Evaluation of amniotic fluid volume by fetal ultrasound

The article was professionally consulted by Specialist Doctor I Le Hong Lien - Department of Obstetrics and Gynecology - Vinmec Central Park International General Hospital.

1.1. Amniotic fluid origin Amniotic fluid is derived from maternal serum: the concentration of solutes in amniotic fluid is similar to that of solutes in maternal serum.
The volume of amniotic fluid gradually increases towards the end of pregnancy to reach about 1000 ml
1.2. Amniotic fluid volume Fetal amniotic fluid ultrasound to check the assessed volume accurately to help mothers monitor the amniotic fluid index well to avoid complications during pregnancy:
Volume Amniotic fluid increases gradually with gestational age to about 32 weeks, which is constant. From week 32 amniotic fluid is constant at about 700ml-800ml. After 42 weeks tapered off at the rate of 8%/week. The limit has a smaller range of variation than the upper limit of pregnancy in the third trimester. oligohydramnios is defined as less than 300ml. Polyhydramnios is defined as over 1700ml.

Amniotic fluid measurement via ultrasound is done on the baby. It's a standard way to check your baby's health. Your doctor will also do this test in your physiologic record.

Amniotic fluid surrounds the baby in your belly. It cushions your baby, and helps your baby's lungs, digestive system, and muscles develop. While you're pregnant, your doctor will monitor your amniotic fluid levels. If they're too low or too high, you're more likely to have complications, such as premature birth. This also means there is a problem with the baby or the placenta. During a normal ultrasound, your doctor or ultrasound technician will check your amniotic fluid levels. There are several ways to estimate amniotic fluid volume. These include the amniotic fluid index (AFI) to assess the amount of amniotic fluid and measure the depth of the sac.
Amniotic fluid index, symbol AFI (Amniotic fluid index) is a parameter about the amount of amniotic fluid present in the abdomen of a pregnant woman at each stage of fetal development. Amniotic fluid index is measured when pregnant women go to the doctor, based on this index, the doctor will tell the mother whether the amount of amniotic fluid is normal or abnormal (polyhydramnios, oligohydramnios, amniotic fluid,...)

The sonographer will estimate your amniotic fluid volume by measuring the amniotic cavity during the ultrasound. There is no risk to you or your baby.

Low amniotic fluid levels are at risk early in your pregnancy. They can be a sign that your baby is growing too slowly. If it occurs late in pregnancy, it could be a sign of placental failure. Your doctor may want to monitor your pregnancy more closely.
A high amount of amniotic fluid usually doesn't cause problems. But high levels increase the risk of premature birth or growth problems. You may need more frequent ultrasounds. The antenatal care doctor will advise on an appropriate diet to limit the increase in amniotic fluid

Your doctor or technician will check your amniotic fluid whenever you have an ultrasound. If you have problems during your pregnancy, you may need more frequent ultrasounds.
Vinmec International General Hospital offers a Package Maternity Care Program for pregnant women right from the first months of pregnancy with a full range of antenatal care visits, periodical 3D and 4D ultrasounds and routine tests to ensure that the mother is healthy and the fetus is developing comprehensively. Pregnant women will be consulted and checked for health under the close supervision of experienced and specialized obstetricians, helping mothers gain more knowledge to protect their health during pregnancy as well as minimize complications affecting mother and child.
Specialist I Le Hong Lien has been an obstetrician-gynecologist at Vinmec Central Park International Hospital since November 2016. Doctor Lien has over 10 years of experience as a radiologist in the Department of Ultrasound at the leading hospital in the field of obstetrics and gynecology in the South - Tu Du Hospital.