CASE 18190 Published on 13.06.2023

Limb vascular trauma : A post traumatic popliteal pseudoaneurysm concomitant with an arteriovenous fistula

Section

Cardiovascular

Case Type

Clinical Cases

Authors

Ayoub Chetoui, Zineb Moudafia, Lamya Yazghi Martahe, Sara Mrani, Siham Alaoui Rachidi

 Radiology Department, Faculty of Medicine and Pharmacy, Abdelmalek Saadi University, Tangier, Morocco

Patient

22 years, male

Categories
Area of Interest Arteries / Aorta, Emergency, Extremities ; Imaging Technique Emergency, Extremities
Clinical History

A 22 years old adult male with no medical history, was victim of a penetrating glass trauma at his right popliteal fossa.

48h after the trauma, the patient presents in the ER with pain in the popliteal fossa. Clinical examination finds a painful and pulsatile mass in his right popliteal fossa

Imaging Findings

A Doppler US was performed and has found well-circumscribed circulatory sacs near the right popliteal pedicle, with a communicating neck from the parent artery. These sacs were associated with an infiltration of the soft parts and they were presenting a turbulent flow with the characteristic “yin-yang” sign on colour Doppler and they had shown an arterial spectrum on pulsed Doppler. The investigation has also revealed a connection between the popliteal artery and vein with arterialization of the vein downstream in pulsed Doppler.

A CT angiography of the lower limbs was then performed and it has shown an extravasation of the contrast product producing well-circumscribed circulating pockets adjacent to the interarticular popliteal pedicle, these were associated with infiltration and emphysema of the adjacent soft tissues.
The CT has also shown an opacification of the popliteal vein and the superficial femoral vein at arterial phase.

Discussion

There are five recognized types of vascular injuries: 1) intimal injuries (flaps, disruptions, or subintimal/ intramural hematomas); 2) complete wall defects with pseudoaneurysms (PA) or haemorrhage; 3) complete transections with haemorrhage or occlusion; 4) arteriovenous fistulas (AVF); and 5) spasm.  Extremities are their most common location ( 50% to 60% in the femoral or popliteal arteries, 30% in the brachial artery). (1)
The true incidence of posttraumatic PA and AVF has not been definitively demonstrated, but numerous cases have been reported sporadically (2) (3). Rich reported the largest series of peripheral vascular injuries where the rates of PA and AVF were 3.5 % and 3.9 %, respectively. (4)

Acute clinical features of PAs are the following: pulsating and/or painful swelling; downstream ischemia, hemorrhagic shock, or can be asymptomatic. (5)

 

Duplex Ultrasound, when used in the assessment of peripheral vascular trauma, especially pseudoaneurysms, has an excellent sensitivity ( > 95%) and specificity ( 97%) (6) (5).
The presence of a  neck communicating with the pseudoaneurysm, the "yin-yang" sign caused by swirling motion of blood within the pseudoaneurysm cavity and the "to-and-fro" spectral waveform within the neck with pan diastolic reversal of flow are the classic findings of pseudoaneurysm on doppler ultrasound. (7)

Colour Doppler sonographic findings that may suspects a AVF are the visualization of the fistulous communication between the artery and the vein, associated with a dilatation in the draining vein when chronic, with a high-velocity arterialized waveform; and a low resistance pattern with higher diastolic flow in the feeding artery's Doppler waveform (7).

CT  angiography is the gold standard in the assessment of limb vascular injuries (1). A meta-analysis (8) found a sensitivity of 96% and a specificity of 99% for CTA in the diagnosis of this entity.

Unenhanced CT scans may show a low-attenuation rounded structure arising from the feeding artery. Pseudo-aneurysmal rupture is indicated by intermediate or high attenuation (haemorrhage) next to the pseudoaneurysm, which might vary in attenuation depending on the age of the rupture. A contrast material–filled sac can be seen on a contrast-enhanced CT scan. However, the pseudoaneurysm may not fill completely with contrast material, leaving a low-attenuation area within it, indicating incomplete thrombosis. The donor artery is generally visible connecting with the pseudoaneurysm. (9)

AVF are suspected on CT as an early enhancement of the vein in the arterial phase, but it is generally confirmed with Doppler ultrasound.

Surgical management of posttraumatic pseudoaneurysms associated with AVF is the most adopted option. However, these injuries can be managed with an endovascular approach by deploying a stent graft across the fistulous opening and excluding the pseudoaneurysm and AVF from the circulation. Endovascular approach is most indicated when diagnostic of AVF is made at a chronic stage and significant enlargement of the venous structures with the potential nerve damage can cause difficulties for surgical approach. (10)

Written informed patient consent for publication has been obtained.

Differential Diagnosis List
Posttraumatic PA of the popliteal artery associated with an AVF
Intimal injuries (flaps, disruptions, or subintimal/ intramural hematomas)
Complete wall defects with haemorrhage instead of pseudoaneurysms
Complete transections with haemorrhage or occlusion
Final Diagnosis
Posttraumatic PA of the popliteal artery associated with an AVF
Case information
URL: https://www.eurorad.org/case/18190
DOI: 10.35100/eurorad/case.18190
ISSN: 1563-4086
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