After pregnancy, I have not found the yolk sac. What is the situation? If I don't see the yolk sac, does it mean I am not pregnant?

Generally speaking, a yolk sac will form in the uterus about three weeks after pregnancy. It can be said that the yolk sac is a preparation for the development of the fetal heart and embryo bud. The yolk sac can be seen in the pregnancy checkup one month after pregnancy, but there are also cases where the yolk sac is not seen in the early pregnancy.

What if I can't find the yolk sac after I get pregnant?

For women with regular menstrual cycles, vaginal ultrasound can generally reveal a gestational sac in the uterine cavity around 35-38 days after pregnancy, and a yolk sac can be seen around 40 days. The yolk sac is a specific indicator of intrauterine pregnancy, and the discovery of a yolk sac indicates an intrauterine pregnancy.

Generally, after the yolk sac is formed, the embryo will gradually grow, and the embryo heart tube can be seen beating around the 45th day of pregnancy. Of course, the actual pregnancy may not strictly follow this standard, because different women have different menstrual cycles.

For women with irregular menstrual cycles, or women who become pregnant through ovulation induction treatment, the time to see the yolk sac and embryonic heart tube pulsation will also vary due to the early or uncertain occurrence of ovulation. In clinical practice, we have encountered the latest discovery of fetal heartbeats after more than 60 days of amenorrhea from the last menstrual period, so there are great individual differences.

For example, if you are still around 40 days pregnant, it is OK to see the yolk sac, and you need to understand the size of the yolk sac and gestational sac. If the gestational sac is larger than 2.5 cm and you haven’t seen the embryo or fetal heartbeat for a week, then the probability of fetal arrest is relatively high, so you should not only observe the presence of the yolk sac, but also the gestational sac.

In addition, blood indicators should also be checked to indirectly understand the development of the embryo. If the blood indicators are good, then just continue to observe. If the blood indicators are not good, such as HCG rising slowly or decreasing, it also indicates that the embryo is not developing well.

In general, in addition to ultrasound examination to comprehensively evaluate the development of the embryo, the above analysis is for reference only.

No yolk sac is not seen, does it mean that you are not pregnant?

No yolk sac is seen, which means that the yolk sac is not observed under B-ultrasound in the early pregnancy. This situation may occur before 5 weeks of pregnancy.

In early pregnancy, the gestational sac develops first, followed by the yolk sac. However, in the early stage, because the gestational sac is too small, about 2 or 3 mm, it is impossible to confirm whether it is the gestational sac or the cystic echo caused by intracavitary hemorrhage, so the yolk sac is used as a sign of early pregnancy.

As for the absence of yolk sac as described in the ultrasound report, if it is around 40 days in the early pregnancy, it is only because the gestational sac is too small and the yolk sac has not grown yet, or the current size cannot be displayed under the ultrasound setting. It is impossible to confirm whether you are really pregnant. In another case, if the yolk sac is still not seen after more than 50 days of early pregnancy, then the possibility of an empty gestational sac is relatively high. At this time, the blood HCG and progesterone values ​​should be rechecked to confirm the diagnosis.

Why is the yolk sac not seen in early pregnancy?

The yolk sac is a mass of sac tissue with rich blood vessels inside the gestational sac, which is formed as early as 3 weeks of pregnancy.

The main function of the yolk sac is to store and provide nutrients for the early embryo. It continues to grow as the embryo develops until it gradually loses its function at 10-12 weeks of pregnancy, and then slowly shrinks and disappears. By 20 weeks of pregnancy, the yolk sac is no longer visible.

There are three situations in which the yolk sac is not seen in early pregnancy:

1. If the gestational age is earlier than 5 weeks, the yolk sac is too small to be seen by B-ultrasound.

2. Irregular ovulation period leads to deviation in the estimation of gestational age.

3. Empty gestational sac and fetal arrest.