Fetal renal biopsies in obstructive uropathy: feasibility and clinical correlations--preliminary results.

Final assessment on the outcome of fetal obstructive uropathy is a challenging matter. Ultrasonography, fetal urine electrolytes, and beta 2 microglobulin are postulated as being useful in many cases. For cases in which renal function remains unclear, ultrasound-guided fetal kidney biopsy may be used in order to detect histologic features distinctive of renal dysplasia. We present preliminary results aimed at studying the feasibility and possible risks. Biopsies were initially performed in 11 severely malformed fetuses, three of them with associated renal abnormalities. The success rate in obtaining renal material was 63.6 per cent with no maternal complications. In the next phase of this study, ten biopsies and urine collections were performed in fetuses with bilateral obstructive uropathy. The success rate was 50 per cent with no complications. Normal fetal renal histology was seen in 80 per cent of cases. In one case, although electrolytes were normal, a histologic diagnosis of renal dysplasia was made, showing a good correlation with outcome. In conclusion, fetal kidney biopsies for obstructive uropathy are feasible and further studies are needed to show their clinical relevance and risks.