Amniotic fluid biochemistry in isolated polyhydramnios: a series of 464 cases.

OBJECTIVE: To report amniotic fluid biochemistry in a large series of 464 cases of isolated polyhydramnios in order to analyze both the outcome and the benefit of amniotic fluid biochemistry. METHODS: This retrospective cohort (2008-2012) included polyhydramnios cases for which amniotic fluid samples were sent to our laboratory for biochemical analysis (total protein, alpha-fetoprotein and gamma-glutamyl transpeptidase) so as to investigate the etiology. A Bartter index and an esophageal atresia index were defined. Final diagnoses were compared between groups to determine the association between these indices and the frequency and type of adverse outcomes. RESULTS: Among 464 cases of polyhydramnios considered isolated at ultrasound examination, severe fetal diseases were diagnosed in 136 (29.3%): 46 (9.9%) chromosomal anomalies, 28 (6%) Bartter syndrome, 23 (4.95%) other genetic syndromes, 22 (4.75%) swallowing disorders and 17 (3.7%) uro-nephrological disorders. Amniotic fluid biochemistry identified esophageal atresia with 66.6% (10/15) sensitivity and 100% specificity and Bartter syndrome with 85.7% (24/28) sensitivity and 84.2% specificity. CONCLUSION: Isolated polyhydramnios is associated with a high risk of severe fetal diseases. Molecular cytogenetics and amniotic fluid biochemistry are helpful tools.