How To Read A Stab Wound

Most emergency departments do not see much penetrating trauma. But it is helpful to be able to learn as much as possible from the appearance of these piercing injuries when you do see them. This post will describe the basics of reading stab wounds.

Important: This information will allow some basic interpretation of wounds. It will not qualify you as a forensics expert by any means. I do not recommend that you document any of this information in the medical record unless you have specific forensic training. You should only write things like “a wound was noted in the midepigastrium that is 2 cm in length.” Your note can and will be used in a court of law, and if you are wrong there can be significant consequences for the plaintiff or the defendant. This information is for your edification only.

1. What is the length of the wound? This does not necessarily correspond to the width of the blade. Skin stretches as it is cut, so the wound will usually retract to a length that is shorter than the full width of the blade.

2. Is the item sharp on one side or both? This can usually be determined by the appearance of the wound. A linear wound with two sharp ends is generally a two sided knife. A wound with one flat end and one sharp end is usually from a one-sided weapon. The picture below shows a knife wound with one sharp side.

Single edge knife wound

3. Is there a hilt? This can usually be detected by looking for bruising around the wound. The picture below shows a knife wound with a hilt mark.

Knife wound with hilt mark

4. What is the angle? If both edges are symmetric, the knife went straight in. If one surface has a tangential appearance, then the knife was angled toward that side. You can approximate the direction of entry by looking at the tangential surface of the wound edge.

Angled knife entry

5. How deep did it go? You have no way of knowing unless you have the blood stained blade in your possession. And yes, it is possible for the wound to go deeper than the length of the knife, since the abdominal wall or other soft tissues can be pushed inwards during the stab.

Seatbelt Use By Trauma Professionals

Every trauma professional knows that seat belts save lives. Numerous studies have borne out the survival benefits of wearing them. But do those same professionals practice what they preach?

A recent study by NHTSA study showed that at least 42% of police officers killed in car crashes were not wearing their seat belts. The number of officers killed in traffic accidents in 2010 has increased by 43% over 2009 numbers. Possible reasons may be that seat belts impede the process of getting into and out of the car quickly, and that the belt may get tangled in utility and gun belts.

What about paramedics and EMTs? I couldn’t find any studies looking at this group. However, observation tells me that medics in the patient care compartment don’t always buckle up. The reason typically given is that wearing a belt may compromise patient care by limiting access to equipment, using the radio, or performing CPR. However, I think that patient care is even more limited if the EMS professional is disabled or killed in a rig crash. The patient is much more likely to survive such a crash since they are firmly strapped into place.

How can you stay safe in the back?

  • Make a commitment to your colleagues (and family) to always belt in
  • If appropriate, try to do as much of your assessment and interventions as possible before moving
  • Organize your work area so that commonly used and critical equipment is within easy reach
  • Use a cell phone for communication if the radio mic is too far away
  • If you absolutely do need to unbelt, try to do so only when the rig is stopped at a light or stop sign.

I’m interested in your comments about how common of a problem this really is. Unfortunately, I don’t think NHTSA will be doing any studies on this one.

Less Morbidity From Negative Trauma Laparotomies?

Trauma surgeons generally dread the negative laparotomy for trauma. Previous work has shown that complications occur in anywhere from 22% to 53% of cases. Those studies were usually retrospective and included patients with penetrating trauma, which may have skewed the results.

A newly published study tries to throw this common wisdom in doubt. It was a retrospective review of a prospectively maintained database of trauma admissions after blunt trauma . Patients were separated into groups who underwent immediate, delayed or no laparotomy, as well as whether they had or did not have associated injuries. Complications were tracked using an accurate and validated tracking system. The complications tracked included death, DVT, PE, infections, pulmonary issues, as well as other organ system problems.

The authors found that a negative laparotomy did not increase the complication rate, but that a delayed laparotomy did. They also noted that a Complication Impact Score (that they made up) was higher in the delay to laparotomy patients. So they believe that when clinical and imaging findings are equivocal, doing an operation to establish a diagnosis is justifiable.

My Bottom Line: This study does not look at really delayed complications like small bowel obstruction, which we see with some regularity in old trauma patients. Also, other studies have also shown that brief observation, even in patients with a bowel injury, does not increase complications significantly. Unless the potential injury that you are observing is known to have significant complications, my practice is to observe equivocal cases in order to avoid more complications down the road.

Reference: “Never be wrong”: the morbidity of negative and delayed laparotomies after blunt trauma. J Trauma 69(6): 1386-1392, 2010.