What is the normal value of amniotic fluid depth at 20 weeks of pregnancy

During pregnancy, the fetus is conceived in the amniotic fluid of the pregnant mother. With the advancement of pregnancy months, the depth of the amniotic fluid inside the uterus will also change to a certain extent. Any abnormality in the amniotic fluid will immediately cause abnormality in the fetus. In severe cases, it may even cause the fetus to die from lack of oxygen. So how much amniotic fluid is normal for a woman in the 20th week of pregnancy? Let's take a look!

How much amniotic fluid is there in a 20-week pregnancy?

The amniotic fluid of a pregnant woman at 20 weeks of pregnancy is 4.55cm, and the standard deviation is 0.74cm. The amniotic fluid in the pregnant woman's uterine cavity has the regulatory function of protecting the fetus from harm by outsiders. It can also maintain a suitable temperature in the uterine cavity and allow the fetus to have space to move freely. It is very important for pregnant women.

If the depth of amniotic fluid is ≥8cm, it means that there is too much amniotic fluid. The effects of too much amniotic fluid on pregnant women mainly include placental abruption, uterine atony, postpartum hemorrhage, etc. Due to excessive amniotic fluid, the fetus has a large range of motion in the uterine cavity, which can easily lead to a transverse position of the fetus; excessive swelling of the uterus and excessive pressure can easily lead to premature birth.

If the amniotic fluid of the pregnant woman is discharged after rupture of the membrane, resulting in a decrease in the pressure in the uterine cavity, it may cause early embryo separation. In addition, the pregnant woman's uterus is large, and excessive expansion can easily cause uterine atony, and may also cause the risk of postpartum hemorrhage, all of which have a great impact on the pregnant woman and the fetus.

If the depth of amniotic fluid is ≤2cm, it means that there is too little amniotic fluid. The impact of too little amniotic fluid on the fetus is mainly to increase the perinatal mortality rate, which will cause fetal intrauterine dysplasia, deformity and lack of oxygen. The impact on pregnant women is that it increases the probability of caesarean section.

What amniotic fluid index should be checked during pregnancy?

Amniotic fluid depth: It is the vertical depth of the amniotic fluid reservoir examined by B-ultrasound. Generally speaking, an amniotic fluid depth (AFV) of 3-7cm is a normal amniotic fluid flow, ≤2cm indicates too little amniotic fluid, and ≥8cm indicates too much amniotic fluid. It is a medical term and a key indicator to determine the amount of amniotic fluid in a pregnant woman.

Amniotic fluid index: The uterus is divided into four quadrants: upper left, upper right, lower left and lower right. The sum of the vertical depths of the largest dark areas of amniotic fluid in the four quadrants is the amniotic fluid index. Generally, the amniotic fluid index of 9-24cm is a normal amniotic fluid flow.

If the amniotic fluid index is ≥25cm, it is diagnosed as polyhydramnios. Among them, the amniotic fluid index (AFI) of 25-35cm is mild polyhydramnios, and 36-45cm is mild to moderate polyhydramnios.