Traumatic Arteriovenous Fistula

Gunshot wound right groin 2 weeks ago. Pulsatile thrill • Xray of the Week

Figure 1. What is the important finding on this CT scan and Doppler.

Figure 2:

A: pseudoaneurysm (red arrow)

B: right external iliac artery (green arrow), right external iliac vein (yellow arrow) Note there is contrast in it which is abnormal, left external iliac artery (white arrow), left external iliac vein (blue arrow) Note there is no contrast in it which is normal.

C: pseudoaneurysm (red arrow)

D: long axis doppler US of right femoral artery (green arrow) and femoral vein (yellow arrow). Note there is abnormal arterial flow in the vein and the flow direction is reversed.

E: short axis doppler US of right femoral artery (green arrow) and femoral vein (yellow arrow). Note there is abnormal arterial flow in the vein and there is a fistula visualized between the artery and vein.

Introduction:

An arteriovenous fistula (AVF) is an abnormal connection between an artery and a vein, which ultimately bypasses the capillary bed allowing blood to go directly into the venous system. Traumatic AVFs can be easy to miss, and up to 70% of patients are given a delayed diagnosis (1). AVFs need to be treated due to potential late complications including pseudoaneurysm (Figs. 1,2), high output heart failure, or AVF rupture resulting in hemorrhage (1). Patients can present with a thrill, bruit, or pulsatile hematoma, but also can be completely asymptomatic (1).

Discussion:

AVFs can be from an iatrogenic or traumatic source and can also be congenital. In our case, the patient had a gunshot wound to the right groin and presented with a pulsatile thrill. Gold standard for diagnosing AVFs is a CT angiography (CTA), although digital subtraction angiography (DSA) can accurately diagnose them but are less common (1, 2). Duplex and color Doppler sonography are also very useful imaging modalities. In our case, CTA showed contrast in the right external iliac vein (Fig. 2B, yellow arrow) during the arterial phase compared to the normal left side which demonstrates no contrast (Fig. 2B, blue arrow). Further supporting the diagnosis of the AVF is abnormal doppler flow in the femoral artery and vein (Fig. 2D, E). Our case showed communication between the superficial femoral artery and superficial femoral vein at the level of a 1.2 cm pseudoaneurysm. This indicates that there is a post-traumatic AV fistula in the right superficial femoral artery and superficial femoral vein in the proximal to mid-thigh.

Treatment:

No gold standard for treatment exist regarding repair of traumatic AVFs. In stable patients, AVFs can be treated with endovascular procedures via embolization or stenting (3, 4) to prevent progression of or subsequent complications. Other methods include primary repair of venous and arterial injuries with ligation (1).

References:

1. Shaban Y, Elkbuli A, McKenney M, Boneva D. Traumatic femoral arteriovenous fistula following gunshot injury: Case report and review of literature. Ann Med Surg (Lond). 2020;55:223-226. Published 2020 May 30. doi:10.1016/j.amsu.2020.05.016

2. Chen JK, Johnson PT, Fishman EK. Diagnosis of clinically unsuspected posttraumatic arteriovenous fistulas of the pelvis using CT angiography. AJR Am J Roentgenol. 2007;188(3):W269-W273. doi:10.2214/AJR.05.1230

3. Rogel-Rodríguez JF, Zaragoza-Salas T, Díaz-Castillo L, Noriega-Salas L, Rogel-Rodríguez J, Rodríguez-Martínez JC. Fístula arteriovenosa femoral postraumática, tratamiento endovascular [Post-traumatic femoral arteriovenous fistula, endovascular treatment]. Cir Cir. 2017;85(2):158-163. doi:10.1016/j.circir.2015.10.010

4. Liao JL, Wang SK, Dalsing MC, Motaganahalli RL. Endovascular Treatment of a Persistent Traumatic Deep Femoral Arteriovenous Fistula After Gunshot Injury. Vasc Endovascular Surg. 2020;54(5):441-444. doi:10.1177/1538574420918970​

Neal Joshi is a medical student and aspiring diagnostic radiologist at Rowan University School of Osteopathic Medicine in New Jersey. Prior to medical school, he did research with mouse models for Parkinson’s disease and L-DOPA induced dyskinesias. He also did an internship at Kessler Institute for Rehabilitation in a stroke lab analyzing MR images in ischemic stroke patients with hemispatial neglect. During his time at Rowan, he did research with animal models for traumatic brain injury with an emphasis on electrophysiology of neurons. He graduated from William Paterson University where he completed his studies in biology and biopsychology. Apart from medical school, Neal loves to read, skateboard, go on hikes, and spend time with his friends.

Update July 2022: Dr. Joshi is a Radiology Resident at Thomas Jefferson University in Philadelphia.

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Kevin M. Rice, MD is the president of Global Radiology CME and is a radiologist with Cape Radiology Group. He has held several leadership positions including Board Member and Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator. He was once again a semifinalist for a "Minnie" for 2021's Most Effective Radiology Educator by AuntMinnie.com. He has continued to teach by mentoring medical students interested in radiology. Everyone who Dr. Rice has mentored has been accepted into top programs across the country including Harvard, UC San Diego, Northwestern, Vanderbilt, and Thomas Jefferson.

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