The impact of perinatal urinoma formation on renal function: our experience and review of the literature

Abstract

A urinoma is a fluid mass consisting of extravasated urine in the perirenal space. Its impact on renal function was analysed. All cases of prenatal and neonatal urinoma reported in the literature were analysed as well as two cases recently observed in our department. A review of all prenatally diagnosed urinomas revealed 25 cases, for a total of 30 renal units. The cause of obstruction was: lower urinary tract (LUT) obstruction in 16 cases (62.5%), upper urinary tract (UUT) obstruction in seven cases (29.5%) and unknown in two cases (8%). A preserved renal function was found in only 30% of all cases. Furthermore, prognosis for renal function was better in posterior urethral valve (PUV) patients than in uretero-pelvic junction obstruction (UPJO) patients. In addition, we analysed 35 published cases of urinoma with a neonatal onset, without prenatal diagnosis, and secondary to LUT obstruction in 27 cases (77%), UUT obstruction in seven cases (20%), while the underlying cause was unknown in one cases (3%). A preserved renal function was observed in 84% of cases with UUT obstruction and in 80% of cases presenting a LUT obstruction. Prognosis concerning renal function seems to be mainly related to two factors: age at presentation and underlying diagnosis. Decompression of the urinary tract by urine extravasation produces the best results in terms of preservation of the renal function in LUT obstruction (75% in prenatal and 84% in postnatal cases); UUT obstruction however is associated with a good prognosis in the neonatal period (80% of preserved renal function) but with a severe impairment (only 20% of preserved renal function) in prenatally detected cases.