Gestational Sac

**Definition:** Round-shaped structure usually located in the upper fundus of the UTERUS in early pregnancy. It comprises EMBRYO; AMNIOTIC FLUID; and YOLK SAC. It is visible in PRENATAL ULTRASONOGRAPHY by the fifth week of pregnancy. Its size is often used to determine and monitor GESTATIONAL AGE; FETAL GROWTH; and PREGNANCY COMPLICATIONS.

**Tree numbers:** - A16.535

**Synonyms:** - Gestation Sac