin edge and tissue. The cut mark usually has a tail at the edge of the skin discontinuation and this can give you a lot of information about where pressure was least and hence in what direction the cut was performed (obviously this depends on the curvature of the skin area and the object used, its still difficult to tell entry and exit point). Remember not to confuse lacerations and cuts in your descriptions, this is the most common mistake made by nonforensic doctors.
Lesions on the neck or wrists are common in suicide attempts, look for 'tentative' or 'hesitation' wounds which are strongly indicative of self-infliction or previous scars.
Lesions on the neck or wrists are common in suicide attempts, look for 'tentative' or 'hesitation' wounds which are strongly indicative of self-infliction or previous scars.
Stab wounds and mixed injuries
Mixed weapons can give you stab wounds. These are weapons that can stab and can also cut. The cut mark is the result of passing the sharp edge and the penetrating injury the result of the pointed edge. Stab wounds contain a lot of information and will often reproduce the cross section of the blade. For example a double edged blade will produce a wound with two acute ends, a single edged blade will produce a wound with a single acute angled corner and an obtuse angled corner ('fishtail' wound). Sometimes the going in wound will not match well the going out wound and stab wounds may crossover each other making the lesion more complex and difficult to describe.
Remember that on skin and bones you may have residues of the instruments used to cause the lesions and you should always keep any debrided material.
Some mixed weapons form so called 'chop' wounds displaying features of both blunt force and sharp force injury, typical of heavy sharp weapons like an axe. You may see a surrounding bruise due to the hilt of the weapon used as well.
1. the direction of impact on to the body
2. the depth of an injury resulting from stabbing
3. the force used to inflict the injury, taking into account the various structures injured
4. injured structures and their bearing on morbidity and mortality
5. in cases of multiple stabbing, to assess which surface wounds are responsible for which internal injuries.
Some mixed weapons form so called 'chop' wounds displaying features of both blunt force and sharp force injury, typical of heavy sharp weapons like an axe. You may see a surrounding bruise due to the hilt of the weapon used as well.
"In the living victim, treatment within hospital may not properly document the size of wound prior to exploration or closure, or the depth of wound following exploration such as laparotomy or thoracotomy. Interpretation of such injury can become difficult.....Such issues become very relevant in court cases where a charge of attempted murder may be argued on the perceived depth of penetration of a knife (and by inference the force used to create the wound). It is in situations such as this that proper documentation of injury, pretreatment, within the nonforensic primary care and trauma settings, can be extremely helpful." Encyclopedia of Forensic Medicine 2005Ideally the following factors should be determined or commented upon in your report:
1. the direction of impact on to the body
2. the depth of an injury resulting from stabbing
3. the force used to inflict the injury, taking into account the various structures injured
4. injured structures and their bearing on morbidity and mortality
5. in cases of multiple stabbing, to assess which surface wounds are responsible for which internal injuries.
Gun shot wounds (GSWs)
See post on gun shot wounds...
Asphyxia
Asphyxia is the mechanical obstacle to penetration of air in to the airways. It is a manner of death or disease that leaves distinct signs depending on the method of asphyxia, the main types of asphyxia are:
- Smothering
- Choking
- Manual strangulation
- Ligature strangulation
- Hanging
- Drowning
- Traumatic (compression) asphyxia
- Plastic bag suffication
Unfortunately due to frequency of plastic bag suffocations in forensic pathology it has managed to deserve its own type of asphyxia.
With asphyxia there are many different types lesions that can be seen on the cadaver such as wide and large spread hypostasis, quicker putrefaction, early rigor, delayed body cooling, darker and more fluid blood, visceral congestion however, only one type of lesion is found on living bodies, petechiae!
Petechiae (pointiform bruising) is a very distinct sign of asphyxia and is caused by high pressure in the capillaries causing them to burst. Not always seen, it can be subtle, for example on the conjunctiva it is a common sign with strangulation.
Smothering is a good way to get away with murder there is often no sign apart from petechiae. There may be scratch marks, compression marks from teeth inside the lips or fibres from the object (usually a pillow). Smothering is occlusion of the outer opening of airways while choking is the occlusion of the inner airways.
Choking is usually accidental often people with neurologic or psychiatric disease or issues with the swallowing reflex.
Strangulation is a mechanism of death and not necessarily the lack of air. The death can be caused by nervous factors such as compression of the glomus body of the carotid artery and reflexive cardiac arrest. There are many anecdotal deaths where an aggressive attacker grabs an old man by the neck and he just drops dead almost instantly (the attacker will be mentioning in court how he hardly touched him). You usually see bruising with compression of the airways. Fracture of the hyoid or cricothyroid cartilage can have a distinct pattern with strangulation too. (note that the hyoid bone fuses very late in development, can be rare to see bilateral fusion of the hyoid bone in the 20s). A ligature strangulation will often have a linear bruise of uniform depth sometimes with fibres still around the area (eg. rope burn). The four features of a ligature strangulation wound are; transversal, same depth, continuous, multiple.
With hanging there are often distinct fractures and ligature signs. You can tell easily if the person was hung before or after death by again looking at the haemorrhaging in the neck and the presence of an inflammatory response which is lacking with a dead body.
Traumatic asphyxia is caused by a heavy object compressing the rib cage restricting breathing.
Drowning is an awful way to die, often taking longer than 6 minutes as you alternate between periods of consciousness and unconsciousness. An important note is that water in the lungs is not proof of drowning! There is often water in the lungs in cadavers and it may have many origins (although sometimes it can be obvious with the post autopsy lung able to stand by itself it’s so full of water). Often the only proof of drowning is the presence of diatoms (microscopic algae) in the blood and organs (the diatoms being distinct to the body of water where the drowning occurred). When you drown the alveoli burst and water mixes with the blood providing an entry point for diatoms to enter the blood. A long period after drowning there may be characteristic skin wrinkling and pink discoloration (pink teeth) but this is more for shipwreck victims for example.
Thermal injuries, a common form of abuse. (see post on burns)
Cigarette burns- full thickness, forming a crater, rule out impetigo and chicken pox.
Cigarette burns- full thickness, forming a crater, rule out impetigo and chicken pox.
Poisoning
A poison is any element or chemical substance which when introduced into the body acts through a biochemical method to provoke disease or death, dose independently.
A poison is any element or chemical substance which when introduced into the body acts through a biochemical method to provoke disease or death, dose independently.
History is so important! Diagnosis of poisoning will require; anecdotal evidence, autopsy and clinical toxicology. If suspected keep a sample of blood/urine for a specific toxicology test that may be needed later. Many poisons are not included in the general toxicology screen performed in most ER’s. Also consider keeping a small lock of hair (from the roots), with this you can prove that the drug was not present in the victims system at time zero.
Short note on defensive wounds
Some lesions are characteristic of the victim defending himself/herself during an assault. Lesions on the extensor surface of the forearm, lateral/posterior upper arm or dorsum of hands are classic of defence to blunt or sharp objects (victims naturally protect their face by raising their arms up). Another natural reaction to sharp force is to grab the blade causing cuts/incisions to the palmar surface of the hand.
SOURCES:
Vij K, Forensic Medicine and Toxicology, 5th edition, 2011
Payne-James J, Byard R, Corey T, Encyclopedia of Forensic Medicine, 1st edition, 2005
Hobbs CJ, Hanks HGI, Wynne JM, Child abuse and neglect: a clinician’s handbook, II Ed., Churchill-Livingstone, London, 1999
Hughes VK, Ellis PS, Langlois NEI, The perception of yellow in bruises, J Clin Forensic Med 2004;11:257-9
Short note on defensive wounds
Some lesions are characteristic of the victim defending himself/herself during an assault. Lesions on the extensor surface of the forearm, lateral/posterior upper arm or dorsum of hands are classic of defence to blunt or sharp objects (victims naturally protect their face by raising their arms up). Another natural reaction to sharp force is to grab the blade causing cuts/incisions to the palmar surface of the hand.
SOURCES:
Vij K, Forensic Medicine and Toxicology, 5th edition, 2011
Payne-James J, Byard R, Corey T, Encyclopedia of Forensic Medicine, 1st edition, 2005
Hobbs CJ, Hanks HGI, Wynne JM, Child abuse and neglect: a clinician’s handbook, II Ed., Churchill-Livingstone, London, 1999
Hughes VK, Ellis PS, Langlois NEI, The perception of yellow in bruises, J Clin Forensic Med 2004;11:257-9
Lectures on forensic medicine Univerista Degli Studi Di Milano.
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