Abstract: FR-PO015

Pseudo-AKI Due to “Reverse Autodialysis”: A Case of Spontaneous Rupture of the Urinary Bladder

Session Information

Category: Nephrology Education

  • 1302 Fellows and Residents Case Reports

Authors

  • Deal, Connor, Rush University Medical Center, Chicago, Illinois, United States
  • Zhao, Xixi, Rush University Medical Center, Chicago, Illinois, United States
  • Gashti, Casey N., Rush University Medical Center, Chicago, Illinois, United States
  • Korbet, Stephen M., Rush University Medical Center, Chicago, Illinois, United States
Background

Spontaneous rupture of the urinary bladder (SRUB) is rare and can appear to present as AKI. This “Pseudo” AKI results from reabsorption of Cr and urea across the peritoneal membrane, referred to as “reverse autodialysis”. We describe a case of SRUB following an alcohol binge.

Methods

A 46 yo WM p/w abdominal distention, anuria and AKI following a 2-day alcohol binge. On exam his abdomen was distended with urgency upon suprapubic palpation. Labs: BUN- 63 mg/dl, SCr- 6.4 mg/dl and SAlb-4.4 g/dl, LFTs were nml. A non-con abd CT showed large “ascites” and no urinary obstruction. Paracentesis yielded 5L of clear fluid with a Cr level elevated at 27 mg/dl indicating the presence of urine in the peritoneal cavity. A Foley catheter was placed with 12L of UOP over 1-hour. CT cystography demonstrated extravasation of contrast into the peritoneal space(Fig 1). At laparoscopy a 1cm defect at the superior dome of the bladder was repaired. Renal function normalized within two days.

Conclusion

SRUB in the setting of alcohol intoxication is thought to be due to altered sensorium and decreased urge to urinate. The volume of ingested alcohol and its diuretic effect further increase bladder filling. The pt’s elevation in BUN and Cr are the result of reabsorption of urine across the peritoneal membrane (“reverse autodialysis”). This gives the appearance of AKI when in fact GFR is normal. The rarity of SRUB as well as the nonspecific presenting symptoms of abdominal distention with ascites and AKI presents a diagnostic challenge. Analysis of the ascitic fluid for Cr to establish a urine leak is a critical diagnostic step. Treatment is immediate surgical repair of the bladder with good prognosis.

Fig 1. Foley catheter (F) penetration through the bladder (B) wall with contrast extravasation in the peritoneal cavity (white arrows).