What fluid-filled structure is associated with early pregnancy and may be located inside the uterus or outside it in ectopic pregnancy?

What fluid-filled structure is associated with early pregnancy and may be located inside the uterus or outside it in ectopic pregnancy?

• A. Gestational sac
• B. Amniotic sac
• C. Chorion
• D. Placenta

Answer: (A)

The main idea is the gestational sac—the fluid-filled cavity that forms around the developing embryo in early pregnancy. It’s the first pregnancy-related structure you look for on ultrasound and normally sits inside the uterus. But in ectopic pregnancy, this sac can be located outside the uterine cavity, such as in the fallopian tube, which is a crucial clue for diagnosis. The other structures aren’t the initial fluid-filled cavity of early pregnancy: the amniotic sac forms later around the fetus inside the gestational sac, while the chorion and placenta are parts of the fetal membranes and the placenta, not the early universal fluid-filled cavity itself.

The main idea is the gestational sac—the fluid-filled cavity that forms around the developing embryo in early pregnancy. It’s the first pregnancy-related structure you look for on ultrasound and normally sits inside the uterus. But in ectopic pregnancy, this sac can be located outside the uterine cavity, such as in the fallopian tube, which is a crucial clue for diagnosis. The other structures aren’t the initial fluid-filled cavity of early pregnancy: the amniotic sac forms later around the fetus inside the gestational sac, while the chorion and placenta are parts of the fetal membranes and the placenta, not the early universal fluid-filled cavity itself.