What aspects of the fetus does amniocentesis primarily examine?

Generally, amniocentesis primarily examines fetal chromosome abnormalities, fetal genetic diseases, fetal infection status, fetal lung maturity, and fetal neural tube defects. Details are as follows:

1. Fetal Chromosomal Abnormalities: Amniocentesis can detect whether the fetus has chromosomal abnormalities such as Down syndrome, Edwards syndrome (trisomy 18), and Patau syndrome (trisomy 13). By collecting amniotic fluid samples and analyzing the fetal cells within, the number and structure of chromosomes can be assessed for normalcy.

2. Fetal Genetic Diseases: Amniocentesis can diagnose certain genetic diseases, such as cystic fibrosis, sickle cell anemia, thalassemia, phenylketonuria, hemophilia, and albinism. These diseases are typically caused by gene mutations. By testing for gene mutations in the amniotic fluid, it can be determined whether the fetus carries a specific genetic disease.

3. Fetal Infection Status: Amniocentesis can detect whether the fetus has been infected intrauterinely, such as by cytomegalovirus or toxoplasmosis. By testing for pathogens in the amniotic fluid or the fetus's immune response, potential infection risks can be assessed and appropriate treatment measures taken.

4. Fetal Lung Maturity: Amniocentesis can assess the maturity of the fetus's lungs, particularly when there is a high risk of preterm birth. By analyzing phospholipid components in the amniotic fluid, such as the ratio of lecithin to sphingomyelin, the developmental maturity of the fetus's lungs can be determined. A lecithin/sphingomyelin ratio greater than or equal to 2 indicates mature fetal lung function, whereas a ratio less than 1.5 indicates immature lungs.

5. Fetal Neural Tube Defects: Amniocentesis can assist in diagnosing fetal neural tube defects such as anencephaly and spina bifida. By measuring alpha-fetoprotein levels in the amniotic fluid, the risk of open neural tube defects in the fetus can be assessed.

It should be noted that amniocentesis is an invasive diagnostic procedure that carries certain risks, such as failure of amniotic fluid cell culture, miscarriage, bleeding, or leakage of amniotic fluid. Therefore, prior to deciding whether to undergo amniocentesis, it is recommended to fully understand relevant information and make informed decisions under the guidance of a physician. Additionally, pregnant women should choose reputable hospitals and have the procedure performed by qualified physicians to minimize risks.