A Unique Case of Spontaneous Bilateral Renal Subcapsular Urinoma Secondary to High Pressure Chronic Retention of Urine.

Subcapsular urinomas have been reported in the past as a presenting feature of ureteric or bladder outlet obstruction, generally in children, and often associated with neurogenic bladders. We describe a case of spontaneous asymptomatic bilateral subcapsular urinomas in an adult male with high pressure retention of urine secondary to bladder outlet obstruction. An extensive literature review shows this to be a unique case.

Introduction

Subcapsular urinomas have been reported in the past as a presenting feature of ureteric or bladder outlet obstruction,1, 2 generally in children,3, 4 and often associated with neurogenic bladders. Other instances of unilateral perinephric (extra-capsular) collections secondary to high pressure urinary retention have been described following routine laparoscopic surgery for umbilical hernia, locally advanced cervical cancer causing unilateral distal ureteric obstruction, and during intravenous urography of an obstructed ureter.

We describe a case of spontaneous asymptomatic bilateral subcapsular urinomas in an adult male with high pressure retention of urine secondary to bladder outlet obstruction. An extensive literature review shows this to be a unique case.

Case presentation

A 69-year old man was referred by his GP in September 2016 with nocturia and urinary incontinence.

During review in clinic in October 2016 he was noted to be urinary retention.

He was admitted for catheterisation and his blood tests suggested an acute kidney injury (AKI) with serum Creatinine 131 μmol/L and estimated Glomerular Filtration Rate (eGFR) 47 mL/min.

Following catheterisation, his renal function normalised with Creatinine 66 and eGFR >60. His renal ultrasound scan (U/S) was normal (Fig. 1). Against medical advice, he had his catheter removed and was discharged 3 days later.

Figure 1

Initial renal U/S in October 2016. Right kidney (a), left kidney (b).

He was re-admitted in January 2017 with delirium and AKI (Creatinine 286, eGFR 19). He was otherwise asymptomatic. He was re-catheterised and his renal function normalised. Another renal U/S showed bilateral subcapsular collections (Fig. 2).

Figure 2

Renal U/S during acute admission in January 2017. Right kidney (a), left kidney (b).

A CT urogram for clarification demonstrated bilateral subcapsular urinomas with mild hydroureteronephrosis and ureteric tortuosity (Fig. 3).

Figure 3

CT urogram in January 2017. Coronal (a), and axial (b) reconstructions.

He is being managed with an indwelling catheter and is awaiting an elective TURP.

Discussion

High pressure chronic retention of urine is a commonly encountered Urological emergency. Generally imaging reveals bilateral hydronephrosis. Spontaneous rupture of the collecting system bilaterally resulting in subcapsular urinoma is very unusual. In this scenario the patient would be expected to present with significant bilateral loin pain which should not be relieved by analgesia, but in this case the patient was completely asymptomatic. The patient's renal function normalised following catheterisation and it was decided to manage the urinomas conservatively instead of considering Radiological drainage as the patient remained completely asymptomatic. Follow-up imaging was planned to ensure resolution of the urinomas after decompression so that this patient does not eventually develop a Page kidney and hypertension, but the patient failed to attend repeated appointments and could not be contacted.

Conclusion

A full literature review suggests this is a unique case. While previous case reports have demonstrated unilateral extracapsular perinephric urinomas following distal obstruction, bilateral subcapsular urinomas from bladder outlet obstruction does not seem to have been reported previously. Unfortunately the patient failed to attend for all follow-up imaging and clinic appointments, denying us the opportunity to assess resolution of this unusual condition by conservative management. This case demonstrates the need for adequate upper tract imaging in all patients presenting with high pressure chronic retention of urine.

Conflicts of Interest

None.