Part II - some terminology as applies to gunshot wounds
I must warn you that all the linked images are graphic.
I am seeing varied and confusing terminology when discussing the behaviour of a projectile when interacting with a target on this board. I thought I would describe the terminology I use as applies to gunshot wounds.
There are four possible outcomes when a projectile is fired at a person:
1) It can miss.
2) It can graze the person.
3) It can go into the person and not come out. The proper term for this is a penetrating injury.
4) It can go into the person and some or all of the original projectile can come out. The proper term for this is a perforating injury.
I am not concerned with number (1) above, I am only concerned with hits of some description. Likewise I am not concerned with intermediate targets, I am only concerned with the type of injury the projectile causes from the moment it hits the target.
Vincent Di Maio says that there are 4 types of gunshot wounds:
1) Graze
2) Tangential
3) Penetrating
4) Perforating
His description of a graze injury is the same as my description of a tangential injury. His description of a tangential injury is one where the skin is ripped in a ragged fashion and there is potential for underlying subcutaneous damage. The examples he offers in his book "Gunshot Wounds" are all due to high velocity projectiles from centerfire rifles. I would rather call those injuries perforating injuries because it is my opinion that those projectiles have breached the skin and that the rupture of the skin along the bullet track is not due to the direct passage of the projectile. The ragged nature of the breaches supports my observation (the tears look like lightning strikes).
Anyway the point I am making here is that I have a different view from Di Maio and I only describe three types of gunshot wounds:
1) Tangential
2) Penetrating
3) Perforating
Di Maio and I have the same description of what a penetrating and perforating wound is. I will provide graphics to demonstrate the 3 types as I describe them. Figure A is a tangential trajectory, Figure B is a penetrating trajectory and Figure C is a perforating trajectory.
The key features of a tangential gunshot injury are as follows:
1) It is a 'graze.'
2) The wound can be visually inspected. There is no damage that is not directly accessible by the health care worker.
3) No projectiles or fragments thereof are retained in the wound.
4) This is the only gunshot wound that does not merit being X-rayed. The reason it does not have to be X-rayed is because the clinician's visual inspection provides all the information he or she needs to assess the severity of the wound.
5) Generally the patient does not require hospitalisation. The only detrimental effects to look out for in these cases are those relating to infection and also those related to psychological stress on the victim.
Here is a typical tangential wound (Vincent Di Maio calls this a graze wound).
http://i55.photobucket.com/albums/g154/Odd_Job/Tangential.jpg
The key features of a penetrating gunshot injury are as follows:
1) All of the original components of the projectile that were incident to the skin, are retained in the body.
2) Whether the projectile fragments or deforms is irrelevant to the classification of this injury as 'penetrating.'
3) If the projectile or fragments thereof are propelled through the body by natural means and are subsequently expelled this remains a penetrating injury. There are many cases in the literature where this has happened. A typical example would be a projectile fragment that enters the urinary system and is subsequently expelled in the urine.
4) All penetrating gunshot injuries must be X-rayed because the clinician cannot visually inspect the wound track and therefore cannot give a 100% guarantee that all projectiles or fragments thereof have been accounted for.
Here is a typical penetrating gunshot wound (note that technically if you were dead certain that no other skin breaches were present, you could confidently call this an entrance wound):
http://i55.photobucket.com/albums/g154/Odd_Job/Penetrating.jpg
The key features of a perforating gunshot injury are:
1) All or part of the projectile that was incident to the skin travels subcutaneously and makes an exit from the body.
2) It does not matter whether the whole projectile exits or only a piece of the core, or only a piece of insert or only a piece of jacketing: this is still a perforating gunshot wound.
3) If a projectile breaks into two pieces and only one piece makes an exit, this is still a perforating wound. This classification is not affected by projectile fragments remaining in the body.
4) All perforating gunshot wounds must be X-rayed.
Here is a perforating gunshot injury:
http://i55.photobucket.com/albums/g154/Odd_Job/Perforating.jpg
Now there are several things I want to point out here. Firstly there are pitfalls surrounding the classification of a wound as perforating. The most problematic of these pitfalls is the tendency of some ER clinicians to count skin breaches and attempt to classify the wound in that manner. For example they will count two holes and assume that this is a perforating injury. However those two holes could easily be two entrance wounds from two penetrating injuries.
The next pitfall is the tendency of some ER clinicians to expect exit wounds to be larger than entrance wounds, and indeed, to classify wounds as being those of entrance or exit based purely on the size of the wounds or a general 'impression' of the wounds. There is adequate literature to indicate that clinicians generally do not accurately describe wounds of entrance and exit. I put this down to lack of experience or forensic training or lack of means and time to examine these wounds and arrive at a proper determination of whether these are entrance or exit wounds. My experience in a very busy trauma unit in Johannesburg leads me to make the following recommendations to ER staff:
1) Do not, in any written or verbal communication or documentation, make a statement to the effect that a particular wound is an entrance or exit wound, unless supplementary evidence not related to the appearance of the skin breaches themselves is at hand. In simple terms, don't declare it unless you have other proof such as X-ray imaging (radiology can determine which wound is the entrance and which one is the exit in some cases), or clothing evidence (a failed exit through the fabric means the corresponding skin breach is an exit wound in most cases).
2) Size doesn't matter. Granted, in most perforating injuries where the bullet has remained intact the exit wound will be larger because the bullet may have yawed or expanded prior to exit. However, don't forget what I said about perforating injuries: you need only have a portion of the original projectile making an exit in order for this to be a perforating injury. You can't be sure of which components have exited the body without having good knowledge of what the radiological appearances of a particular projectile are, coupled with knowledge of what projectile is involved in the case at hand.
3) The patient's recollection of events may not be accurate. There may be a nefarious rationale behind this. Asking how many shots were fired may not be helpful, depending on the circumstances of the shooting.
As I said previously you have less chance to make a mistake by finding a single skin breach and calling that the entrance wound as opposed to assuming that multiple breaches are due to a perforating injury.
When discussing other targets such as gel blocks, car doors, furniture etc I would use the same terminology. If a bullet penetrates a car door it means it went in one side and did not come out the other. If it went through the car door, then it perforated the car door. And then you have the added factor of tangential shots producing ricochets, but that is a subject for another thread.
I'm here mainly to talk meat, not metal
