Perinephric Urinoma as a Complication of an Ureteropelvic Junction Obstruction- A Case Report

Background: Urinomas are very rare and result from urine extravasation from the urinary tract. They can have an obstructive or a non-obstructive cause. We report a case of a 13-year-old boy with spontaneous perinephric urinoma secondary to a previously unknown right ureteropelvic junction obstruction (UPJO).

Case Presentation Summary: A 13-year-old boy, with an earlier 6 years` loss of pediatric follow up due to right pielocalicial dilatation, presented with a 1-day history of right flank pain and vomiting. He had no fever, any change in bowel habits, urinary symptoms or change in macroscopic urine characteristics. Previous trauma or surgery were denied. He was hypertensive, prostrated, had sunken eyes and abdominal guarding and pain on abdominal palpation of the right flank. Laboratory evaluation: hemoglobin 15,10g/dL, WBC count 15900cells/uL (88,0% neutrophils), platelets 281000/uL, creatinine 1,01mg/dL, BUN 23mg/dL, normal electrolyte panel, CRP <0,1mg/dL. He started intravenous fluid therapy and was medicated with ondansetron. Afterwards, he started to complain of lumbar pain and presented a first episode of macroscopic hematuria, maintaining right flank abdominal pain and hypertension. Laboratory revaluation made 6 hours later showed persistance of leukocytosis and neutrophilia and a rise in creatinine’s value (1,23 mg/dL). Urinalyses confirmed the presence of hematuria. Enhanced abdominal CT showed right hydronephrosis with dilatation of the renal pelvis (5,5cm of transverse diameter), which had saccular aspect and presented an abrupt transition to a normal ureter, and significant densification of the perirenal fat attributable to urinary extravasation. Cystoureterography showed contrast extravasation by the right renal lower pole. He was submitted to a bilateral double J stenting and medicated with ceftriaxone, with clinical improvement.

Discussion: Urinomas occur most commonly following renal trauma or surgery. This case has particular interest since it reports perinephric urine extravasation as a complication from UPJO.