Report on The Society for Fetal Urology panel discussion on the selection criteria and intervention for fetal bladder outlet obstruction.

INTRODUCTION

The Society for Fetal Urology panel section at the 2016 Fall Congress featured a multidisciplinary discussion on appropriate patient selection, the conservative versus surgical management, and postnatal renal outcome of fetuses with lower urinary tract obstruction (LUTO).

SELECTION CRITERIA FOR INTERVENTION

Rodrigo Ruano shared his experience of prenatal intervention, presenting the outcome of 111 fetuses with severe LUTO treated with vesicoamniotic shunting (VAS) (n = 16), cystoscopy (n = 34) or no intervention (n = 61) in a non-randomized series. Multivariate analysis at the 6-month follow-up suggested a significantly higher probability of survival with fetal intervention versus no intervention. A clear trend for normal renal function was present in the fetal cystoscopy group, but not in the VAS group. In cases in which there was a postnatal diagnosis of posterior urethral valves (n = 57), fetal cystoscopy was effective in improving both the 6-month survival rate and renal function, while VAS was associated with an improvement in the 6-month survival rate. In an attempt to better define which fetuses would benefit from intervention, Michael Braun explained the proposed LUTO classification system that incorporates: (1) fetal urinary biomarkers of renal injury; (2) amniotic fluid levels as a surrogate for the severity of obstruction; and (3) imaging studies to identify signs of renal dysplastic or cystic changes. Intervention was not recommended in patients at low risk of either renal disease or pulmonary hypoplasia (Stage 1). Vesicoamniotic shunting was performed in patients at high risk of either progressive renal injury or pulmonary hypoplasia without evidence of severe pre-existing renal damage (Stage 2). For those patients, who at the time of evaluation had evidence of severe renal disease (Stage 3), fetal intervention was individualized and often based on bladder capacity and bladder refilling after vesicocentesis. He went on to present the nephrologic outcome of fetuses managed over the last 3 years utilizing the selection criteria. Craig Peters supported the concept of selective criteria and discussed the cautious viewpoint, namely: (1) the procedure may be unnecessary, as it is possible for patients to do well, in spite of severe prenatal obstruction; and (2) the risk of giving partial treatment by allowing the baby to survive to delivery with the daunting postnatal journey of renal and pulmonary insufficiency.

CONCLUSION

Standardized patient selection utilizing a staging system is undoubtedly the way forward and will enable comparable long-term renal and bladder functional outcome studies.