What is a subchorionic hematoma?

Pregnant women will encounter many problems during pregnancy. We know that there will be pregnancy reactions from the early stages of pregnancy. Some pregnant women will experience vomiting, nausea, general weakness, and inability to sleep and rest. Therefore, pregnant women may experience weight loss in the early stages, but it doesn’t matter, this is all normal. However, some abnormal problems may occur, such as subchorionic hematoma, but what is subchorionic hematoma? Many first-time pregnant women don’t know much about it. So let’s find out!

The development of the villi increases the contact surface with the uterine decidua, which is beneficial to the exchange of substances between the embryo and the mother. At the end of the second week or the beginning of the third week of embryonic development, the embryonic mesoderm gradually extends into the chorionic villus shaft and is renamed the secondary chorionic villus shaft. Around the end of the third week, the mesenchyme within the villi differentiates into connective tissue and capillaries, forming the tertiary villus trunk. At this point, the trophoblast and extraembryonic mesoderm have developed into a complete chorion. The villus trunk then branches out into many small villi.

At the same time, the cytotrophoblast cells at the end of the chorionic shaft proliferate and penetrate through the end of the chorionic shaft to reach the decidua tissue, fixing the chorionic shaft to the decidua. These cytotrophoblastic cells also extend along the decidua to form a cytotrophoblastic shell.

Make the chorion and endometrium firmly connected. At four weeks of pregnancy, a layer of fibrin deposition called the Nitabuch layer appears between the cytotrophoblast shell and the decidua. The gaps between the villi are called the intervillous spaces, which are filled with maternal blood from the uterine spiral arteries. The embryo absorbs nutrients from the maternal blood and excretes metabolic waste through the villi. The chorion also has endocrine and barrier functions. At 12 weeks of pregnancy, the fibrin-like substance at the bottom of the intervillous space and around the fixed villi is called Rohr stria.

In the early embryonic stage, the villi are evenly distributed on the entire surface of the chorion. As the embryo grows, the villi adjacent to the basal decidua become luxuriant due to rich nutrition and adequate blood supply. This is called chorionic plexus, which constitutes the fetal part of the placenta. The villi adjacent to the decidua gradually degenerate due to lack of blood supply and nutrition, and are called smooth chorion. As the fetus grows and the amniotic cavity continues to expand, the amnion, smooth chorion and decidua capsula further protrude into the uterine cavity and eventually fuse with the parietal decidua. The extraembryonic body cavity and uterine cavity disappear, and only the amniotic cavity remains in the uterus.

The above is the problem about subchorionic hematoma. Knowing this problem will affect the normal development of the fetus. Therefore, pregnant women need to be careful not to let such problems happen easily, and they should go to a regular hospital for regular prenatal checkups. In severe cases, subchorionic hematoma can lead to miscarriage, so pregnant women in the early stages of pregnancy should take timely prevention measures.