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Quick Reference: Symptoms: Leg Gunshot Wounds : Emergency Medicine News

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gunshot wound, trauma, diagnosis

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A 50-year-old man was rushed to a Level I trauma center about an hour after being shot in the legs with a shotgun at close range.

He had normal vital signs on arrival and reported pain at the injury site. Numerous haemostatic penetrating wounds were observed throughout the front of his legs. The wounds extended from the ankles to the groin.

The tibial and dorsal pulses of the foot were palpable bilaterally, and his anterior lower extremity compartments were soft with the right more sensitive to palpation than the left but painless on passive flexion. The ankle-arm indexes were normal with 1.08 on the right and 1.11 on the left.

Spot x-rays from the ankle to the femur (image) revealed countless radiopaque pellets in his legs, with pellets embedded in the proximal left tibia and left knee joint space.

What additional imaging might be indicated for a patient with this type of injury?

Find the case discussion on page 26.

Diagnosis: shotgun pellet embolism

Gunshot wounds are relatively rare presentations of ballistic wounds, and they account for between two and nine percent of all firearm injuries. Little data has been published on injury patterns or injury types, and what data does exist is highly variable.

An epidemiological review reported that gunshot wounds in the United States represent a small percentage of ballistic injuries, but they cause significant morbidity and mortality and are associated with 14% in-hospital mortality and 7% emergency room mortality. (J Med Urgent. 2020;58[5]:720.)

Gunshot wounds to the head are, unsurprisingly, associated with the greatest injury severity, but injuries to the extremities are the most common. It is important to note that the majority of patients (79%) had injuries in more than one body region. Surgery is common in these patients, with approximately one-third of all patients undergoing surgery, most commonly receiving exploratory laparotomy, thoracotomy, and vascular procedures of the extremities. This high rate of surgical management is in part due to challenges associated with imaging and the high projectile load.

The key to proper management of shotgun bullet wounds lies in understanding the potential primary and secondary risks and screening for them appropriately. Gunshot wounds are a very heterogeneous group of injuries. Variables such as distance from which the patient was shot, type of shotgun pellet (buckshot, shot, simple slug), and anatomical distribution all make consistent assessment guidelines difficult. Many of these details are also missing in the emergency department.

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The risks of penetrating wounds to the abdomen or thorax are well established, especially when the shots are fired from less than 12 meters. (Trauma. 2009;67[6]:e202.) The rate of vascular damage is particularly high in extremity wounds. All but one emergency department patient with gunshot wounds to the extremities in one study required vascular exploration. (Emergency Trauma Surgery Eur J. 2020;46[6]:1351.) The approach for extremity wounds in particular should involve evaluation of primary vascular lesions via detailed pulse examinations, verification of ankle-arm indexes, and angiography studies.

Clinical examination and reflective imaging remain important to provide an initial assessment. Metal artifact pellets can cause false positive and false negative CT results. (Emergency Trauma Surgery Eur J. 2020;46[6]:1351.) Patients at risk of vascular injury, like our patient, are at risk of pellet embolism. It is often warranted to take x-rays to identify any areas of the body distant from the primary injury site that may contain granule emboli. Positive screening radiographs can guide further cross-sectional imaging to identify anatomical location and potential threat of pellet embolism. The procedure can be planned in consultation with traumatology and vascular surgery depending on the location and symptoms.

A case report and literature review identified 45 cases of lead/bullet emboli between 1995 and 2006. Seventeen of these were associated with gunshot wounds. Embolic events can occur in the venous and arterial circulation and are almost always anterograde, moving with the direction of blood flow in the vascular territory penetrated. (Trauma. 2009;67[6]:e202.)

Arterial pellet emboli are more often symptomatic than venous pellet emboli (69% versus 25%, respectively), and complications depend on the destination of the pellet. Arterial system complications are also usually more severe and may include ischemic stroke, peripheral tissue ischemia, visceral ischemia, and endocarditis. Venous complications can involve ischemia, thrombosis and infection. (Trauma. 2009;67[6]:e202.) Obviously, these wounds should be approached with caution and curiosity because you never know where these pellets may travel.

Our patient underwent CT imaging with angiography of his legs, and he had chest and abdominal X-rays to screen for pellet emboli. The film shown identified a solitary pellet located in the chest. CT imaging of the thorax confirmed a pellet embolism that had traveled to the azygos vein, probably following a lesion of the femoral vein. He was admitted to general surgery, observed for two days and discharged without complications or major interventions. A CT follow-up one month later showed pellet migration to the right ventricle. Transthoracic echocardiography showed no patent foramen ovale and no intervention was planned.

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Dr. Abruzzois a second-year emergency medicine resident at the University of New Mexico whereDr. Barrettis an associate professor of emergency medicine.