The size of the gestational sac depends on the gestational age

The gestational sac is a very critical component in early pregnancy. Generally speaking, the size of the gestational sac depends on the duration of the pregnancy. The early stages of pregnancy are very critical. If you cannot develop well, the fetus will not develop healthily. Therefore, pregnancy tests are required at certain times. Prenatal check-up is the most important part of the entire pregnancy process. It can check whether the fetus of a pregnant woman is healthy. How to tell the gestational age from the size of the gestational sac?

How to read the gestational sac

The gestational sac is only seen in early pregnancy. For women who have regular menstruation of 28 to 30 days, after 35 days of amenorrhea, the gestational sac can be seen in the uterine cavity by B-ultrasound. The diameter of the gestational sac is about 2 cm at 6 weeks of pregnancy and about 5 cm at 10 weeks of pregnancy. It is normal for the gestational sac to be located at the fundus, front wall, back wall, upper part, or middle part of the uterus; it is normal for it to be round, oval, and clear in shape; if the gestational sac is irregular in shape, blurred, and located in the lower part, and the pregnant woman also has abdominal pain or vaginal bleeding, she may have a miscarriage.

Gestational sac size comparison table

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.

5 weeks: The fetus grows to 0.4 cm and enters the embryonic period. The amniotic cavity expands and primitive cardiovascular system appears, which 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.

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.

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.

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.

9 weeks: The fetus grows to 2.15 cm, the head is larger than the body, the various parts are 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.

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.

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.

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.