Amniotic fluid embolism (AFE) is one of the leading causes of maternal mortality and a rare and not fully understood obstetric emergency. It is a process in which amniotic fluid, together with fetal cells, hair, and dander, passes through the placenta and enters the maternal circulation during labor, further inducing a strong inflammatory response in the mother.
In the past, the medical community thought that amniotic fluid with these impurities blocked the blood vessels in the lungs, which is why it was called "amniotic fluid embolism" at that time; however, in recent years, research generally does not believe that a simple "embolism" can lead to such a serious result, and that there should be other causative mechanisms.
Types, symptoms, and signs of amniotic fluid embolismClinically, the diagnosis of amniotic fluid embolism can only be made after other diseases have been ruled out.
Amniotic fluid embolism can occur when a mother with no pre-existing cardiopulmonary, seizure, or coagulation problems experiences a sudden onset of the following symptoms and signs: agitation, confusion, followed by a decline in cardiopulmonary function, low blood pressure, shock failure, and seizures.
In "fulminant" amniotic fluid embolism, these symptoms are quickly followed by respiratory distress and cyanosis, a change in the color of the skin or mucous membranes to purple or blue.
Sometimes there is coughing, pink foamy sputum, a drop in blood pressure, and in a few cases there is an instant loss of consciousness, cardiac arrest and death;
In the slow-onset type, the symptoms are milder or not even noticeable, and amniotic fluid embolism is not detected until there is a loss of consciousness, or postpartum hemorrhage where the blood fails to coagulate; and there are also some amniotic fluid embolisms where the onset of hemorrhage is the main manifestation of postpartum hemorrhage, which can be easily recognized. There are also some cases of amniotic fluid embolism, in which the onset of postpartum hemorrhage is the main manifestation, which can be easily mistaken for postpartum hemorrhage caused by weak uterine contractions.
Timing and circumstances of amniotic fluid embolism
It is generally believed that amniotic fluid and fetal sebum and hair enter the mother's body as a result of the following three conditions:
1. Rupture of the uterus or cervix: (In rare cases, this may be due to cesarean section or uterine surgery).
2. Rupture of amniotic fluid: (In rare cases, this may be due to water breakage or amniocentesis).
3. Elevated pressure in the uterus and veins: (In rare cases, this may be due to labor or hypnosis).
These three conditions are usually more likely to occur before or after labor, and in a few cases after delivery. In addition, amniotic fluid embolism can also occur in mothers over 30 years of age who are in labor, and in cesarean sections or induced labor, but the incidence is very low.
2 Amniotic fluid embolism due to amniotic fluid allergy
In the past, it was thought that amniotic fluid embolism was caused by "amniotic fluid or fetal tissue blocking the mother's heart and lungs", but this does not explain "why the mother had rapid cardiopulmonary failure and was unable to clot in a very short period of time.
It is now widely recognized that the amount of amniotic fluid that enters the mother's body is less important than the mother's response to the fluid.
The course of the disease is very similar to that of sudden shock due to drug allergy, which is very rapid and difficult to predict. Therefore, some have renamed amniotic fluid embolism as amniotic fluid hypersensitivity syndrome (AFSS), which is hypothesized to be caused by an allergic reaction in the mother induced by certain fetal secretions, hair, and sebum.
The rapid and violent inflammatory response may lead to a decline in cardiopulmonary function and injury to brain cells; it also disrupts the entire coagulation mechanism because of rapid platelet aggregation, which depletes prothrombin. However, the details of the mechanism of amniotic fluid embolism are not yet conclusive.
3 Does amniocentesis increase the risk of amniotic fluid embolism
Amniocentesis does have the potential to cause amniotic fluid embolism; however, because of the small gestational age of the fetus at the time of amniocentesis, the concentration of fetal lipids and cellular secretions is still very low, and therefore the risk of amniotic fluid embolism is minimal. The vast majority of amniotic fluid embolisms still occur before and after labor.
4 How to improve maternal and infant survival in amniotic fluid embolism
If the disease progresses slowly, there is time for resuscitation and massive blood transfusions.
It requires the cooperation of obstetricians and gynecologists, anesthesiologists, emergency physicians, and pediatricians, as well as a large amount of blood from the blood bank. The entire medical team has to be mobilized in a short period of time, which may improve the survival rate of the mother and baby.
The incidence of amniotic fluid embolism is extremely low, so moms should not worry too much and should still be able to rest in peace. As a precautionary measure, don't switch to a cesarean section for fear of pain unless it is indicated or necessary.