In utero fetal urine analysis and renal histology correlate with the outcome in fetal obstructive uropathies.

We evaluated 8 second-trimester fetuses who had undergone termination because of obstructive uropathies and correlated the renal histopathology with fetal urine biochemical prognostic parameters. Prenatal evaluation included serial vesicocentesis, karyotyping, and sonography. According to the urinary biochemical parameters, 3 fetuses were classified to be in the good prognostic category, 2 in the borderline prognostic category, and 3 in the poor prognostic category. The kidneys were evaluated both grossly and microscopically for hydronephrosis, pelvicaliceal dilatation, cystic changes and fibrosis. Fetuses in the poor prognostic category had severely damaged renal architecture, microcysts, macrocysts, and extensive fibrosis. Fetuses in the good prognostic category had minimal histopathologic changes with preservation of the architecture. Fetuses in the borderline category showed a moderate degree of renal damage but with focally preserved architecture. We conclude (1) that there is a direct correlation between elevation in urinary electrolytes and proteins and extent of underlying renal histopathological damage and (2) that appropriate detailed prenatal evaluation of the renal function can identify fetuses who could potentially benefit from in utero therapy.