Tag Archives: Penetrating trauma

Pop Quiz! The Case, Part 2

Yesterday I presented the case of a young man who shows up at the triage desk in your ED with “something wrong with his head.” I showed an AP skull film, which shows some kind of metallic foreign object. What is it? Where is it? What to do?

First, look at the image carefully. The object is metallic density and appears very thin. But remember, any diagnostic image you view is a 2D representation of a 3D space. You have no idea of the orientation of the object, or exactly where (front to back) it is located. He could be lying on top of it, or it could be stuck in his brain.

At the far left side of the image, the thin metal appears to get even thinner. Dead giveaway! Look at the diagram below.

The knife tang is the thin part of a knife that the handle is fastened to. @andrewjtagg tweeted that he wouldn’t mind seeing a lateral, so here it is.

Yes, it’s a knife. A steak knife to be exact. Somewhere in the middle of the face.

First off, you didn’t need to see these to start doing the right things. Since this is a penetrating injury to the “head, neck or torso” it should trigger any trauma center’s highest level of activation. He is whisked off to the trauma bay and quickly evaluated. He’s obviously awake and alert (he walked in), so what do you need to treat him, and how would you manage it?

Tweet or leave comments. More discussion (and pictures) on Monday.

Best Of: 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.

ImportantThis 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 mark? 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. In this example, the blade is angling upward toward the right.

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.

AAST 2011: CT Evaluation of Penetrating Neck Trauma

In the old days, stab injuries to Zone 2 in the neck meant a trip to the operating room. Then it became acceptable to evaluate stable patients with this injury via endoscopy, angiography and a swallow study. Most chief residents didn’t have the patience for this and opted for OR anyway. CT now promises to simplify the evaluation process, rolling these studies into one fast and simple one.

USC+LAC and the University of Maryland directed a prospective multicenter study that looked at the sensitivity and specificity of using CT angiography of the neck to evaluate penetrating injuries.All patients underwent a structured physical examination of the neck. If hard signs of injury to the vascular tree or aerodigestive tract were present, they were immediately taken to OR (6%). Nearly all of these patients had an injury that required repair. If they had no signs, they were merely observed (51%). None had a missed injury.

The remaining 159 patients had a positive exam (minor oozing, small stable hematoma) underwent CT angio of the neck (54% stabs, 42% gunshots, 4% other). The majority were in Zone 2 (41%), but 24% were in Zone 3, 21% in Zone 1, and 14% crossed multiple zones. Overall sensitivity was 100% and specificity was 97%. CT angio was nondiagnostic in 3 patients due to missile fragment artifact.

Bottom line: CT angio of the neck is a fast and accurate exam that can be used in stable patients with an abnormal physical exam but no hard signs of injury. This fits my bias, and we have already been using the scanner this way for stabs. I would now recommend cautiously extending its use for select gunshots as well.

Hard signs of neck injury:

  • Unstable vital signs
  • Large, expanding, or pulsatile hematoma
  • Active bleeding
  • Air bubbling
  • Voice or airway disturbance
  • Hematemesis / hemoptysis
  • Thrill / bruit
  • Neurologic deficit

Reference: Evaluation of multidetector computed tomography for penetrating neck injury: a prospective multicenter study. AAST 2011 Annual Meeting, Oral Paper 61.

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.

How Big Was The Knife?

As part of a thorough history and physical on any trauma patient, we typically ask “How big was the knife you were stabbed with?” and “How deep did it go?”

Unfortunately, the answers you typically will get are “This big!” while they hold their hands at least 3 feet apart, and “All the way, doc!”

These answers are not very helpful, so it is not really of much use to ask the questions. The “how big” question is not helpful at all, because a long knife may barely penetrate, and a paring knife can make it all the way into the heart.

This leaves the “how deep” question. There are two ways to determine the answer. If the paramedics or police bring the weapon in, you can carefully examine it (taking proper care to preserve forensic evidence) and see if there is a blood line extending from the tip. This will show the maximum depth of penetration.

The second way is to examine the wound, either by local wound exploration or using CT.

Helpful hint: You can’t tell how large (wide) the blade is by looking at the wound. The elastic nature of the skin causes it to stretch as it is being cut during the stab. When the knife is removed, the resulting laceration will always be less wide than the blade.