P10.02: Idiopathic polyhydramnios and antenatal Bartter syndrome: diagnostic criteria?

Audit idiopathic polyhydramnios for the last 5 years in a tertiary fetal medicine unit. Correlate the current biochemical criteria in the diagnosis of antenatal Bartter syndrome (ABS) with neonatal outcome. A retrospective audit of amniodrainages for polyhydramnios from the database of all procedures for the last 5 years was performed. Antenatal diagnosis of Bartter syndrome was followed up with neonatal outcomes. A total of 109 amniotic fluid drainages was performed during the time period. The diagnosis was based on an AFI of > 25 cms or DVP > 9 cms. Of those with apparent ‘idiopathic polyhydramnios’ (no ultrasound detectable cause), four pregnancies, demonstrated recurrent polyhydramnios needing repeated amniodrainages. Antenatal Bartter syndrome was suspected in each of these four cases based on their clinical presentations and biochemical criteria in table 1 (Garnier et al. total protein levels mean value of 1.6g/L or Chloride > 111 mmol/L). However, each of the cases had an uncomplicated neonatal course and were found not to have neonatal Bartter syndrome. Management of recurrent idiopathic polyhydramnios is challenging and often requires repeated therapeutic amniodrainage procedures or medication to decrease fetal urinary output. Serious adverse outcomes in both the neonate and mother related to polyhydramnios and its management has been reported. Biochemical criteria for diagnosis of ABS is unreliable. Genetic testing for using fetal DNA from amniotic fluid can be performed and may be preferable than using biochemical parameters to establish a diagnosis of ABS.