A gestational sac is a sign of twins

The gestational sac is a type of tissue that forms at the beginning of a woman's pregnancy. Pregnant women can go to the hospital for a check-up and let the doctor look at the shape and size of the gestational sac to infer whether the baby in her belly is healthy. Moreover, the gestational sac will gradually grow larger as the number of days of pregnancy increases, but it will disappear after a certain period of time. Twins are a type of pregnancy that many people want, so if there is only one gestational sac, can it be a sign of twins?

How long does it take for ultrasound to show the gestational sac?

1. The gestational sac is the initial form of pregnancy. It is a small embryo wrapped in the original placental tissue by the amniotic membrane and vascular network. The fetus had not yet formed at that time, but the fetal heartbeat was already there when the embryo bud appeared.

2. The gestational sac is very small at the beginning and then grows slowly. Generally speaking, after 5 weeks of pregnancy, a small gestational sac can be seen on B-ultrasound, which occupies less than 1/4 of the uterine cavity, or a fetal bud can be seen. If it is a normal intrauterine pregnancy, the gestational sac can be seen in the uterus through B-ultrasound around 40 days of pregnancy. However, due to individual differences in the time of conception, some pregnant women may not be able to see it until around 45 days.

3. Usually, when hCG reaches 1000U/L, vaginal ultrasound should be able to identify the intrauterine gestational sac. This is around the 4th or 5th day of the 5th week of pregnancy. When hCG reaches 6500U/L, abdominal ultrasound can identify the intrauterine gestational sac. Therefore, vaginal ultrasound will be more accurate. If the intrauterine gestational sac is not seen on the 49th day of pregnancy during a normal menstrual cycle, ectopic pregnancy should be suspected.

Is it possible to have twins with one gestational sac?

A gestational sac may be that of identical twins, but if there is only one fetal heartbeat, it can be confirmed that you are having a single baby.

How many gestational sacs there are for twins depends on the situation. In general, there are two placentas in dizygotic twins. Monozygotic twins depend on the time of differentiation, and there are four or five types. I can’t remember exactly. In short, two babies who look the same may have the same placenta.

If the twins are of different sexes, they are definitely fraternal twins. If the genders are the same, further differentiation is required. At birth, your doctor may tell you that the two babies came from one placenta or two placentas. How many gestational sacs a twin has depends on the sex of the fetus.

One placenta indicates identical twins, and two placentas indicate fraternal twins. But this notion is wrong. Although the condition of the placenta and fetal membranes has a certain relationship with the ovulation of twins, it is not absolute, so it cannot be judged based solely on this.