Incidental Finding of Traumatic Arteriovenous Fistula in the Tibial Peroneal Trunk during Venous Duplex Ultrasound to Rule Out Deep Vein Thrombosis

Abstract

Traumatic arteriovenous (AV) fistulas are caused by injury to an adjacent artery and vein and can be potentially limb threatening. AV fistulas occurring at the level of the popliteal artery result in a 10% greater rate of amputation than those at the level of the common femoral artery. Clinical findings of AV fistula in the lower extremity are similar to that of deep vein thrombosis and include pain, swelling, and redness of the extremity. This case study demonstrates how a routine lower-extremity venous Duplex ultrasound led to the diagnosis of a traumatic AV fistula that required surgical repair. The patient presented to the emergency department with a cold foot and was found to have a thrombosed left iliac artery and femoral artery system. A thrombectomy catheter was used to remove the clot from the superficial femoral, above knee popliteal, and posterior tibial arteries. One week postoperatively, the patient had continued left thigh and calf pain and swelling; a lower-extremity venous ultrasound was ordered to rule out deep-vein thrombosis. Findings of the Duplex ultrasound were negative for deep-vein thrombosis; however, Doppler imaging revealed abnormal flow in both the venous and arterial systems of the left femoral and popliteal vessels. Venous flow was found to be continuous and turbulent. The arterial system had low resistance, marked spectral broadening, and high velocity. Normal venous flow is spontaneous, phasic, and pulsatile with respiration. Normal arterial flow in the lower extremities is high resistance and triphasic. Traumatic AV fistula was suspected in the tibial peroneal region, and confirmed with computed tomography angiography. The patient underwent surgical repair of fistula with vein graft.