The yolk sac is a manifestation of the normal development of fetal tissues after pregnancy. The yolk sac is a manifestation of the differentiation of embryonic tissues that occurs around the 5th week of pregnancy.
The main role of the yolk sac is a bridge for the transfer of nutrients between the embryo and the mother. Under normal circumstances, the yolk sac will appear after 5 weeks of pregnancy, and will continue to increase in size during the period of 5-11 weeks of pregnancy, and then gradually decrease in size and disappear after 12 weeks of pregnancy.
When the yolk sac appears, the fetal heart and buds will soon appear, usually about seven days after the appearance of the yolk sac. Therefore, if you go to the hospital for an ultrasound examination after six weeks of pregnancy, you can see the gestational sac, the yolk sac, the fetal heart, and the fetal buds in the uterine cavity, which will help you make a clear diagnosis of the state of pregnancy.
After the yolk sac is seen in the sac, intrauterine pregnancy has been diagnosed, and it is best to take a further ultrasound examination at about eight weeks of pregnancy to confirm whether the fetus is healthy and developing. If you have lower abdominal pain or vaginal bleeding, you need to go to the hospital in time.