Tag Archives: stab

Retained Foreign Objects After Penetrating Injury

A Chinese man was in the news a few years back after having a four inch knife blade removed from his head. It had been there for four years!  The knife blade broke off after he had been stabbed under the chin. Unfortunately, he was unaware that any part of the knife had been retained. It remained partly within the nasopharynx and the tip came to rest behind his left eye. His symptoms included headaches, stuffy nose and bad breath. The picture below shows the badly corroded blade in front of some of his radiographic images.

See the video at the bottom of this post for more details and images.


What is the best way to deal with a problem like this? Here are some practical tips:

First, get in the habit of imaging any body part with a penetrating injury. Retained objects can be as simple as gravel or as complicated as the knife blade above. And remember, some patients who have been stabbed present with a simple laceration but don’t want to tell you how they got it. Image before you close it!

Next, don’t remove it. This is common knowledge, but innocent looking objects (pencils, nails) can penetrate arteries and keep them from bleeding while embedded. Unpleasant and sometimes fatal bleeding can ensue if pulled out.

If you do not have specialists versed in the body regions involved in the injury, transfer immediately with the object secured in place. For objects penetrating minimally complex areas like the extremities, surgeons may opt to carefully remove it in the emergency department, or may elect to do so in the operating room.

Injuries to complex areas should undergo high resolution CT scanning so that 3D reconstruction can be performed if needed. The surgical specialists can then plan the operative approach. This is dictated by the anatomy of the area(s) involved and the architecture of the object (think about hooks and barbs). For objects located near critical areas, an operative exposure must be selected that provides access to all portions of it, and allows for rapid vascular control if needed.

Penetrating Injuries to the Extremities

Simple penetrating injuries to the arms and legs are often over-treated with invasive testing and admission for observation. Frequently, these injuries can be rapidly evaluated and disposed of using physical examination skills alone.

Stabs and low velocity gunshots (no rifles or shotguns, please) should be thoroughly examined. This includes an examination of the entire, unclothed body. If this is not carried out, there is a risk that additional penetrating injuries may be missed.

For gunshots, look at the wounds and the estimated trajectory to try to demonstrate that the object stayed clear of neurovascular structures. This exam is imprecise, and must be accompanied by a full neurovascular exam and evaluation of the bones and joints. If there is any doubt regarding bony involvement, plain radiographs with entry markers should be performed. Any abnormal findings will require more in-depth evaluation and inpatient admission.

If the exam is negative but the trajectory is “in proximity” to a major vessel, an arterial pressure index (API) should be measured. This test involves the calculation of the ratio of the systolic pressure in the injured extremity to the contralateral uninjured extremity. It should not be confused with the ankle brachial index (ABI) which compares the systolic pressure in the ipsilateral uninjured arm  or leg.

The magic ratio is 0.9. If the API is less than this, there is some likelihood that a vascular injury is present. If the API is higher, there is virtually no chance of injury.

The final test that must be performed before discharge is a function test. If the injured extremity is too painful to use or walk on, the patient may need to be admitted for pain management and therapy. Patients managed in this way can avoid arteriography, CT angiography or admission and save thousands of dollars in hospital charges.

Reference: Journal Am Coll Surgeons 2009;209:740-5.

How Good Is The Spine Exam In Penetrating Injury?

Examination of the spine in trauma patients is typically not very helpful. We always look for stepoffs. swelling and tenderness, but the correlation with actual injury is poor. A recent paper presented at the American Medical Student Association Annual Convention showed that it actually can be helpful in victims of penetrating injury.

A prospective study of 282 patients was carried out at a Level I Trauma Center, specifically focusing on penetrating trauma. Half had gunshot wounds, and 8% sustained spinal injury with one third left with permanent disability. Stab wounds never led to a spinal cord injury. The most common patterns for cord injury in gunshot wounds was a single shot to the head or neck, or multiple shots to the torso.

The examiners looked for pain, tenderness, deformity and neurologic deficit. They found that the sensitivity was 67%, the specificity was 90%, the positive predictive value was 95% and the negative predictive value was 46%. These numbers are much better than those found during spine examination after blunt trauma. They also determined that prehospital immobilization after penetrating injury would not have helped, which I have also written about here.

Bottom line: A good spine exam in victims of penetrating trauma can accelerate definitive management prior to defining the exact details of the injury with radiographic or MRI imaging. This is particularly helpful in patients who present to non-trauma centers, where imaging or image interpretation may not be readily available.

Reference: American Medical Student Association (AMSA) 60th Annual Convention: Abstract 26: Presented March 11, 2010

Knife To The Back! Part 2

Yesterday, I presented a case of a young man with a knife in his back. He was brought to your ED in the prone position. The question was, what to do next?

With any trauma patient, regardless of size, shape, or position, the first question is always, “does this patient belong in the ED?” And usually, that question is answered by checking hemodynamic stability.

This patient stays prone while you quickly assess vital signs. If vitals are abnormal, he needs to get rolled to the operating room immediately, while still prone. There is no time to figure out how to reposition, or if the knife can be removed. Get him out of your ED.

But let’s say he is hemodynamically normal and talking to you. You need more information. So start with a physical exam. With him in the prone position! It works. In this case, there are no other puncture wounds, and the anterior part of the body can be examined by carefully logrolling him onto his side. Breath sounds are decreased over the right chest, otherwise there are no other anomalies.

So now what? Well, let’s get some more info! How about a chest xray? Best position? Prone! It’s the easiest, because the patient does not need to be held up next to an xray plate, which would also have to be held manually. The lateral view doesn’t add anything but hassle. Here’s the result:

Now what? What do you see, what do you do? Tweet or comment; more to follow tomorrow.

Related post:

When Can You Close That Stab Wound?

I find that many trauma professionals are nervous about closing stab wounds. They seem to worry a lot about infections and lean toward leaving the wound open to heal by secondary intention. But is this warranted?

The answer is: probably not. Most knives used for assaults are clean, but not quite sterile. Yes, there are a few bacteria on the blade, but not very many. So if the usual wound management guidelines are followed, the patients generally do quite well. 

The guidelines are:

  • No gross contamination. If the knife was used to cut raw chicken or to stir up manure, that’s a problem. Leave it open.
  • No devitalized tissue. Complex lacerations with dusky skin bridges may get infected. Debride or leave open.
  • Don’t let the wound get fully colonized with skin bacteria. There is no good literature on this, but more than 12 hours for most of the body and 24 hours for the face is a reasonable guideline.

If any of these guidelines have been violated, it’s probably best to leave the wound open. Otherwise the default should be to try to close it as soon and as cleanly as possible. This means irrigating with saline to decrease any bacterial counts. Either sutures or staples are acceptable.

The most important part of this process is patient education. They must be informed about what signs of a wound infection to look for so they can return earlier rather than later to have you deal with it.

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