SMFM Consult Series #46: Evaluation and management of polyhydramnios

Polyhydramnios, or hydramnios, is an abnormal increase in the volume of amniotic fluid. Identification of polyhydramnios should prompt a search for an underlying etiology. Although most cases of mild polyhydramnios are idiopathic, the 2 most common pathologic causes are maternal diabetes mellitus and fetal anomalies, some of which are associated with genetic syndromes. Other causes of polyhydramnios include congenital infection and alloimmunization. The purpose of this document is to provide guidance on the evaluation and management of polyhydramnios. The following are Society for Maternal-Fetal Medicine recommendations: (1) we suggest that polyhydramnios in singleton pregnancies be defined as either a deepest vertical pocket of ≥8 cm or an amniotic fluid index of ≥24 cm (GRADE 2C); (2) we recommend that amnioreduction be considered only for the indication of severe maternal discomfort, dyspnea, or both in the setting of severe polyhydramnios (GRADE 1C); (3) we recommend that indomethacin should not be used for the sole purpose of decreasing amniotic fluid in the setting of polyhydramnios (GRADE 1B); (4) we suggest that antenatal fetal surveillance is not required for the sole indication of mild idiopathic polyhydramnios (GRADE 2C); (5) we recommend that labor should be allowed to occur spontaneously at term for women with mild idiopathic polyhydramnios; that induction, if planned, should not occur at <39 weeks of gestation in the absence of other indications; and that mode of delivery should be determined based on usual obstetric indications (GRADE 1C); and (6) we recommend that women with severe polyhydramnios deliver at a tertiary center due to the significant possibility that fetal anomalies may be present (GRADE 1C).