Why does a velamentous placenta form?

How does a velamentous placenta occur? Many pregnant women find out that they have velamentous placenta when they go for prenatal check-ups in the late stages of pregnancy. It is important to understand that velamentous placenta is a psychologically distorted condition that causes great harm to both the fetus and the pregnant woman. So how does a velamentous placenta occur?

What causes velamentous placenta?

1. What causes velamentous placenta?

At present, the cause of velamentous placenta is unclear, and there are many assumptions or theories. The embryo is an organ that is very sensitive to blood supply. When the blood supply to the embryo attachment site is reduced due to various factors (such as a history of caesarean section or multiple miscarriages, resulting in damage, inflammation or shrinkage of the uterine wall), the embryo begins a process of slow migration to the blood-rich area, leaving the helpless fetal umbilical cord behind. Although it is painful to separate, the entanglement is unclear. The connection is the placenta. The fetal umbilical cord blood vessels distributed in the placenta are extremely sensitive and fragile due to the lack of protection from a special structure (Wharton's jelly). They will flatten when subjected to force and break when pulled, which will cause very serious adverse effects, the most serious of which may cause the death of the fetus.

What causes velamentous placenta?

2. What is a velamentous placenta?

Velamentous placenta is actually a fetal umbilical cord disease, which should be called fetal umbilical cord velamentous adhesion or velamentous insertion, which is very rare. However, its incidence rate has been gradually increasing: it is related to the opening of the two-child policy, the development of ovulation induction technology (in vitro fertilization or IVF, etc.), and the abuse of intrauterine operations (abortion, hysteroscopy, etc.). As medical knowledge of the disease increases and corresponding detection technologies develop rapidly, the detection rate of the disease has increased.

3. What are the harms of velamentous placenta?

The umbilical vessels of the velamentous placenta have already formed branches before entering the embryo, and enter the embryo through the placenta and hcg, and enter the embryo in a fan-shaped pattern. The incidence of velamentous placenta in twins is 10 times higher than that in singletons, because the fetal umbilical cord vessels of the velamentous placenta are attached to the placenta. If the placenta ruptures, the fetal umbilical cord vessels will rupture and cause bleeding, which will cause the death of the fetus within a few minutes. However, this situation is not common. If the velamentous fetal umbilical cord is inserted and the blood vessels are located at or close to the cervical opening, which is the externalized blood vessels often prompted by B-ultrasound, the probability of vascular rupture will be greater. Therefore, under normal circumstances, if the velamentous fetal umbilical cord is only inserted and there is a simple velamentous placenta without externalized umbilical vessels, the probability of vascular rupture is low.

Although a velamentous placenta is not as scary as everyone imagines, it still needs to be taken seriously. The blood vessels of such an embryo are attached to the placenta and are relatively superficial, which makes it easy for kinks and stress to occur, resulting in reduced blood supply to the fetus and changes in the fetal heartbeat. If this condition persists, it may cause fetal intrauterine hypoxia or even death. In addition, if the fetal umbilical cord attachment point happens to be at the outer edge of the embryo close to the cervix, it may also be compressed by the fetal presenting part, causing harm to the fetus.

What are the tests for velamentous placenta?

1. General pregnancy check-up

When there are twins, polyhydramnios, B-ultrasound shows lobed or multi-lobed embryos, vaginal bleeding accompanied by fetal distress, and fetal heart rate changes are sinusoidal, attention should be paid to the possibility of this disease. During vaginal examination, fine, non-dragful cord-like substances may be felt on the placenta, but a positive result is unlikely when the cervix is ​​not dilated. If the abdominal distension is obvious, it may be considered to perform upper artificial rupture of membranes in the early stage. If bloody amniotic fluid appears and fetal distress occurs quickly, other than embryonic factors, the possibility of this disease should also be considered.

What causes velamentous placenta?

2. Color Doppler Ultrasound Imaging

Observing the fetal blood, blood vessel shape and fetal adhesion has made it possible to detect the velamentous adhesion of the fetal umbilical cord during prenatal examination. In addition, intravaginal ultrasound can directly observe the shape of vasa previa on the placenta, which is also of great help in early and direct diagnosis, and there have been successful reports.

3. Amnioscopic

The vasa previa on the placenta and turbid amniotic fluid of the pregnant woman can be observed immediately, but there is a concern about damage to the blood vessels.

4. Collect vaginal bleeding to assess the source of bleeding

The common methods are as follows: acid-fast staining for Wright staining, searching for fetal nucleated red blood cells under a microscope; taking samples for hemoglobin electrophoresis, if the hemoglobin concentration F is found, it reminds the pregnant woman that the amniotic fluid is stained with fetal blood; Apt-Downey experiment: adding sodium hydroxide solution to the sample, if it is still bright red, the bleeding comes from the fetus, if it is dark brown, it is maternal blood; Kleihauer-Betke experiment: adding weak acid to the sample and doing a special coloring and then acid-fast staining smear, the mother's blood cells are not colored with hemoglobin and break into "phantom cells", while the fetal blood cells remain unchanged and show bright red. This method can quantitatively estimate the amount of fetal blood loss.

What to do if you have a velamentous placenta

Because the cause of velamentous placenta is not very clear in clinical medicine at present, there may be no way to treat the condition in an intuitive way, but we can consider that the occurrence of this disease is related to a low-lying placenta in early pregnancy. By estimating the progress of pregnancy, understanding the development of the uterus with rich blood supply to the embryo, and then discovering that the placenta in the center will gradually change into a velamentous placenta. Of course, these symptoms also need to be clarified. But we can also consider various reasons, such as intrauterine infection, malformed fetus, intrauterine reflex factors, etc., which may cause the formation of velamentous placenta. Therefore, what we need to be concerned about is not only the survival rate of the baby, but also the treatment plan.

What causes velamentous placenta?

The velamentous placenta actually has little to do with the baby's survival rate, so there is no question of how much the survival rate is. However, when the vasa previa on the velamentous placenta ruptures, it will cause the death of the fetus. If it does not rupture, there will be no significant effect. This is a simple rupture and the chance of rupture. Under normal circumstances, if the velamentous placenta can be treated in time, the possibility of rupture will reach 50%. If the best time for treatment is delayed, the possibility of rupture will reach about 60%. Only timely treatment of the disease is the most important factor in saving the baby.