For pregnant women, the body is constantly changing, especially for the belly where the fetus is mainly concentrated, and the changes that occur are the greatest. In addition to the fetus, there is also amniotic fluid in the belly, which wraps around the fetus and plays a protective role. Below, the editor will take you to pay attention to a question: the reason for excessive amniotic fluid in fetuses.
Reasons for fetal polyhydramnios
1. Fetal malformation: 18% -40% of pregnant women with polyhydramnios have fetal malformation. Neural tube defects are the most common, accounting for about 50%, with open neural tube malformations being the main cause. When there is anencephaly or overt spina bifida, the exposed meninges of the brain, choroidal tissue hyperplasia, increased exudation, as well as central swallowing disorders and lack of antidiuretic hormone, lead to excessive amniotic fluid formation and reduced reflux; Fetal esophageal and duodenal atresia can cause difficulties in swallowing amniotic fluid, leading to polyhydramnios.
2. Chromosomal abnormalities: fetuses with trisomy 18, trisomy 21, and trisomy 13 may experience difficulty swallowing amniotic fluid, leading to polyhydramnios.
3. Twin pregnancy: About 12% of twin pregnancies are complicated by polyhydramnios, which is more than 10 times that of singleton pregnancies. When there is a single egg, single chorionic villi, and double amniotic sac, the two placental arteries and veins anastomose, which can easily lead to twin transfusion syndrome, increased circulating blood volume in the affected fetus, increased fetal urine volume, and cause polyhydramnios.
4. Pregnancy complicated with diabetes: maternal hyperglycemia leads to increased fetal blood sugar, resulting in osmotic diuresis, and increased placental and fetal membrane exudation leading to excess amniotic fluid.
5. Fetal edema: polyhydramnios is related to immune edema (such as hemolysis due to maternal fetal blood type incompatibility) and non immune edema (often caused by intrauterine infection) of the fetus.
6. Placental and umbilical cord lesions: Giant placenta and umbilical cord sail like attachment can lead to polyhydramnios. When the diameter of placental villous hemangioma is greater than 1cm, 15% -30% may be accompanied by polyhydramnios.
7. Idiopathic polyhydramnios: accounting for about 30%, without accompanying abnormalities in the pregnant woman, fetus, or placenta. The reason is unknown.
Symptoms of polyhydramnios
1. Chronic polyhydramnios: more common. It often occurs between 28-32 weeks of pregnancy. The specific manifestation is a slow increase in amniotic fluid within a few weeks, accompanied by mild compression symptoms or no symptoms. Most pregnant women can gradually adapt, but they only feel a rapid increase in abdominal size. Upon examination, it was found that the uterine tension was high, the uterine height and abdominal circumference were greater than those during the same period of pregnancy, there was a significant sensation of fluid tremors, the fetal position could still be clarified or unclear, and the fetal heart sounds were distant or inaudible.
2. Acute polyhydramnios: rare. It often occurs between 20-24 weeks of pregnancy, with a sudden increase in amniotic fluid and a significant enlargement of the uterus within a few days. The patient feels bloating and pain in the abdomen, soreness in the waist, and difficulty moving around. The skin is tight and shiny, and breathing difficulties and even cyanosis are caused by the elevation of the transverse septum, making it impossible to lie flat. Examination shows high abdominal distension, high skin tension, thinning, dilation of the inferior abdominal veins, and may be accompanied by varicose veins and edema in the external genitalia; The uterus is larger than the gestational month, has high tension, the fetus cannot be examined clearly, and the fetal heart sounds are distant or inaudible.
The above is the information compiled by the editor on the reasons for excessive amniotic fluid in fetuses. During pregnancy check ups, pregnant women must pay attention to changes in some physical substances, such as the amount of amniotic fluid, which can also affect the growth of the fetus to a certain extent and even lead to more serious consequences. Therefore, pregnant women are very fragile and need to pay more attention.
