How to do amniotic fluid testing

Amniotic fluid is a very important substance for the fetus. It can effectively protect the fetus and provide a comfortable environment for the growth and development of the fetus. Precisely because amniotic fluid is so important to the fetus and pregnant women, people need to pay special attention to it and check it regularly. Amniocentesis is a common method, so how should it be performed? Let me introduce it in detail below.

The steps for amniocentesis are as follows. Pregnant women who meet the indications should first undergo B-ultrasound to determine the position of the placenta and the condition of the fetus to avoid accidental injury to the placenta. If B-ultrasound is not available, palpation can be used to find areas with large cystic sensation and easy to touch floating fetal body, and the placenta can also be avoided. After selecting the insertion point, disinfect the skin, spread a disinfectant towel, perform local anesthesia, and use a lumbar puncture needle with a needle core to vertically pierce the selected point; there will be two empty sensations when the needle passes through the abdominal wall and uterine wall, and the needle core is removed; use a 2 ml syringe to draw out 2 ml of amniotic fluid and discard it. This section of amniotic fluid may contain maternal cells; then use a 20 ml empty needle to draw out 20 ml of amniotic fluid, and put them into 2 sterile test tubes respectively, and cover them; remove the needle, cover with sterile gauze, press for 2-3 minutes, and the pregnant woman should rest in bed for 2 hours. The removed amniotic fluid is centrifuged for 5 to 10 minutes.

Examination items include cell culture, sex chromosome identification, chromosome karyotype analysis, amniotic fluid alpha-fetoprotein measurement, amniotic fluid biochemical examination, etc., to determine the maturity and health status of the fetus, and to diagnose whether the fetus is normal or has certain genetic diseases. Generally, with ultrasound testing, the risks are minimal and there is no pain.

Amniotic fluid examination can diagnose a variety of fetal malformations and diseases, but it is not suitable for all pregnant women suspected of having abnormal fetuses. It is generally believed that the following types of pregnant women need to undergo amniotic fluid examination: pregnant women who have given birth to anencephaly, spina bifida, or other neural tube defects have a 5% chance of giving birth to a sick baby in their next pregnancy; pregnant women who have given birth to children with congenital metabolic defects have a 25% risk of their offspring suffering from the same disease when they give birth again; pregnant women who have given birth to children with chromosomal abnormalities have a higher risk of giving birth to children with the same disease in their next pregnancy regardless of their age; pregnant women with a family history of recessive genetic diseases can prevent the birth of children with serious recessive genetic diseases by predicting the sex of the fetus;

For older pregnant women over 35 years old, the relative risk of giving birth to children with chromosomal abnormalities, such as congenital idiocy, increases with the increase of the pregnant woman's age; pregnant women with a history of contact with teratogenic factors within three months of pregnancy, these factors include certain drugs, viral infections, radiation, chemicals and pesticides and other harmful and toxic substances; pregnant women who are married to close relatives and pregnant women who the doctor believes need to undergo amniocentesis.