Amniotic fluid is the fluid inside the amniotic cavity, the “ocean” that nurtures the growth and development of the fetus. During the fetal period, everyone grows up immersed in the mother’s amniotic fluid. October pregnancy, amniotic membrane puncture, amniotic fluid leakage, ushered in a day of delivery.
1, the amniotic fluid “origin”
Where does amniotic fluid come from and why is it called “amniotic fluid”?
In fact, on the seventh or eighth day of development of the fertilized egg, the cellular nourishment of the stratification of the amniotic membrane, but also from the ectoderm of the fetus is constantly expanding. The normal amniotic membrane is only 0.02 to 0.5 mm thick and cannot be seen with the naked eye, and the “amniotic fluid” is the liquid that fills the invisible amniotic membrane.
Amniotic fluid is a pale yellow transparent liquid, composed of 98% water and 2% other substances, including fetal skin and amniotic epithelial debris mixed in during pregnancy, small amounts of inorganic salts and organic hormones. The amniotic fluid in the pregnant mother’s body is constantly exchanged and renewed. In the early stages of pregnancy, the amniotic fluid comes mainly from the penetration of the pregnant mother’s blood plasma, and in the following days it comes mainly from the fetus’ urine. The fetus will produce urine constantly discharged into the amniotic fluid, amniotic fluid is also constantly absorbed by the fetal membrane and swallowed by the fetus, a row and a collection, the balance between the two maintains the amount of amniotic fluid.
2.The role of amniotic fluid
The amniotic fluid in the pregnant mother’s uterus, with the protection of the fetus, so that the fetus can grow safely in a stable pressure and temperature; to protect the fetus from external injury cushioning role, and to prevent the fetus to the amniotic membrane adhesions; to allow the fetus to have a free range of function; to prevent external bacterial infection, and to minimize the harm caused by infection; to late pregnancy, there will often be irregular uterine contractions, can reduce It can reduce the pressure on the fetus during contractions and make the pressure of contractions more even; it can transmit the pressure of the uterine wall during labor; it has the function of dilating the cervical opening; it can smooth the birth canal after the rupture of membranes, reducing the damage to the mother and the fetus and facilitating the delivery of the fetus. In addition, amniotic fluid is an indicator to assess the health of the fetus, for example, amniocentesis can determine whether the fetus has congenital anomalies; the oval boron in amniotic fluid will increase as the fetus’ lungs develop, so it is an important indicator to understand the development of the fetus’ lungs. Although the amniotic fluid is the fetal baby’s good friend, good guard, but it can also have a bad “good” time, and may even become a “disaster water”.
3, too little amniotic fluid
Usually the water volume of a full-term mother-to-be is 400 to 1500 ml, when the amniotic fluid is less than 300 ml, it is amniotic fluid hypohydramnios. During the examination, it can be found that the abdomen of the pregnant woman is smaller than that of the same pregnancy, the abdomen is tighter, the feeling of vibration when there is amniotic fluid is missing, and the average amount of amniotic fluid is less than 2 cm during the ultrasound examination, and hypoamniotic fluid can be diagnosed. The main causes are: fetal abnormalities and dysplasia, which can be accompanied by malformations of the fetal urinary system, such as fetal congenital renal agenesis, congenital renal dysplasia, etc. Fetal urine is reduced, making the source of amniotic fluid insufficient; secondly, overdue pregnancy, fetal growth retardation, and amniotic membrane lesions can also cause low amniotic fluid.
Due to low amniotic fluid, the fetus loses the cushioning and protective effect of amniotic fluid, and the fetal activity is also restricted, and abnormalities of fetal heartbeat also easily occur. If low amniotic fluid occurs in the middle of pregnancy, adhesions can occur in the amniotic cavity and form adhesive bands, which can cause fetal body curvature and adhesions of the limbs, which can cause oblique neck, foot exstrophy and lung hypoplasia in the middle of pregnancy. If low amniotic fluid occurs in late pregnancy, it often causes the umbilical cord to be compressed, causing the fetus to suffer from hypoxia. At the time of delivery, the lack of amniotic fluid forming the anterior amniotic sac cannot effectively compress the cervix, making the cervix dilate slowly and causing fetal hypoxia and asphyxia during labor. Low amniotic fluid is an important sign of fetal risk if it occurs in late pregnancy or intrauterine growth retardation. It should be taken very seriously.
When low amniotic fluid is found during prenatal examination, special attention should be paid to the presence of fetal malformations on the one hand, and to the presence of fetal growth retardation, overdue pregnancy or the occurrence of umbilical cord compression when low amniotic fluid is present. The presence of low amniotic fluid indicates that the fetus is at risk and needs to be monitored by fetal heartbeat, fetal movement and ultrasound. If the amniotic fluid is too low, you can take the treatment plan of drinking more water and “amniotic fluid infusion”, in which saline is infused into the amniotic cavity, and if the amniotic fluid decreases sharply during full-term delivery, you should exclude the possibility of intrauterine distress and perform cesarean section if necessary; if fetal abnormalities are found, early termination of pregnancy is recommended.
4. Excessive amniotic fluid
As the pregnancy progresses, the amount of amniotic fluid gradually increases. At 16 weeks of gestation, the amniotic fluid is about 250 ml, at full term, the amniotic fluid can reach 400-1200 ml, at more than 40 weeks of gestation, the amniotic fluid decreases by about 1/3 of the amount. If the amount of amniotic fluid exceeds 2000 ml during pregnancy, the amniotic fluid is excessive. In a few cases, the amniotic fluid volume increases sharply within a few days, which is acute amniotic fluid overload, and in most cases, the amniotic fluid volume increases slowly, which is chronic amniotic fluid overload. The diagnosis of excessive amniotic fluid can be established when the pregnant woman’s abdomen is too large and distended, and the average amniotic fluid volume measured by ultrasound exceeds 8 cm.
The causes of excessive amniotic fluid are both from the mother’s own causes and from the fetus, the most common of which is the mother-to-be suffering from diabetes. The most common cause is the mother’s diabetes mellitus, because diabetes mellitus can cause diuresis in the fetus due to high blood sugar, which in turn can cause excessive amniotic fluid, so only the mother’s blood sugar can be controlled. In addition, maternal and fetal blood group incompatibility and multiple pregnancies can also have excessive amniotic fluid. Fetal causes such as open central nervous system anomalies such as anencephaly and cremasteric cleft, digestive system anomalies such as esophageal or intestinal atresia, and circulatory disorders can all cause excessive amniotic fluid. Amniotic fluid overload can cause many complications, such as difficulty in breathing, inability to lie down, abdominal distension and pain, significant edema in the lower extremities, and often gestational hypertension and fetal position abnormalities. Premature rupture of membranes and preterm delivery can also occur when there is too much amniotic fluid. Because the uterus is too large, the contraction of the uterus is poor and postpartum hemorrhage is likely to occur.
If excessive amniotic fluid is found during prenatal examination, the cause should be carefully identified, such as the presence of fetal abnormalities and the presence of diabetes in the pregnant woman. If the condition is serious, amniocentesis can be considered to release excessive amniotic fluid; if excessive amniotic fluid is found in early pregnancy due to fetal abnormalities, termination of pregnancy should be considered.
5.amniotic fluid embolism
Amniotic fluid embolism is a syndrome in which amniotic fluid enters the mother’s blood circulation during delivery, causing a series of critical symptoms such as pulmonary embolism and shock. The condition of amniotic fluid embolism is extremely dangerous and terrible, it often puts the mother to death in an instant, with a mortality rate of more than 80%, of which 50% die within one hour. Therefore, it is called the fatal killer of pregnant mothers. Amniotic fluid embolism is triggered by many reasons. Multiple births, contractions too strong and too frequent, amniotic fluid contaminated by meconium, or normal delivery, midterm induction of labor, large month miscarriage, cesarean section, etc., all have the opportunity to make the amniotic fluid squeeze into the pregnant mother’s blood circulation.
Once this disease occurs, resuscitation treatment is extremely difficult and requires the cooperation of obstetricians, physicians, surgeons and anesthesiologists. Routine management includes a combination of positive pressure oxygenation, release of pulmonary and bronchial spasm, anti-shock, anti-allergy, correction of coagulation disorders, prevention and treatment of renal failure, and rapid termination of pregnancy. Early diagnosis, effective measures, resuscitation conditions and personnel quality are closely related to the success of resuscitation.
Prevention of amniotic fluid embolism is extremely important, and the following points should be noted.
(1) During delivery, use oxytocin rationally to avoid the occurrence of too strong contractions; prevent inappropriate uterine operations and damage to the uterus and birth canal.
(2) During delivery of the fetus, do not press hard on the abdomen and uterus to prevent the amniotic fluid from being pressed into the mother’s blood.
(3) Manual rupture of membranes should be performed in between contractions and attention should be paid to let the amniotic fluid flow slowly. When midterm pregnancy is induced by clamping, the action should be gentle and accurate to avoid the occurrence of amniotic fluid embolism.
(4) Strictly grasp the indications for cesarean delivery. After cutting open the uterus, pressure should be applied around the incision and the amniotic fluid should be aspirated to prevent the amniotic fluid from entering the mother’s blood at the incision. Be highly alert to pathological pregnancies with twin fetuses, giant babies, placenta abruptio, placenta praevia, etc. where amniotic fluid can easily enter the mother’s blood.