Under normal circumstances, if you have a regular menstrual cycle and have a normal intrauterine pregnancy, a small gestational sac will be visible on B-ultrasound 37 days after menopause. This is also the earliest known time of pregnancy so far. . However, the time of conception depends on individual differences. Generally speaking, when you are just pregnant, the gestational sac is very small. As the gestational age increases, the gestational sac will continue to grow. Usually in the 5th week of pregnancy, the small gestational sac can be seen through B-ultrasound. By the 6th week, it can be seen more clearly, and the embryo can also be seen.

For women with normal and regular menstruation (28-30 days), the gestational sac can usually be seen in the uterine cavity around the 5th week of pregnancy (35 days). However, due to the problem of early and late implantation, some pregnant mothers can Early or late, five weeks: the fetal sac grows to 0.4 cm. The B-ultrasound can already see the small fetal sac, primitive cardiovascular and pulsating phenomena. The total volume accounts for less than 25% of the uterine cavity. In addition, when the diameter of the gestational sac reaches about 2 cm, the fetal bud and fetal heartbeat can be seen. If the fetal heartbeat is not seen by about 7 weeks of pregnancy, you need to be alert to whether the embryo has stopped developing and the sac is empty.

It is said that the size of the gestational sac is about 16--19mm at 5 weeks of pregnancy, about 25mm at 6 weeks of pregnancy and growing at a rate of about 1mm every day. There are individual differences in gestational sac size, so don't worry if it's too big or too small. Therefore, general hospitals will recommend that pregnant women come to the hospital for B-ultrasound examination after 60 days of pregnancy. At this time, the doctor can clearly see the development of the gestational sac, fetal bud and fetal heart.

The gestational sac is also the fetal sac or gestational sac. In the early stages of pregnancy, the embryo exists in this form. The normal fetal sac is located on the posterior wall, front wall, side wall, upper arm and middle part of the uterus. It is oval or round in shape and is relatively regular. It is 2mm at 4 weeks of gestation, 4mm at 5 weeks of gestation, 8.5mm with fetal bud appearing at 6 weeks gestation, 13.3mm with fetal heart rate appearing at 7 weeks gestation, 16.6mm at 8 weeks gestation and the yolk sac can be seen.