Xiao Hui is a professional woman who was busy with her career and did not get pregnant until she was 30 years old. Her pregnancy checkups were normal, but at 32 weeks of pregnancy, she found that her weight and abdominal circumference had not increased much for a month. Let’s listen to the doctor’s answer: Xiao Hui: Doctor, what is amniotic fluid? How is it formed? Doctor: Amniotic fluid is the fluid in the amniotic cavity of the uterus during pregnancy, which is the internal environment necessary for the growth and development of the fetus, just like a fish cannot live without water, it provides a constant temperature and pressure environment for the fetus to grow and move around, and can promote the development of the fetus’ muscles, bones and other organs, as well as protect the fetus from the mechanical damage and contraction pressure of the external environment. Amniotic fluid is mainly formed by the dialysate of maternal serum entering the amniotic cavity through the placenta and fetal membranes before 12 weeks of gestation, but after 12 weeks of gestation, fetal urine and lung fluid are the main sources. The production, absorption and transit of amniotic fluid are coordinated by the mother, fetus, placenta and fetal membranes, and are in a dynamic balance. Any factor that causes an imbalance in the production and absorption of amniotic fluid can cause an abnormal amount of amniotic fluid, resulting in too much or too little amniotic fluid. Xiao Hui: What is the danger of low amniotic fluid to the fetus? Doctor: When the amount of amniotic fluid is less than 300ml, we call it amniotic fluid hypohydramnios, the incidence of which is 0.4-4.0% in China and 0.5-5.5% in foreign countries. Low amniotic fluid can lead to intrauterine distress, pulmonary dysplasia, skeletal malformation, intrauterine growth restriction, premature rupture of membranes, preterm delivery and other complications. If the amount of amniotic fluid is less than 50ml, the incidence of fetal distress is more than 50% and the perinatal mortality rate is 88%. Xiao Hui: What are the causes of low amniotic fluid? Doctor: It is believed that the main factors leading to low amniotic fluid are fetal, maternal and placental factors. The main fetal factors are: twin fetus transfusion syndrome, fetal malformation (such as urinary system malformation), chromosomal abnormalities, diaphragmatic hernia, tetralogy of Fallot, hypothyroidism, intrauterine growth restriction, intrauterine infection, etc.; maternal factors: hypertension, dehydration, blood viscosity, medication, etc.; placental membrane factors: placental hypofunction, overdue pregnancy, premature rupture of membranes, umbilical cord encirclement, umbilical cord malformation, etc. Xiao Hui: How to diagnose low amniotic fluid? Doctor: The diagnosis of abnormal amniotic fluid volume mainly relies on prenatal ultrasound, and the standard adopted in China is that the maximum depth of amnioticfluid volume (AFV) ≤ 50px is considered as low amniotic fluid, and ≤ 25px is considered as severe amniotic fluid. Aminotic fluid index (AFI) ≤125px is considered as low amniotic fluid and ≤200px as low amniotic fluid. Amniotic fluid that occurs after 34 weeks of gestation is called late amniotic fluid hypohydramnios, while the opposite is called early amniotic fluid hypohydramnios. Xiao Hui: What should I do now? Doctor: 1. We have to find the cause of low amniotic fluid, rule out fetal malformations by 3D ultrasound, and if necessary, perform MRI to further check the fetal urinary system and lung development. If there is a combination of serious urinary system anomalies, you need to consider carefully whether to keep the fetus after full consultation on the prognosis of the fetus and whether treatment is feasible. 2. Fetal chromosomal abnormalities and intrauterine infections may exist in low amniotic fluid, and fetal cord blood test is recommended. If the above factors are ruled out, you should have your blood lipids, coagulation function, anti-cardiolipin antibody and other tests, and if there is any abnormality, you should have symptomatic treatment. 1-2 weeks of regular ultrasound monitoring of amniotic fluid, fetal growth and development, umbilical blood flow, placental thickness and size, and fetal electronic monitoring and placental function measurement, if intrauterine distress is found, you should choose to terminate the pregnancy. 4. For patients with low amniotic fluid, we recommend hospitalization for maternal-fetal monitoring and rehydration therapy to improve placental perfusion and increase amniotic fluid volume. Xiao Hui: What is the procedure of amniocentesis? Doctor: The procedure is not complicated and does not require anesthesia. After skin disinfection, we will ultrasonically locate the puncture site, then puncture and extract the amniotic fluid LB to detect the maturity of fetal lung, enter 37℃ amniotic fluid replacement fluid (saline, Ringer’s fluid, etc.), stop the infusion after the amniotic fluid dark area AFV>75px or amniotic fluid index AFI>200px, if the fetal lung is not mature, intrauterine infusion of dexamethasone, postoperative routine administration of The procedure takes 5-10 minutes. Since any interventional prenatal examination carries certain risks, the risk of preterm delivery for this procedure is 5% and hospitalization is recommended before performing this procedure.