Deep Thigh Abscess after Coil Embolization of a Pseudoaneurysm of the Profunda Femoris Artery

Abstract

A 50-year-old male with peripheral arterial disease, end-stage renal disease, diabetes mellitus, and atherosclerotic cardiovascular disease, who had been treated with multiple percutaneous peripheral and coronary artery stents, presented with a 3-d history of fever and an enlarging, painful mass in his left groin. A computed tomographic (CT) scan with intravenous contrast revealed an 11.4x9.2-cm pseudoaneurysm of the left profunda femoris artery (Fig. 1), presumed to be from an attempted femoral venous catheterization during a prior hospitalization. The patient also had Escherichia coli bacteremia, a urinary tract infection with the same strain of E. coli responsible for his bacteremia, and a paraspinal abscess, which were treated with vancomycin and ceftriaxone. After 4 wks of a planned 6-wk course of antibiotic treatment for his paraspinal abscess, blood and urine cultures were negative, and the patient underwent successful endovascular coil embolization (ECE) of the pseudoaneurysm with multiple Nester^® platinum embolization coils (Cook, Bloomington, IN). For periprocedural prophylaxis he was given cefazolin (1 g q 8h) for 24 h.

FIG. 1.

Axial contrast-enhanced computed tomography scan of the lower extremities demonstrating a pseudoaneurysm of the left femoral artery prior to coil embolization.

At 3 months after embolization, and having been well during this interval, the patient developed pain and an enlarging, tender mass in his left thigh. His vital signs were normal and his white blood cell count was 15,200 cells/mm³. A CT scan was notable for a 12.8x13.7-cm cavitary mass of the left groin that contained gas, fluid, and a foreign body consistent with a vascular coil (Fig. 2). Piperacillin–tazobactam was administered before surgical drainage and debridement of an infected clot and multiple vascular coils. Culture of the clot and hardware demonstrated E. coli with antibiotic susceptibilities identical to those of the prior isolates. Postoperatively the patient was treated with local wound care and piperacillin–tazobactam.

FIG. 2.

Axial contrast-enhanced computed tomography scan of the lower extremities demonstrating an abscess containing an air-fluid level and a foreign body. The abscess measured 13.7 cm by 12.9 cm.

Pseudoaneurysms occur after 0.1%–0.2% of diagnostic angiograms and 3.5%–5.5% of interventional procedures [1]. Pseudoaneurysms <2 cm usually resolve without intervention; larger or symptomatic pseudoaneurysms may require treatment, such as compression, ultrasound-guided thrombin injection, or ECE (especially for larger lesions), which is being used increasingly.

No prospective randomized trial has examined the role of antibiotic prophylaxis for ECE, but reports of infected coils are few [2]. Falagas et al. reviewed seven cases of ECE that were complicated by infection, with intervals between the procedure and infection ranging from 10 days to 3.5 years [2]. The most common presentation was abscess (85.7% of cases). Of the seven cases reviewed, three had infections caused by Staphylococcus aureus; other pathogens included Salmonella spp., Staphylococcus epidermidis, E. coli, and Bacteroides fragilis. Owing to the paucity of reports, conclusive association of risk factors with infection of endovascular coils is impossible. Two putative mechanisms of coil infection are probable: Introduction of an infecting organism during coil placement or hematogenous seeding of an endogenous pathogen.

Historically, a higher incidence of transient bacteremia is recognized after embolization of endovascular coils than with diagnostic angiography, although the relevance is unknown [3]. Routine prophylaxis for ECE is controversial; when used, prophylaxis is targeted against skin pathogens. We suspect that our patient developed infection of an ECE and his pseudoaneurysm sac as the result of transient bacteremia from a colonized urinary tract or as a residuum of his paraspinal abscess. In theory, coil-related pseudoaneurysms become isolated from the circulation and should create a low risk for hematogenous seeding [4]; however, loose packing of the aneurysm may lead to failure of the formation of fibrinous neoendothelium [5] and allow colonization or infection by hematogenous seeding.

Treatment of infected coils must be individualized. If the abscess can be drained and the coil can be removed, this is the preferred option for controlling the source of the infection. However, case reports have described intracranial coil-related abscesses that have been treated successfully with antibiotics [2]. If explantation is impossible because of the location or position of coils, prolonged administration of high-dose antimicrobial agents may be necessary.

References

Kronzon

. Diagnosis and treatment of iatrogenic femoral artery pseudoaneurysm: A review. J Am Soc Echocardiogr, 1997; 10:236–245.

Falagas

, Nikou

, Siempos

. Infections related to coils used for embolization of arteries: Review of the published evidence. J Vasc Interv Radiol, 2007; 18:697–701.

Venkatesan

, Kundu

, Sacks

et al.

Practice guidelines for adult antibiotic prophylaxis during vascular and interventional radiology procedures. Written by the Standards of Practice Committee for the Society of Interventional Radiology and Endorsed by the Cardiovascular Interventional Radiological Society of Europe and Canadian Interventional Radiology Association [corrected]

J Vasc Interv Radiol, 2010; 21:1611–1630.

Stiver

, Porter

, Willinsky

et al. Acute human histopathology of an intracranial aneurysm treated using Guglielmi detachable coils: Case report and review of the literature. Neurosurgery, 1998; 43:1203–1208.

Shimizu

, Kurata

, Takano

et al. Tissue response of a small saccular aneurysm after incomplete occlusion with a Guglielmi detachable coil. AJNR Am J Neuroradiol, 1999; 20:546–548.