Abstract: TH-PO0723
Persistent Pyelogram Revealing Nondilated Obstructive AKI
Session Information
- AKI: Prevention, Diagnostics, and Management
October 22, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 101 AKI: Epidemiology, Risk Factors, and Prevention
Authors
- Shimada, Go, St Marianna University, Kawasaki, Japan
- Ogata, Masatomo, St Marianna University, Kawasaki, Japan
- Shibagaki, Yugo, St Marianna University, Kawasaki, Japan
Introduction
Obstructive acute kidney injury (AKI) is diagnosed based on urinary tract dilation on imaging studies. However, significant obstruction may still occur despite minimal/mild hydronephrosis. We report a case of non-dilated obstructive AKI diagnosed by persistent pyelogram on delayed computed tomography (CT).
Case Description
An 81-year-old woman with metastatic cecal cancer developed oliguric AKI, with serum creatinine increasing from 0.89 to 8.62 mg/dL over two weeks. She had a functionally solitary right kidney because the left kidney was atrophic. Contrast-enhanced CT demonstrated only mild right hydronephrosis (Figure A). Although a conventional ureteral stent was placed, kidney function did not improve, and persistent obstruction was considered unlikely. However, non-contrast CT performed several days later demonstrated persistent retention of contrast material within the right renal pelvis (Figure B), consistent with delayed contrast excretion (“persistent pyelogram”). Persistent obstruction was suspected despite minimal collecting system dilation. The conventional ureteral stent was replaced with a metallic stent, resulting in immediate diuresis and recovery of kidney function.
Discussion
This case highlights that severe obstructive AKI may still occur despite only mild hydronephrosis and lack of improvement after conventional ureteral stenting, both of which may reduce suspicion for a postrenal cause of AKI. Persistent retention of contrast material within the renal pelvis on delayed CT reflected impaired urinary drainage and supported ongoing obstruction despite minimal hydronephrosis and failed initial stenting. Replacement of the conventional ureteral stent with a more rigid metallic stent resulted in immediate diuresis and recovery of kidney function, strongly supporting persistent obstruction as the cause of AKI. Obstructive AKI should not be excluded solely because hydronephrosis is mild or initial ureteral stenting is ineffective, and persistent pyelogram may serve as a diagnostic clue.
Acknowledgment
All authors contributed substantially to the conception, drafting, and revision of the manuscript and approved the final version for publication.