The Ins and Outs of Gunshot Wounds

In the United States, victims of gunshot wounds represent a significant majority of all homicides (and a high proportion of suicides). There’s a propensity among other medical specialties to think of forensic pathologists as “bullet pullers,” just collecting the used projectiles and moving on to the next case. However, autopsies of multiple gunshot wound victims can be some of the most detailed examinations we perform. Even though the cause of death isn’t a mystery, thorough observation and documentation is crucial for other questions which may arise – was the victim immediately incapacitated? Did the shooter reload during the assault? How close to the victim were the shots fired? To address these questions, it’s first helpful to understand the basics of gunshot wounds.

Gunshot wounds can be penetrating (entering the body without exiting) or perforating (entering and exiting the body). Full body x-rays are taken in all gunshot wounds to identify retained projectiles, all of which must be recovered as evidence. It’s important to not use metal tools (like forceps or scissors) when removing a projectile, which may scratch metal and interfere with ballistics comparison.

Under typical circumstances, distinguishing entrance from exit wounds is straightforward. Classic entrance wounds are circular, as the bullet hasn’t yet been deformed, and there is a surrounding rim of abrasion where the edges of the bullet scrape against the skin. In contrast, exit wounds have a stellate or slit-like appearance, but the wound edges can typically be reassembled and are not abraded. As with any area of medicine, though, real life doesn’t always follow the rules. An entrance wound can be atypical if the bullet has passed through an ‘intermediary target’ before striking the victim (say a piece of furniture or a car door). If the area of exit is pressed against a firm object (even a tight pants waistband), the skin edges will be abraded (or “shored”). Sometimes, the entrance and exit truly cannot be distinguished – this is more likely with superimposed decomposition, insect activity, or superficial wounds.

Range of fire is another important feature to note and is the reason we always take photographs of a wound before cleaning the body. When a gun is fired, smoke, soot, and unburnt particles of gunpowder exit the barrel as well as the bullet. The smoke creates “fouling,” dark discoloration which easily wipes away and can be seen if the end of the barrel is within approximately one foot of the victim. Stippling, caused by unburnt grains of gunpowder, are actual abrasions and can be seen when the projectile fired within 18” of the victim. These are gross generalizations, though, and in each individual circumstance the weapon itself must be tested to identify the distances. If soot or gunpowder particles aren’t visible on the skin surface, they may have been deposited on the victim’s clothing. ‘‘Bullet wipe’ is slightly different from fouling, in that it is dirt and residue on the actual bullet which gets ‘wiped’ off around the entrance wound on clothing – so it doesn’t tell you range of fire, but it can be helpful to identify tricky entrance wounds.

Now, for some of the common misconceptions around gunshot wounds …

Can you tell the caliber of the gun from the size of the wound? The answer is an emphatic “no.” Much of the injury caused by a bullet comes from the temporary wound cavity created by dissipation of kinetic energy; so no matter the size of the bullet, tissue will stretch and distort around it.

Can you tell the order in which gunshot wounds were sustained? Most often, no. In some autopsies, the first wounds cause so much blood loss that the later wounds lack hemorrhage, but this is the exception rather than the rule.

Can I tell what position the victim was in when they were shot? Again, usually not. In isolation, an autopsy can only tell you the trajectory of the bullet through the body; to determine the position of the victim when they were shot requires knowledge of either where the gun was when it was fired or where the bullet landed–two factors which are often not available.

These are just a few of the complexities faced by a pathologist when working with gunshot wounds, and we haven’t even covered different types of ammunition or firearms. Stay tuned for more in the future!

This is an example of a classic entrance gunshot wound – nearly circular, with a thin rim of abraded (or scraped) skin.
In contrast, this exit wound is slit shaped, and the wound edges can be neatly reapproximated.
This entrance wound has stippling on the surrounding skin; occasionally gunpowder particles are still visible embedded in the abrasions.

-Alison Krywanczyk, MD, FASCP, is currently a Deputy Medical Examiner at the Cuyahoga County Medical Examiner’s Office.

“CHiPs” and Dips

A delivery truck is backing up to the loading dock of an empty warehouse. You are about to receive the first ever delivery from your supplier, and soon this new lab will be up and running. Are you going to unload the truck and stash the new chemicals in the corner? I hope not. Getting started with chemical management can be a little overwhelming, but it certainly can be done. Benjamin Franklin said, “By failing to prepare, you are preparing to fail.” It is best to start with a plan, preferably a chemical hygiene plan (CHP). So, let’s take a dip into a few important sections of the CHP.

The creation of a great CHP begins by listing the chemicals you have onsite and their associated hazards, and this will be your chemical inventory. Categorizing your chemicals by hazard type helps you to determine where and how they should be stored and handled once in the lab. It’s important to determine the compatibility of your chemicals before you place them on the shelves. Storing your inventory in alphabetical order may make it easier for staff to locate a particular item, but not all chemicals play nice with each other when they are neighbors. A bottle of chloric acid stored next to calcium hydroxide could be an accident waiting to happen. Make sure incompatible chemicals are kept apart, stored on separate shelves, or kept in separate bins. Do you store ethanol onsite? What about xylene? Both are flammable chemicals, so you may be able to store them in the same flammable safety cabinet. Separate corrosive storage cabinets may also be needed for your strong acids and bases.

Now that we have the chemicals separated, what do you do when it is time to use them? Your CHP should outline training and personal protective equipment (PPE) requirements for the different hazards as well as any engineering controls required to ensure work can be performed safely. Do you have a biological safety cabinet (BSC) in your lab? Be careful, not all BSCs can or should be used as a chemical fume hood (CFH). A CFH is designed with specialized filters and/or ducting to eliminate hazardous vapors that BSCs lack. Only a few classes of BSCs can provide protection from volatile chemical fumes. Check with the manufacturer to determine if it is safe to handle volatile chemicals in your BSC.

Next, you decide how you are going to dispose of the chemical waste you may generate in the lab. Never assume that liquid chemical waste is allowed to be poured down the drain. Some acids and bases that are poured down the drain will alter the pH of your wastewater. The Environmental Protection Agency (EPA) and the local wastewater authority will not be fans of that practice. Hazardous waste disposal requirements vary from state-to-state, so be sure to know the laws in your area for your place of business (see website: EPA Hazardous Waste Programs).

So now your chemicals stored properly, you know how to use them safely, but what is the plan when something unexpected happens? The accidental release of chemicals can be quite dangerous, and so can a poor response. A well written spill response procedure and periodic training can make clean-up a much less risky operation. The first and most important step is to correctly identify the chemical that spilled. Make sure staff know the location of your Safety Data Sheets (SDS), know how to access them, and that they are up to date. You may use an online database to access the SDS, and some services will even automatically update the SDSs to ensure you are viewing the most current version.

Make sure there is a spill kit in the lab that can effectively handle the accidental release of the different types of hazardous materials in your area. The kit should include the materials for a biohazardous spill as well. Ensure you have a well written procedure that describes the steps to safely and effectively clean up the spill. Your procedure should outline actions such as securing and surveying the site, donning the required PPE, laying down barriers to prevent spreading, and applying absorbents. Also include information about extraction of the clean-up material and proper disposal. Remember, the waste created from a chemical spill is considered a hazardous waste and must be treated as such. Absorbed chemical waste should be placed in a bag specially designated for hazardous waste (and segregated for offsite removal by your waste vendor.

The drafting of a CHP does take time and attention, but you cannot stop there. Your CHP is a living document that requires attention, and once it is created, you never want to let it go stale. It is important to keep your CHP fresh by updating it often. In fact, OSHA and most accrediting agencies require laboratories to review their CHP annually and assess its effectiveness. Keep staff knowledge about your CHP crisp. When staff know how to locate and use their CHP, they are more prepared to work safely with hazardous materials.

-Jason P. Nagy, PhD, MLS(ASCP)CM is a Lab Safety Coordinator for Sentara Healthcare, a hospital system with laboratories throughout Virginia and North Carolina. He is an experienced Technical Specialist with a background in biotechnology, molecular biology, clinical labs, and most recently, a focus in laboratory safety.