Acute ureteral obstruction secondary to bullous cystitis of the trigone: report of 2 cases.

Two boys presented with acute bullous cystitis limited to the trigone and periureteral zone and producing marked but transient acute ureteral obstruction. One patient was anuric and likely would have died without intervention. Cystoscopy in both cases showed localized bullous edema of the bladder mucosa; biopsy showed acute inflammation, mucosal edema, and lymphangiectasis. Radiological findings included distal ureteral obstruction and numerous nodular filling defects in the bladder, caused by the edema. The etiology of the cystitis could not be determined in either case.