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A condition characterized by an excess of amniotic fluid in the amniotic sac


Polyhydramnios is a term used to refer to the condition wherein there is an excess of amniotic fluid in the amniotic sac. An amniotic fluid that is more than 2000 mL or an amniotic fluid index of greater than 24 cm is considered a polyhydramnios.1, 2 It occurs in about 1% of pregnancies.<sup2</sup>

There are two forms of polyhdramnios: (1) chronic polyhydramnios in which the excess amniotic fluid accumulates gradually and (2) acute polyhydramnios wherein the excess amniotic fluid accumulates rapidly.

Polyhydramnios is associated with various conditions such as intrauterine infection, chorioangioma of the placenta, and twin-to-twin transfusion syndrome. In twin-to-twin transfusion syndrome, the monochorionic twins have anastomosing blood vessels and their blood supply is connected as they share one placenta. One of the tendencies in this form of twinning is the subsequent oligohydramnios in one twin and polyhydramnios in the other.

Word origin: poly- (many)

Also called:

  • polyhydramnion
  • hydramnios


See also:

1 Barnhard, Y., Bar-Hava, I., $ Divon, M. Y. Is polyhydramnios in an ultrasonographically normal fetus an indication for genetic evaluation?, Obstet Gynecol. 1995 Nov;173(5):1523-7.
2 Polyhydramnios. (n.d.) Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. (2003). Retrieved from [[1]].
3 Alexander, E. S., Spitz, H. B., & Clark, R. A. Sonography of polyhydramnios. AJR Am J Roentgenol 1982; 138:343