Differential Diagnosis and Prognosis of Fetuses with Bilateral Enlarged, Hyperechogenic Kidneys: Renal Volume and Amniotic Fluid Volume with Advancing Gestation

Introduction This study's objective was to identify prenatal criteria helping differential diagnosis of bilateral enlarged, hyperechogenic kidneys, especially looking at development of renal volume and amniotic fluid volume with increasing gestational age. Method Retrospective analysis (single-center database) of all bilateral enlarged, hyperechogenic kidneys between 2000-2018. Renal enlargement was defined as renal volume>90 (th) percentile. Evaluation included development of renal and amniotic fluid volume during pregnancy and fetal outcome. Results 23 cases fulfilled the inclusion criteria. 12 pregnancies were terminated. For 11 continued pregnancies, longitudinal information on amniotic fluid volume and renal volume were available. 4 cases with oligohydramnios showed a progressive reduction; 6 cases with normal/increased amniotic fluid volume remained stable; in 1 case amniotic fluid volume normalized from initially being oligohydramnios. Regarding renal volume, 4 cases showed exponential enlargement, 3 cases linear progression; in 2 cases renal volume stabilized after initial progression; 2 cases showed initial progression and secondary regression. 4 fetuses survived: 3 autosomal dominant polycystic kidney diseases, 1 Bardet-Biedl syndrome. Conclusion Progressive reduction of amniotic fluid volume with exponential increase of renal volume is highly suggestive for autosomal recessive polycystic kidney disease. Cases of autosomal dominant polycystic kidney disease show a linear progression of renal volume>90 (th) percentile and mostly normal amniotic fluid volume.