Prenatal diagnosis of bilateral isolated fetal hyperechogenic kidneys. Is it possible to predict long term outcome?

OBJECTIVE: To study perinatal and long term outcome following prenatal diagnosis of hyperechogenic kidneys.

DESIGN: Prospective observational cohort study.

SETTING: The Maternité Port-Royal Hôpital Cochin and at the Departments of Obstetrics and Paediatric Nephrology, Necker Enfants Malades in Paris, France.

POPULATION: Forty-three fetuses with isolated bilateral hyperechogenic kidneys.

METHODS: All patients referred with isolated bilateral hyperechogenic fetal kidneys were followed up prospectively up to 34-132 months. The following prenatal items were analysed: fetal kidney size, amniotic fluid volume, gestational age at diagnosis, family history and renal ultrasound in parents. Postmortem examination was carried out in cases with perinatal death. Postnatal follow up of survivors included postnatal ultrasound, blood pressure, serum creatinine, proteinuria, need for restricted diet, weight and height and renal biopsy when available.

MAIN OUTCOME MEASURES: Aetiology of hyperechogenicity, perinatal mortality and renal function in survivors.

RESULTS: The aetiology could be established by family history, postmortem or postnatal data, but not by prenatal ultrasound. There were 20 autosomal recessive, 8 autosomal dominant polycystic kidney diseases, 9 other renal disorders and 6 symptom-free survivors without aetiological diagnosis. There were 19 terminations of pregnancy, 5 neonatal deaths and 19 survivors, of whom 14 had normal renal function three had mild and two had end stage renal failure. None of those with severe oligohydramnios and fetal kidneys > 4 SD survived (n = 14, 10 terminations and 4 neonatal deaths), whereas of the 17 with normal amniotic fluid volume and kidneys < 4 SD, 14 survived, of whom 9 were symptom-free.

CONCLUSION: Aetiology could not be established prenatally in the absence of familial data. Kidney size and amniotic fluid volume were the best prenatal predictors of outcome.