Antenatal Bartter Syndrome as a Rare Cause of Severe Polyhydramnios: A Case Report and Review of the Literature

ABSTRACT Severe polyhydramnios occurs in 1%–2% of pregnancies and may be associated with maternal diabetes, fetal structural anomalies, genetic disorders, or remain idiopathic. Among the rare etiologies is Bartter syndrome, a renal tubular defect causing impaired salt reabsorption. We report a rare case of severe polyhydramnios secondary to antenatal Bartter syndrome to emphasize clinical and biochemical features that aid in early diagnosis. A 36‐year‐old primigravid woman developed severe polyhydramnios at 26 weeks (AFI 30 cm, moderate polyhydramnios), which progressed to 44 cm (severe polyhydramnios) despite two therapeutic amnioreductions. Amniotic fluid analysis showed markedly elevated chloride (104 mmol/L). A male neonate was delivered at 36 weeks with normal birth weight and Apgar scores. At 3 months, he presented with polyuria, dehydration, hypokalemic hypochloremic metabolic alkalosis, confirming Bartter syndrome. The presence of severe polyhydramnios, together with elevated chloride levels, may be supportive in the diagnostic evaluation. Incorporating biochemical analysis and targeted genetic testing in the prenatal assessment may facilitate earlier recognition and improve neonatal outcomes. Prompt diagnosis can prevent morbidity, guide management, and reduce delay in the treatment of affected infants.