The Prognostic Value of Normal Amniotic Fluid Volume in Severe Fetal Renal Anomalies

Introduction:

Amniotic fluid (AF) is an important indicator for fetal renal function. While oligohydramnios may indicate impaired fetal renal function, the prognostic value of normal AF volume in severe fetal renal anomalies (RA) is uncertain. Our aim was to determine the association between normal AF volume and postnatal renal outcome in fetuses with severe RA identified during pregnancy.

Material and Methods:

A single center retrospective observational study based on medical records of women referred for prenatal nephro-genetic consultation due to sonographic finding of severe RA, between 1997– 2018. Severe RA included bilateral findings of: echogenic/cystic/hypoplastic kidneys and severe hydronephrosis. A severe renal outcome was defined by: renal autopsy findings or post-natal sonographic or biochemistry results, which indicated a high probability for renal failure in the first decade of life. Postnatal renal outcome was analyzed in relation to AF volume status.

Results:

Twenty five fetuses were included in this study, of them 20 fetuses had normal AF volume and 5 fetuses had abnormal AF volume. All 5 fetuses with abnormal AF volume had severe postnatal renal outcome. Of the 20 fetuses with normal AF volume, 7 (35%) had severe postnatal renal outcome. Subgroup analysis of fetuses with echogenic kidneys (n=10) composed of 4 fetuses with abnormal AF volume and 6 with normal AF volume, displayed that 50% of the fetuses with normal AF volume had severe renal outcome.

Conclusions:

Normal AF volume is not a protective prognostic factor in cases of sonographic findings of severe renal anomalies in fetuses.

Abbreviations: AF- amniotic fluid, RA- renal anomalies