The amount of normal amniotic fluid varies with different stages of pregnancy. The amniotic fluid volume gradually increases from about 200 milliliters at 16 weeks of pregnancy to 980 milliliters at 34-35 weeks of pregnancy; Afterwards, the amniotic fluid gradually decreased, reaching about 800 milliliters at 40 weeks. The amniotic fluid in expired pregnancy is significantly reduced, and can be reduced to below 300ml. Late pregnancy with less than 300 milliliters of amniotic fluid is called oligohydramnios.
Oligohydramnios seriously affects the prognosis of babies, with a amniotic fluid volume of less than 50ml and a perinatal mortality rate of up to 88%. The main causes of oligohydramnios are fetal malformations (mainly urinary system malformations, such as fetal kidney deficiency, chromosomal abnormalities, etc.); Decreased placental function (such as post term pregnancy); Amniotic membrane leakage caused by premature rupture of membranes; Pregnant women with hypertension, dehydration, and taking certain medications such as indomethacin orally can also lead to oligohydramnios. Oligohydramnios endangers the life safety of babies. How to detect oligohydramnios early and how to deal with it?
How to detect oligohydramnios?
Mainly relying on production inspection
Most pregnant women with oligohydramnios generally do not experience significant discomfort, so it is usually discovered during prenatal checkups by doctors or ultrasound examinations. Some pregnant women may experience abdominal pain during fetal movement, and placental dysfunction often leads to reduced fetal movement, a feeling of tight uterus wrapping around the fetus, and uterine sensitivity. Mild stimulation such as fetal movement can easily cause uterine contractions. Sometimes a fetal movement can cause significant abdominal pain. This is due to the loss of the buffering effect of amniotic fluid, and the force of fetal movement directly acts on the local uterine wall to stimulate uterine contractions.
Some pregnant women may have vaginal discharge or intermittent small amounts of watery secretions, often due to premature rupture of membranes. During prenatal check ups, it is often found that the uterine height and abdominal circumference are smaller than the corresponding gestational age, and the presence of fetal growth restriction is more pronounced. At this point, doctors often recommend pregnant women to undergo ultrasound to estimate the amount of amniotic fluid.
These commonly used ultrasound data are worth collecting. In late pregnancy, if the maximum vertical depth of the dark zone (AFV) of amniotic fluid is ≤ 2cm, it is considered oligohydramnios 2cm is considered severe oligohydramnios. Amniotic fluid index (AFI) ≤ 5cm indicates oligohydramnios, ≤ 8cm indicates oligohydramnios.
