artery - ureteral fistula ( auf ) is a relatively rare but life - threatening condition because of the potential of massive hemorrhage and hematuria . risk factors for auf include previous abdominal vascular surgery , previous extensive and radical oncologic treatment in the pelvis and chronic ureteral stenting .
because of the increased prevalence of these risk factors , the chances of encountering auf are increasing .
various treatment options have been reported to manage an existing fistula . conventionally , auf is treated by open surgery to close the fistula ; however , this is associated with high mortality and morbidity rates because the surgical field often has adhesions from previous treatments such as surgery or radiotherapy . recently
, endovascular stent graft placement for auf has been employed as a less invasive and safer therapeutic option with satisfactory outcomes .
herein , we present a case of auf after surgery for an abdominal aortic aneurysm , which was successfully treated with an endovascular procedure using a covered stent .
he had undergone a y - graft surgery for an abdominal aortic aneurysm 3 years earlier . a computed tomography ( ct ) , 1 year after y - graft surgery revealed that the right ureter had crossed the distal anastomosis of the vascular graft .
two years after the surgery , the ureter was observed to be extrinsically compressed by fibrosis at the site of its crossing over the y - graft and a ureteral stent was placed at another hospital , 7 months before presentation to us .
the patient was transferred to our hospital after transfusion of four units of red cell concentrates .
laboratory data showed anemia with a hemoglobin concentration of 9.7 g / dl ( normal , 13.517.0 g / dl ) , a hematocrit level of 28.9% ( normal , 4050% ) , an elevated serum creatinine level of 1.41 mg / dl ( normal , 0.40.8 mg / dl ) and a slightly elevated c - reactive protein concentration of 0.40 mg / dl ( normal , 0.000.30 mg / dl ) .
he was hemodynamically stable and a urine bacterial culture was negative . at the time of consultation at our
hospital , contrast - enhanced ct of the abdomen revealed a possible fistula between the right common iliac artery and the ureter , although no flow of contrast medium to the ureter was detected [ figure 1a ] .
the ct showed that the process originated at the level of the distal anastomosis of a vascular y - graft [ figure 1b and c ] .
an elective endovascular surgery was performed by vascular surgeons following embolization of the right internal iliac artery to prevent endoleak caused by backflow from the right internal iliac artery .
arteriography at the operation detected no leak from the artery to the ureter [ figure 2 ] .
covington , ga , usa ; diameter 10 mm ; length , 80 mm ) was placed via the right femoral artery .
extrinsic obstruction caused by inflammatory fibrotic change was considered to be so dense that it was impossible to treat the ureteral stricture .
two weeks after treatment , contrast - enhanced ct showed disappearance of the fistula and improvement of right hydronephrosis .
six months after the endovascular surgery , severe right hydronephrosis was observed with an elevated serum creatinine level of 1.42 mg / dl .
( a ) contrast - enhanced computed tomography ( ct ) in arterial phase shows a minimal process ( arrow ) that was a possible fistula between the right common iliac artery and the right ureter .
( b and c ) ct and 3d - ct angiography show that the right ureter with a ureteral stent crosses the distal site of anastomosis of the vascular graft ( arrow ) arteriography shows no leak of contrast medium to the right ureter .
urological complications after vascular surgery were previously considered to be rare because a unilateral hydronephrosis may not produce symptoms , mild obstruction may not be identified and no systematic follow - up after vascular surgery was performed .
however , it is now known that ureteral obstruction occurs in 1020% of all bypass operations .
patients with ureteral obstruction are significantly more likely to have graft complications , including auf , compared with those without ureteral obstruction . in particular , delayed ureteral obstruction , as observed in the present case , appears to be a marker for current or impending graft complications .
it is important to recognize the predisposing risk factors for auf , and the urologist should suspect auf in any patient with hematuria and the predisposing risk factors .
the pathogenesis of auf is closely related to inflammatory or ischemic changes in the ureter , vessels or both .
the predisposing factors from the outside of the ureter that could cause the pathogenesis are previous genitourinary or pelvic oncologic surgery , previous vascular surgery , radiotherapy and an underlying vascular disease .
in addition , chronic ureteral stenting is a strong predisposing factor from the inside of the ureter .
chronic ureteral stenting acts as a counter - brace to facilitate the transmission of arterial pulsations to a fragile ureter , producing pressure necrosis and resulting in fistula formation . in a previous study assessing a large patient cohort ,
85 of 139 auf patients ( 61% ) had chronic ureteral catheterization prior to the fistula formation .
auf in a patient who underwent vascular graft surgery is often located at the level of the proximal or distal anastomosis of the vascular graft .
this is because anastomosis is most fragile in the artery . in the review of 139 auf cases , a significant portion of the fistulas originated at the level of the anastomosis of the vascular graft .
consistent with this , the fistula in the present case was located at the level of the distal anastomosis .
the treatment of auf in an arterial lesion is either via an open procedure or via an endovascular procedure .
endovascular treatments are less invasive and safer than open procedures because they avoid direct procedures on areas damaged during previous radiation or surgery .
fox et al . reported that the overall endovascular success rate of no recurrent hemorrhage was 85% ( 12 of 14 cases ) , including 11 patients with endovascular stents with fewer complications than with open procedures .
endovascular treatment is classified into two categories : the first using angiographic vascular occlusion and the other using a covered stent .
the former procedure requires extra - anatomical vascular repair to maintain antegrade blood flow to the lower extremity .
however , an endovascular procedure using a covered stent does not require revascularization ; therefore , this treatment option can be considered less invasive than open procedures or endovascular treatment using angiographic vascular occlusion .
although endovascular treatment using a covered stent has some disadvantages , such as not dealing with fistula formation , severe complications such as stent occlusion or stent graft infection are very rare . additional cases and longer follow - ups are likely to demonstrate the further utility of endovascular procedures with covered stents . in conclusion , in a patient with history of treatment of aortic aneurysm , a ureteral stent should not be placed for a long time , and endovascular treatment of auf using a covered stent could become the preferred treatment modality because of its less invasiveness and safety .
 artery  ureteral fistula ( auf ) is a rare condition but there is an increase in the number of reported cases . 
 it is frequently difficult to treat . 
 a 63-year - old male who had undergone a dacron y - graft placement for an infrarenal aortic aneurysm 3 years earlier , presented with hematuria . 
 contrast - enhanced computed tomography revealed a fistula located between the right common iliac artery and the right ureter at graft anastomosis . 
 endovascular treatment using a covered stent was performed successfully . 
INTRODUCTION
CASE REPORT
DISCUSSION