24.6.2010 GUNSHOT WOUNDS

I never thought much about gunshot wounds before today, I suppose I never really needed to.
But after I had encountered a lady who was shot in the right side of her abdomen at close range and remained pretty much unscathed, because the bullet routed itself through her womanly 'muffin' abdominal excess and came out the other side, leaving the intra-abdominal cavity untouched, I was just very intrigued by the effect of the bullet on human tissue.
After a spot of reading around the subject, I discovered, that an entrance wound, would characteristically leave soot on the outside skin or lacerate the skin from the gas effects (exception is when an airgun is used!). The closer the range shot, the more soot stippling on skin. Distance shots tend to lack the soot component but will exhibit a hole that approximately equates to the calibre of the bullet fired.
When the bullet is in, the injury sustained depends on a number of factors - bullet deformation, bullet fragmentation, characteristics of the bodily tissue impacted on.
Relative density (mass/volume) is vital to understanding tissue damage, the greater the density the greater the damage. Whereas, elasticity reduces the level of damage. So we can then see why lung tissue with a low density and high elasticity would be damaged far less than muscle, and even more less than organs like the liver, spleen, brain. Bone, has a more dramatic effect of causing fragmentation of both the bone and bullet, which goes on to do collateral damage and make the hole much larger too. Then we have fluid filled organs, which just explode and release their contents, which itself can be even more problematic.
The bullet itself may vary in its quality and ability to execute damage, a hollow point bullet will actually give you an increase in volume of disrupted tissue and fragmentation, without giving you an exit wound. A fully coated metal bullet will give you an exit wound, but these may also recoil off bone.
My patients bullet did exit out very neatly, however most bullets are designed not too exit (then they do more damage of course). If you were try and distinguish between exit and entrance wounds, you would note the exit wound is larger, as the bullet has expanded or deviated from its initial alignment. There may also be less gunshot residue. You might also need to bear in mind there may be more than one exit wound (fragmentation of the bullet resulting in secondary missiles ) and the exiting bullet will necessarily come out at the opposite end to the entrance, as the bullet is unlikely to make a linear track out. The bullet track can be influenced by the targets position, so the organs affected on the sitting target will alter from that of the standing targets.
This patient, was extremely lucky, she got away fairly intact despite a close range bullet shot, a few sutures at the entrance and exit wounds, were the (physical) remnants of her encounter with a bullet.
And me, I feel I have acquainted myself very well to bullet trajectory and if I dwell any further it wouldn't provide anyone with any additional benefit and I might be labelled as slightly fanatic :)