Polyhydramnios

Pathological excess of amniotic fluid in the amniotic cavity during pregnancy, typically diagnosed sonographically by elevated amniotic fluid index or deepest vertical pocket measurements. Possible causes are increased fluid production (polyuria due to maternal diabetes), impaired fluid removal (esophageal/duodenal atresia, CNS disorders with failure to swallow), genetic conditions (trisomy 21/18/13), twin-to-twin transfusion syndrome, fetal anemia (Rh blood type incompatibility), and congenital infections (CMV, toxoplasmosis, parvovirus).