Ureteral xanthine calculus and aberrant umbilical artery causing ureteral obstruction.

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A 30 -month -old girl presented with gastrointestinal symptoms and a febrile urinary tract infection . Sonographic and radiographic imaging demonstrated left hydronephrosis due to a radiolucent ureteral stone . Surgical exploration identified an aberrant , patent left umbilical artery causing ureteral obstruction . Stone and urine analyses revealed hereditary xanthinuria that had not previously been recognized in this child and her family .