What causes irregular size of gestational sac?

Many pregnant women will be told by their doctors that the gestational sac is irregular in size after an ultrasound during pregnancy, and the doctors will also remind them of many problems. This situation is mainly due to the irregularity of the gestational sac, which affects the placental tissue and amniotic fluid membrane and blood vessels, so they cannot develop normally. Therefore, some complications may occur, and the next response needs to be judged based on the characteristics of the disease.

1. Causes of irregular gestational sac

The gestational sac is the primitive placental tissue, a small embryo wrapped by the amniotic membrane and vascular network. The gestational sac is the initial form of pregnancy. At that time, the fetus has not yet formed, and the fetal heartbeat is already there when the embryonic bud appears.

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.

In the second week, the embryo implants in the endometrium. When it develops into the second germ layer, a large cavity called the primary yolk sac appears on the ventral side of the embryonic disc. The yolk sac continues to shrink and degenerate during embryonic development, but the extraembryonic mesoderm on the wall of the yolk sac is the earliest origin of the formation of blood cells, blood vessels and primitive germ cells - the gestational sac, where the fetus will grow in the future.

There are also irregularities in the early development of the fetus. It is recommended not to perform B-ultrasound frequently to avoid affecting the fetus. You can combine the diagnosis with endocrine examination to clarify the fetal development. The gestational sac itself is not very regular during embryonic development, so don't be too nervous about it.