Internal Iliac Artery Aneurysmo–Colonic Fistula after Endovascular Stent-Graft Repair: A Case Report

Abstract

We describe rare ilio-enteric fistula that developed after endovascular repair of a left internal iliac artery aneurysm (IIAA). An 83-year-old man with a history of previous surgeries via laparotomies suddenly developed a high fever 3 years after undergoing endovascular abdominal aortic repair (EVAR) with a stent-graft to treat a left isolated IIAA. Computed tomography imaging revealed a fistula between the IIAA and the sigmoid colon. A colostomy was created because severe intraperitoneal adhesions prevented resection of the IIAA. The postoperative course was uneventful and the patient remained free of infection without antibiotics. Residual aneurysms can cause complications after EVAR.

Introduction

Internal iliac artery aneurysms (IIAA) usually progress asymptomatically, but they are fatal if they rupture.¹⁾ Such aneurysms sometimes create fistulae near organs such as the bladder, ureter, vein and intestinal tract.^1–6) We describe the rare development of a fistula between the sigmoid colon and a residual IIAA that developed in a patient 3 years after undergoing endovascular abdominal aortic repair (EVAR).

Case Report

An 83-year-old man underwent EVAR using a Zenith AAA endovascular graft (Cook Medical Inc., Bloomington, Indiana, USA) with coil embolization to treat an isolated left IIAA (maximum diameter 50 mm) 3 years previously. The distal branches of the internal iliac artery were not occluded, but the distal main trunk of the IIAA was treated by coil embolization. Endovascular abdominal aortic repair was originally selected because he had a history of total gastrectomy for gastric cancer as well as unknown procedures to treat colon and rectal cancer via several laparotomies. Postoperative computed tomography (CT) after EVAR revealed the absence of endoleaks and an unchanged aneurysmal diameter (Fig. 1). A high fever suddenly developed 32 months later, and his general practitioner found the following: white blood cells 8,400/μL and C-reactive protein, 5.8 mg/dL, indicating inflammatory changes. All other findings were unremarkable. He was prescribed with oral antibiotics (Cefcapene pivoxil hydrochloride hydrate, 200 mg/day) and sent home. However, he was admitted to hospital one week later with persistent fever and black tarry stools. The physical findings upon admission were as follows: body temperature, 38°C; blood pressure, 158/70 mmHg; heart rate, 70 beats/min. Plain CT showed that although the diameter of the IIAA sac had remained at 50 mm, it contained air bubbles (Fig. 2a). Colon fiberscopy revealed an ulcer at the sigmoid colon. Retrograde colonography showed gastrografin running into the IIAA sac (Fig. 2b). These findings confirmed a left IIAA-sigmoid colonic fistula without active bleeding from the IIAA. Gastroenterological surgeons ruled out radical surgery for IIAA–colonic fistula for this compromised patient and palliative surgery (colostomy creation) proceeded via a median laparotomy. Intraperitoneal adhesions were so severe that they could not be divided, especially between the sigmoid colon and the IIAA, and thus the sigmoid colon was transected at the oral position of the fistula. A colostomy was created at the oral side of the stump, the anal side of which was closed. The IIAA and the stent-graft remained untouched. The patient was post-surgically administered with meropenem (1 g/day for two weeks) and sulfamethoxazole- trimethoprim (1,800 mg/day for 5 months). The patient has remained free of symptoms of infection and melena for 1 year (Fig. 3).

Fig. 1.

Computed tomography (CT) after EVAR. Enhanced CT images at one week after EVAR (a and b). White arrow, left internal iliac artery aneurysm. Endoleak is not evident. Plain CT image at 31 months after EVAR (c). The aneurysm sac diameter has essentially remained unchanged at 50 mm. EVAR: endovascular abdominal aortic repair.

Fig. 2.

Internal iliac artery aneurysmo-sigmoid colonic fistula. White arrow in enhanced CT image shows internal iliac artery aneurysm with air bubbles (a). Black arrow in image of retrograde colonography (b) shows gastrografin in aneurysm.

Fig. 3.

Summary of perioperative course. First attendance at hospital after high-grade fever (Day 1); surgical colostomy (Day 17). CRP: C-reactive protein; WBC: white blood cell.

Discussion

Since IIAA usually remain clinically asymptomatic, they sometimes become obvious only when they rupture,¹⁾ and this can occur in the retroperitoneal space, veins, ureter, bladder and intestinal tract.^1–6) Treatment for IIAA comprises open surgery (resection of aneurysm) or EVAR. Open surgery for IIAA was not an option for our patient because of a hostile abdomen, and thus less-invasive EVAR with coil embolization was selected. However, EVAR is not radical and it does not always shrink aneurysms. Cieli, et al. reported that 53% of abdominal aneurysms shrink after EVAR,⁷⁾ indicating that 47% do not. Residual aneurysms that do not rupture can cause future complications via pulsatile stimulation towards nearby organs. Complications that can arise after thoracic endovascular aortic repair for a descending aortic aneurysm include aorto- esophageal (1.9%),⁸⁾ and aorto-jejunal fistulae after EVAR for abdominal aortic aneurysms.⁹⁾ Endoleaks did not occur after EVAR in our patient, but the IIAA did not shrink due to reasons that remain obscure. Melena did not persist in our patient after the fistula developed, indicating the absence of endoleaks after EVAR and a technically successful procedure in terms of excluding blood flow. However, the residual aneurysm sac resulted in an aneurysmo-colonic fistula. The fistula might have occurred due to pulsatile stimulation and compression by the residual solid aneurysm with thrombus causing ischemic changes in the retroperitoneal tissue and colon wall. Such changes could have caused necrosis in the colon wall that resulted in local aneurysmal infection and subsequent perforation of the infected aneurysm wall.

Internal iliac artery aneurysm–colonic fistulae can be treated for example, by aneurysmorrhaphy of the IIAA, ligation of the communicating vessel, colostomy, the Hartmann procedure and revascularization (femoro- femoral bypass etc.).^5,6) However, radical surgery for the IIAA–colonic fistula in our patient was not an option, and thus he underwent palliative procedures with a colostomy and the IIAA remained intact. The patient remained free of melena and symptoms of infection for over 1 year without antibiotics. The extent of infection was uncertain (only aneurysm sac or stent-graft). The only thing we can say for a hypothesis is that even if the stent-graft was infected, it might be localized. And if infected tissues (aneurysm sac, stent-graft) develop pus, open drainage might function effectively via a pathway from the aneurysm sac fistula to the anus (the fistula- sigmoid colon-rectum-anus).

Conclusion

As far as we know, this is the first report of a residual aneurysm forming a fistula with the colon after EVAR. Our findings suggest that the increasing prevalence of endovascular repair might increase the rates of complications associated with residual aneurysms.

Disclosure Statement

None of the authors has any conflicts of interest to declare.