Child Kidney Dis.  2021 Dec;25(2):133-139. 10.3339/jkspn.2021.25.2.133.

Primary Subcapsular Reflux as an Etiology of Subcapsular Renal Abscess

• Yoo EJ
• Oh JH
• Jung HJ
• Lee SJ
• Park JE
• Pai KS

• KMID: 2524516
• DOI: http://doi.org/10.3339/jkspn.2021.25.2.133

Abstract

Herein, we report two rare cases of renal infection. The first case was renal subcapsular urine reflux in a 8-month-old girl with recurrent urinary tract infection and the second was subcapsular abscess in a 14-year-old girl with diabetes, who was successfully treated with percutaneous drainage. It has been suggested that renal subcapsular abscesses could be caused by the direct reflux of urine into the subcapsular space, rather than spread of infection from an existing parenchymal lesion, and that complete recovery can be achieved if percutaneous drainage is performed in a timely manner. We propose primary subcapsular reflux, in which urine directly refluxes upwards into the subcapsular space of the kidney, as one of the mechanisms for development of renal subcapsular abscesses.

Keyword

Abcess; Drainage; Urinary tract infections; Vesico-ureteral reflux

Figure

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  Fig. 1. Serial ultrasound examinations of the right kidney on May 7, 2018 (A), 6 weeks later on June 15 due to recurrent infection (B), and 3 years later on May 24, 2021 (C).

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  Fig. 2. Voiding cystourethrogram taken on October 5, 2018 showed grade II reflux, with leak of contrast medium to the entire subscapsular space of right kidney (A), and this was proved as subcapsular collection on the lateral view (B). There was no evidence of extrarenal leakage until urination was completed during examination (C).

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  Fig. 3. Renal computed tomography on January 25, 2021 showed abscess formation in the upper and lower portion of right kidney (A) and the follow-up exam on February 1, 2021 revealed that the size of abscesses had expanded (B).

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  Fig. 4. A percutaneous drainage catheter was inserted into the subcapsular pocket to drain pus on February 2, 2021 (A) and VCUG was performed on 3 days after admission with no evidence of reflux stream (B). Renal ultrasonography on January 25, 2021 showed an abscess at the lower pole of the right kidney (C-1). This lesion disappeared 4 days after PCD, and the PCD catheter tip was noted (arrow) (C-2). Follow-up examination on February 24, 2021 showed complete recovery of the right kidney (C-3).

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  Fig. 5. Tc-99m DMSA renal scan on February 3, 2021 showed large photon defect in lower portion of right kidney (A), and the lesion completely disappeared on the follow-up exam after 6 months (B).

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  Fig. 6. Classification of renal abscesses: picture produced by the authors to facilitate understanding of the differential diagnosis of renal abscesses based on their locations.

Reference

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