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Kidney Week

Abstract: TH-PO131

Don't Judge a Book by Its Cover: The Challenges of Diagnosing Nondilated Obstructive Uropathy

Session Information

Category: Trainee Case Report

  • 102 AKI: Clinical, Outcomes, and Trials

Authors

  • Shahzad, Muhammad Asim, Louis Weiss Memorial Hospital, Chicago, Illinois, United States
  • Baxi, Pravir V., Rush University Medical Center, Chicago, Illinois, United States
  • Rodby, Roger A., Rush University Medical Center, Chicago, Illinois, United States
Introduction

Nondilated obstructive uropathy (NDOU) is a rare and elusive cause of AKI since the diagnosis of obstructive uropathy (OU) depends on the demonstration of a dilated collecting system while the lack of rules it out. Reported in <5% of OU, NDOU has been associated with retroperitoneal malignancy, lymphadenopathy and fibrosis. The diagnosis requires a high index of suspicion and intervention despite normal radiographic screening studies. We present a case of AKI thought to be ATN where recognition and treatment of NDOU prevented irreversible ESRD.

Case Description

A 60-y/o woman with breast cancer complicated by metastasis to the retroperitoneal lymph nodes with a baseline serum creatinine (sCr) of 0.6 mg/dl was given zoledronic acid and one month later had a sCr of 1.3. She had decreased urine output and abdominal pain. Ultrasound and CT imaging showed no evidence of hydronephrosis. Her UA was benign. She became anuric and HD was initiated. Her AKI was postulated to be ATN from bisphosphonate use. A renal biopsy could not be performed because of DVTs requiring anticoagulation. She was discharged on HD. Despite normal imaging and a potential explanation for her AKI, there remained a clinical concern for NDOU. Bilateral retrograde pyelogram performed two weeks post-discharge showed no hydronephrosis. There were questionable areas of mild ureteral segmental narrowing and because her clinical course suggested obstruction, bilateral stents were placed. There was an immediate diuresis with an average output of about 300 ml/hr. Her sCr improved from 8.6 mg/dL to 0.8 mg/dL over the next 24 hrs (Fig.1).

Discussion

NDOU is a rare diagnosis that requires a high level of clinical suspicion. The lack of dilatation in NDOU has many pathophysiologic explanations, but is felt mainly to be secondary to the encasement of the collecting system. Direct visualization via retrograde or antegrade pyelography with empiric stent or nephrostomy tubes placement may be necessary when the concern for NDOU is high despite imaging lacking evidence of hydronephrosis.

Fig. 1