Is the yolk sac a gestational sac?

Many female friends think that the yolk sac is the gestational sac. In fact, this idea is wrong, because the yolk sac and the gestational sac are two different symptoms. The yolk sac is a sac-like substance of ordinary tissue and is a disease wrapped in the gestational sac. However, when the gestational sac appears, the yolk sac does not necessarily appear. So female friends should not misunderstand them. Regarding the difference between yolk sac and gestational sac, female friends can learn about the content introduced in the following article.

1 Is the yolk sac the gestational sac?

The yolk sac is not the gestational sac, the two are different. The yolk sac is the first extraembryonic structure within the gestational sac that can be seen by ultrasound.

The scientific name of the gestational sac is gestational sac, which is formed by the growth of the fertilized egg. The size of the gestational sac is generally used to calculate the number of weeks of pregnancy. The yolk sac is located in the gestational sac, usually close to the fetal bud. It will disappear when it grows to a certain size. It mainly provides nutrition, immunity, metabolism, endocrine and hematopoiesis for the embryo.

2 Is the yolk sac the gestational sac? - The difference between the yolk sac and the gestational sac

1. Contained in the contained The gestational sac is a sac-like substance that wraps all normal tissues. The yolk sac is inside the gestational sac and later develops into embryonic tissue.

2. The formation time is different. The gestational sac is the initial form of pregnancy. At that time, the fetus has not yet formed. The gestational sac comes first and then the yolk sac. When the gestational sac can be seen on B-ultrasound, it is almost the same time when the yolk sac appears. First the yolk sac appears, followed by the embryonic bud and the fetal heart.

3. Different sizes: The gestational sac and the yolk sac are different in size. Because the yolk sac is wrapped by the gestational sac, the yolk sac must be smaller than the gestational sac.

4 Is the yolk sac the gestational sac? Gestational sac size and gestational age comparison table

1. 4 weeks: The fetus is only 0.2 cm. The amniotic cavity is formed just after the fertilized egg has implanted and its volume is very small. Ultrasound cannot show clear signs of pregnancy.

2.5 weeks: The fetus grows to 0.4 cm and enters the embryonic period. The amniotic cavity expands, primitive cardiovascular system appears, and may beat. B-ultrasound can show a small gestational sac, which occupies less than 1/4 of the uterine cavity, or a fetal bud can be seen.

3.6 weeks: The fetus grows to 0.85 cm, and the head, brain alveoli, facial organs, respiratory, digestive, and nervous organs are differentiated. The fetal sac is clearly visible on B-ultrasound, and the fetal bud and fetal heartbeat are seen.

4.7 weeks: The fetus grows to 1.33 cm. The embryo has the rudiments of a human being. The body segments are fully differentiated, the limbs are separated, and various systems are further developed. B-ultrasound clearly shows the embryo and fetal heartbeat, and the gestational sac occupies about 1/3 of the uterine cavity.

5.8 weeks: The fetus grows to 1.66 cm. The fetal shape is determined, and the head, body and limbs can be distinguished. The head is larger than the trunk. B-ultrasound shows that the gestational sac occupies about 1/2 of the uterine cavity, the fetal shape and fetal movement are clearly visible, and the yolk sac can be seen.

6.9 weeks: The fetus grows to 2.15 cm, the head is larger than the body, the various parts appear clearer, the skull begins to calcify, and the placenta begins to develop. B-ultrasound shows that the gestational sac almost fills the uterine cavity, the fetal outline is clearer, and the placenta begins to appear.

7. 10 weeks: The fetus grows to 2.83 cm, all fetal organs have been formed, and the rudiments of the placenta are formed. B-ultrasound shows that the gestational sac begins to disappear, a crescent-shaped placenta is visible, and the fetus is active in the amniotic fluid.

8. 11 weeks: The fetus grows to 3.62 cm, the fetal organs develop further, and the placenta develops. B-ultrasound showed that the gestational sac had completely disappeared and the placenta was clearly visible.

9.12 weeks: The fetus grows to 4.58 cm, the external genitalia begin to develop, any deformities will be revealed, and the calcification of the skull becomes more complete. The skull halo is clear, the biparietal diameter can be measured, obvious deformities can be diagnosed, and the internal organs tend to become more complete afterwards.