CASE REPORT

Obstructive ARF Caused by an Inflammatory AbdominalAortic Aneurysm

Rosa Sanchez, MD, Agustın Arroyo, MD, Ricardo Gesto, MD, Marıa J. Fernandez-Reyes, MD,Carmen Mon, MD, and Fernando Alvarez-Ude, MD

● Inflammatory abdominal aortic aneurysms are rare entities characterized by dense fibrosis typically envelopingthe aortic wall and adjacent structures with distinctive clinical features that differentiate them from typicalatherosclerotic aneurysms. The inflammatory process can involve the renal excretory pathways, causing ureteralobstruction in 20% of cases. The authors report 2 cases of complete obstructive anuria secondary to inflammatoryaneurysms and discuss the most appropriate management for these situations of hydronephrosis. Surgical repairof the aneurysm usually leads to regression of the inflammatory reaction. Am J Kidney Dis 41:E9.© 2003 by the National Kidney Foundation, Inc.

INDEX WORDS: Anuria; aortic aneurysm; inflammatory aneurysm; obstructive uropathy; retroperitoneal fibrosis.

THE OVERALL incidence of acute obstruc-tive renal failure is difficult to estimate,

because a wide and varied range of causes exists,depending on patient age, sex, and associatedconditions. In the prospective and multicenterstudy conducted by Liano et al,1 10% of 748cases of acute renal failure were found to besecondary to obstructive disease. Obstructiveuropathy usually has a bimodal distribution, witha first peak in children, in whom congenitalabnormalities play a significant role. The inci-dence subsequently decreases in adulthood andagain increases after the age of 60 to 65 years,mainly in men as a result of prostatic disease.Other possible causes to be considered in middle-aged individuals are stones, pelvic neoplasms,and pregnancy in women.

Abdominal aortic aneurysms (AAA) shouldbe considered among the causes of obstructiveuropathy caused by extrinsic compression of theupper urinary tract above the ureterovesical junc-tion.2 A variant of AAA, called inflammatoryabdominal aortic aneurysm (IAAA), is character-ized by the presence of an adventitial layer offibrosis, preferentially located in its anterior andlateral side.3 This fibrotic reaction confers theaneurysm clinical, diagnostic, and prognosticcharacteristics different from those seen in themore common degenerative or atheroscleroticaneurysm. The clinical differences are attribut-able to the adherence or entrapment of adjacentstructures in the fibrotic component. One of thestructures that can become enveloped by thethick fibrotic adventitial layer of the aorta is theureter. In fact, the first description of such an

aneurysm was made by James in 19354 in apatient with uremia caused by bilateral hydrone-phrosis. Ureteral involvement is seen in about20% of cases according to the classical series.5

Bilateral involvement is less common,6 and casesinitially manifesting as anuria are exceptional.7-9

We report 2 cases of acute renal failure withanuria caused by bilateral ureteral obstructioncaused by IAAAs. The cases were separated intime by several years, and different approacheswere used to manage hydronephrosis in eachpatient, a fact that gives us the opportunity todiscuss the different management options.

CASE REPORTS

Case 1A 62-year-old man presented with lower back pain for the

previous month, mainly on the left side and irradiating alongthe ureteral trajectory, associated with asthenia, anorexia,and weight loss (8 kg). The pain had been attributed to renalcolic on several occasions. The clinical history found asmoking habit and myocardial infarction 4 years before. Thephysical examination found a pulsatile periumbilical mass.The laboratory tests showed creatinine levels of 3.8 mg/dL

From the Department of Nephrology, Segovia GeneralHospital and the Department of Angiology and VascularSurgery, 12 de Octubre, University Hospital, Madrid, Spain.

Received July 9, 2002; accepted in revised form Novem-ber 6, 2002.

Address reprint requests to Rosa Sanchez Hernandez,MD, Servicio de Nefrologıa, Hospital General de Segovia,Carretera de Avila s/n, 40002-Segovia, Spain. E-mail:agarbi@mixmail.com; arroyobi@yahoo.es

© 2003 by the National Kidney Foundation, Inc.1523-6838/03/4103-0023$30.00/0doi:10.1053/ajkd.2003.50136

American Journal of Kidney Diseases, Vol 41, No 3 (March), 2003: E9 1

(336 �mol/L) and a sedimentation rate of 60 mm in the firsthour, with the rest of the parameters being normal. Anabdominal ultrasound scan showed bilateral pyelocalicealdilation (discrete on the left side and moderate on the right)that was confirmed in an intravenous urography, which alsoshowed medial deviation of the right ureter (Fig 1). Acomputed tomography (CT) showed an infrarenal abdomi-nal aortic aneurysm 4.5 cm in diameter with the presence ofa fibrous band surrounding the aneurysm on its anterior andlateral aspects. With the diagnosis of IAAA, an arteriogra-phy was performed to better plan surgical treatment of theaneurysm. During the study phase, renal function worsenedprogressively to anuria, requiring bilateral ureteral catheter-ization with a double J catheter. After recovery of renalfunction, the patient was subjected to endoaneurismorraphywith interposition of an aortobifemoral Dacron graft, to-gether with the release of both ureters (ureterolysis). Thepostoperative course was uneventful, and the ureteral cath-eters were removed after 6 days. The patient was dischargedafter one week with creatinine levels of 1.2 mg/dL (106�mol/L) and died after 12 months of coronary disease. Thehydronephrosis and periaortic fibrosis had disappeared pre-viously as evidenced by a CT follow-up study.

Case 2A 63-year-old man came to the emergency service with

anuria for the previous 24 hours, drowsiness, and a poorgeneral condition. His medical history included smoking,

moderate alcohol consumption, mild prostatic syndrome,and colonic diverticulosis. The physical examination showeda pulsatile periumbilical mass and blood pressure values of170/100 mm Hg. The laboratory findings upon admissionincluded creatinine levels of 10.2 mg/dL (902 �mol/L),potassium levels of 6.4 mEq/L (6.4 mmol/L) and a sedimen-tation rate of 50 mm in the first hour. An ultrasound scanshowed grade II/IV bilateral hydronephrosis with an emptybladder and an abdominal aortic aneurysm. The conditionwas defined as obstructive acute renal failure, and emer-gency cystoscopy was used to place bilateral double Jureteral catheters. Ascending pyelography confirmed theexistence of bilateral proximal ureterohydronephrosis withmedial deviation of the ureters. A computed tomography(CT) scan showed an aneurysm involving the infrarenalabdominal aorta and both iliac arteries, with a maximumdiameter of 8 cm and abnormal thickening of the aortic wall,characteristic of inflammatory aneurysms (Fig 2). After therecovery of diuresis (after a polyuric phase) and renalfunction (creatinine, 1.4 mg/dL [124 �mol/L]), arteriogra-phy was performed, and the patient was subjected to endo-aneurismorraphy with interposition of an aortobifemoralDacron graft. The catheters were removed 30 days later.After a 24-month follow-up, the patient is asymptomatic,with a normal renal function, and no periaortic fibrosis isseen in the control CT, although minimal renal ectasiapersists.

DISCUSSION

The etiology of obstructive acute renal failureincludes conditions that may require surgery foreffective management. IAAA is a rare variantaccounting for 4.5% to 15% of all AAAs.5,10 Thisform of aneurysm, of unknown etiology, is mac-roscopically characterized by an increased wallthickness as a consequence of firm and scleroticfibrosis, with a suggestive histopathologic pic-ture in which 3 observations stand out: thicken-ing of the media and, mainly, adventitial layers,with a lymphoplasmocytic infiltrate; obliteratingendarteritis of the vasa vasorum; and fibrosisaround the lymphatic and nervous structures.11

This fibrotic reaction confers the aneurysm clini-cal characteristics different from those of themore common degenerative aneurysm, as a re-sult of the entrapment or adhesion within thefibrotic component of adjacent structures such asduodenum, inferior vena cava, left renal vein,and sigmoid. However, ureteral involvement hasthe greatest clinical implications, leading to sec-ondary hydronephrosis and a potential impair-ment of renal function that can evolve towardatrophy if allowed to become chronic. Thesetypes of aneurysms may have clinical similaritieswith retroperitoneal fibrosis. Only 4% of patients

Fig 1. Intravenous urography showing medial devia-tion of the right ureter and hydronephrosis.

SANCHEZ ET AL2

with retroperitoneal fibrosis go on to have aorticaneurysms.

Atherosclerotic or degenerative aortoiliac an-eurysms rarely cause hydronephrosis, and com-plete ureteral obstruction is even less common.Moreover, if hydronephrosis occurs, it is usuallycaused by lateral displacement of the distal ure-ter at its crossing with the aneurysm of thecommon iliac or hypogastric arteries. In the caseof inflammatory aneurysms, the obstruction lieshigher up. Instead of ureteral displacement, thelatter becomes entrapped within the aortic wall.For this reason, medial deviation of the ureter inthe urographic study is a characteristic finding.5

Other clinical features that differentiate inflam-matory from atherosclerotic aneurysms includethe greater incidence of pain (lumbar or abdomi-nal) and an increased erythrocyte sedimentationrate.

In cases of impaired renal function secondaryto obstructive uropathy, initial managementshould mainly include preferential drainage ofkidneys using a rapid decompression techniquebefore the aneurysm is repaired, with the dualobjective of not prolonging renal damage12 andimproving the general condition of a patientbefore surgery when aortic clamping is per-formed.

Some controversy has traditionally existed asto the ideal management approach for hydrone-

phrosis in these patients. Some investigators ad-vocate preoperative corticoid therapy to reducethe inflammation and thus improve the hydrone-phrosis.13 However, this approach may theoreti-cally increase the probability of rupture of theaneurysm caused by thinning of the wall, with agreater risk of infection of vascular prosthesisand the possibility of ureteral rupture. We are ofthe opinion that in patients with inflammatoryaneurysms, steroid therapy should be reservedfor cases of hydronephrosis and impaired renalfunction where the aneurysm cannot be operatedon based on anesthetic criteria. Other investiga-tors propose systematic intraoperative ureteroly-sis, as in our first case.14 However, this is a riskyprocedure that may increase the intra- and post-operative urologic complications.15 Perhaps themost widely accepted and applied practice cur-rently is conservative management, because manyinvestigators have reported regression of the peri-aortic fibrosis after surgery of the aneurysm.5,16

The main objective of this report is to pointout the existence of an unusual and rarely consid-ered cause of obstructive uropathy. In manycases, simple abdominal palpation can guide theetiologic diagnosis of obstructive acute renalfailure. The triad of abdominal pulsatile mass,pain, and hydronephrosis is highly suggestive ofan inflammatory aneurysm, with CT being theimaging technique of choice.

Fig 2. CT scan of an in-flammatory abdominal aor-tic aneurysm with the charac-teristic adventitial fibrosis.

ANURIA AND INFLAMMATORY ANEURYSM 3

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