Extensive Retroperitoneal Fibrosis with Duodenal and Ureteral Obstruction Associated with Giant Inflammatory Aneurysm of the Abdominal Aorta

Abstract

We report a case of abdominal aortic aneurysm complicated by retroperitoneal fibrosis with both duodenal and bilateral ureteral obstruction. The patient underwent successful bilateral transurethral ureteral stenting, and then he was referred for surgical treatment of the aneurysm. Massive retroperitoneal fibrosis was found at surgery, and the mass was removed along with the diseased aorta, which was replaced by a bifurcated Dacron prosthesis; duodenolysis and ureterolysis were concomitantly performed. Ureteral stents were removed on the 8th postoperative day. Follow-up assessment at 1 year showed normalization of the urinary tract structure at echography and good hemodynamic performance of the vascular prosthesis at Doppler examination. To our knowledge, no other case of duodenal and bilateral ureteral stenosis secondary to massive retroperitoneal reactive fibrosis in association with abdominal aortic aneurysm has been reported. (Tex Heart Inst J 2003;30:311–3)

Evidence of ureteral involvement is reported in up to 71% of patients with abdominal aortic aneurysms, ¹ but involvement of the duodenum is rare. ² To our knowledge, no other reports have been issued to date of both duodenal and bilateral ureteral obstruction secondary to extensive perianeurysmal fibrosis.

We report a case of surgical cure in a patient who had an abdominal aortic aneurysm complicated by both duodenal and bilateral ureteral obstruction.

Case Report

In September 2000, a 69-year-old man was referred to an outlying hospital for a pulsatile abdominal mass and oliguria with strangury. The patient had recently complained of sickness and emesis after eating.

The patient's history was positive for diabetes, hypertension, and coronary artery disease, for all of which he was receiving medical treatment. The left ventricular ejection fraction at echocardiography was nearly normal, even though inferior wall akinesia was present. Serum screening upon admission showed a serum creatinine level of 6.5 mg/dL, BUN of 140 mg/dL, and serum potassium level of 5.6 mEq/L; all the other routinely measured values fell within normal ranges. His physical examination was negative except for a pulsatile mass in the mesogastric region upon abdominal palpation. Distal lower-limb pulses were all present and normal.

The abdominal echocardiographic study showed bilateral dilatation of the renal calyces with proximal ureteral involvement. Moreover, it revealed an abdominal aortic aneurysm, with a maximal diameter of 7.0 cm, largely encircled by a hypo-echogenic, fibrotic, retroperitoneal mass. Excretory urography demonstrated poor left kidney opacification and severe ureteral stenosis. On the right side, it revealed hydronephrosis and severe distal ureteral stenosis.

The abdominal computed tomographic (CT) scan (Fig. 1) revealed an abdominal aortic aneurysm (6 cm in diameter) that began 5 cm distal to the origin of the renal arteries and was encircled by a large amount of fibrotic tissue. This tissue extended into the retroperitoneal space, involving the duodenum, ureters, and iliac vessels.

Fig. 1 Abdominal computed tomographic scans show the aortic aneurysm and perianeurysmal mass. Proximal ureteral and cal yceal dilatation, as well as duodenal involvement, are evident.

The patient underwent successful transurethral bilateral ureteral stenting and was then transferred to our institution for surgery. Upon admission, he was asymptomatic. Preoperative laboratory tests demonstrated mild chronic renal failure: a serum creatinine level of 3.2 mg/dL, BUN of 122 mg/dL, and serum potassium level of 5.2 mEq/L. An abdominal radiograph showed correct positioning of the ureteral stents (Fig. 2). Abdominal ultrasonography showed moderate bilateral ectasia of the calyces, with mild proximal ureteral dilatation.

Fig. 2 Abdominal radiograph shows correct positioning of the ureteral stents.

A surgical procedure was performed through a xipho-pubic median laparotomy. At intraoperative examination, we found massive retroperitoneal fibrosis, extending from the left renal vein to the iliac vessels. It was whitish in aspect and 4 cm thick. The fibrotic tissue involved mainly the distal portion of the aneurysmal abdominal aorta, including the bifurcation, which rendered infeasible the exposure of the com mon iliac arteries. The external iliac arteries were clamped. The fibrous mass was almost completely excised. Proximally, the left renal vein was heavily involved, while the inferior vena cava was comparatively unaffected. However, it was possible to isolate the left renal vein, thereby creating infrarenal access to the aorta to enable aortic clamping. Detachment of the fibrous mass from the duodenum was performed by means of electrocautery; in order to avoid visceral lesions, we left a layer of fibrous tissue of a few millimeters in thickness. Complete cleavage of both ureters down to the vesicular junction was performed quite easily, since they were included in the lateral margin of the retroperitoneal mass. The aneurysm was not entirely excised, and a bifurcated prosthesis was anastomosed proximally to the aorta with the endoluminal technique, and distally end to end with the common iliac arteries. Finally, we included the vascular graft prosthesis within the aneurysmal native aortic wall.

The postoperative course was uneventful. The patient was discharged in good physical condition on the 6th postoperative day, with partially recovered renal function (serum creatinine level, 2.0 mg/dL; BUN, 100 mg/dL).

At histologic examination, the mass was characterized by a diffuse fibroblastic proliferation with high cellular density, a great number of collagen fibers, and a chronic inflammatory infiltrate (lymphocytes, plasma cells, neutrophilic granulocytes, and histiocytes). This tissue entrapped vessels and nerves. The arteries showed intimal fibromuscular hyperplasia. Fibrosis and inflammatory processes infiltrated the aortic adventitia and, marginally, the aortic media. Moreover, aortic atheroma, with cholesterol crystals and intimal hyperplasia, was observed.

On the 8th postoperative day, the patient underwent successful transurethral bilateral ureteral stent removal.

The 1-year follow-up visit showed improved kidney function (serum creatinine, 1.3 mg/dL; BUN, 79 mg/dL), normalization of urinary tract structure, and good hemodynamic performance of the vascular prosthesis at echo-Doppler evaluation.

Discussion

Although extrinsic ureteral stenosis is reported in up to 71% of patients referred for abdominal aneurysms, ¹ ureteral obstruction secondary to perianeurysmal fibrosis is uncommon. ³ Reported cases of duodenal obstruction in association with abdominal aortic aneurysm are even fewer. ^1,2 To the best of our knowledge, only 1 other case of associated duodenal and ureteral obstruction has been described in the world literature; ¹ in that report, the duodenal obstruction was a consequence not of extensive fibrosis but of compression of the duodenum in its retroperitoneal course between the aneurysmal aorta and the superior mesenteric artery.

The cause of such fibrosis is still unknown. ⁴ Periureteral extension of the inflammatory disease that has affected the aorta and mere coincidence (the coexistence of idiopathic retroperitoneal fibrosis and an abdominal aneurysm) are the 2 main pathophysiologic mechanisms that have been proposed. ^4,5 Diagnosis and treatment are controversial as well. ⁶

Urinary tract symptoms in the presence of aortic aneurysms are usually nonspecific and tend to be overlooked. Abdominal ultrasonography proved a reliable screening test, since it can detect perianeurysmal fibrosis. ³ Subsequent urography and an abdominal CT scan can enable more accurate anatomic definition of the disease. ^2,6

Relief of ureteral obstruction can be accomplished by aneurysm replacement alone, ⁷ by aneurysm replacement in association with ureterolysis, or by ureteral stenting, previous or subsequent to one of the above procedures. ^1,6 In our experience, preoperative ureteral stenting resulted in significant improvement of renal function as shown by both serum analysis and abdominal ultrasonography. Stable excretory function enhanced perioperative safety for the patient and substantially simplified surgical management and out come. Combined prosthetic graft placement and ureterolysis are, in our opinion, the best operative strategy. One-stage surgery does not carry much additional risk and helps to assure stable results. In cases in which ureterolysis has not been performed intra-operatively, the need for it following prosthetic implantation has been reported, so consistent radiologic monitoring at short intervals has been advocated for these patients. ^1,5

In regard to the duodenal obstruction, relief of the compression should be achieved thorough aortic graft placement and duodenolysis, rather than through gastrointestinal bypass.

In conclusion, abdominal aortic aneurysm should be considered as a possible cause of duodenal or ureteral stenosis, particularly in the elderly. Preoperative ureteral stenting and subsequent combined prosthetic graft placement and ureterolysis may be proposed as a 2-stage approach aimed at improving perioperative management and at achieving long-lasting results without the need of close radiologic monitoring.