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Gestational Sac


Updated June 26, 2014

Gestational Sac

Image of a Gestational Sac in Early Pregnancy

Photo © A.D.A.M.

A structure that develops in the uterus early in pregnancy, enclosing the developing baby and amniotic fluid.

In an ultrasound, the gestational sac should be visible by five weeks of pregnancy. Measurement of the gestational sac diameter (GS) should increase by about 1 mm per day in early pregnancy.

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