What is amniocentesis for examination
Release time : 07/26/2025 09:30:01
For pregnant mothers, the most joyful thing is to be able to see the baby in their belly. To ensure timely monitoring of the baby's condition, it is necessary to regularly undergo check-ups.
Amniocentesis is a test included in prenatal screenings. So, what does amniocentesis actually check? When should amniocentesis be performed? What is the principle behind amniocentesis? What exactly does amniocentesis assess for? Before undergoing an amniocentesis, many people are unaware of what the test actually measures. 1. It can diagnose chromosome abnormalities, genetic disorders, and metabolic diseases, identifying congenital deafness, cerebral palsy in children, etc., for subsequent fertility interventions; 2. It can diagnose fetal neural tube defects such as anencephaly or spina bifida; 3. It can examine fetal lungs, kidneys, liver, and skin maturity; 4. It can predict the fetal blood type and diagnose neonatal hemolysis.
5. Detection of intrauterine infection, such as increased amniotic fluid volume, may indicate subclinical intrauterine infection; 6. Aid in the diagnosis of premature rupture of membranes (PROM), since the pH value of amniotic fluid should be greater than 7 due to its alkaline nature.
The optimal time for amniocentesis is not always available, and the doctor will advise you on the best timing for the procedure. So, when is the optimal time for amniocentesis? The amniocentesis procedure is often performed around 15-16 weeks of pregnancy.
However, not all pregnant women need to undergo this test.
Doctors usually recommend amniocentesis for elderly pregnant women and pregnant women at risk of treatment.
Amniocentesis is a simple instrument that extracts amniotic fluid from pregnancy and extracts a few milliliters of sterility to determine the health of the fetus.
This kind of operation is best performed during pregnancy. It is difficult to extract specimens from one week's premature amniotic fluid and can easily damage the fetus; the fetus has developed into abnormalities in the late stage and is not suitable for continued pregnancy.
Abortion of pregnancy program will make the operation difficult and increase the risk of mother harm.
The optimal time for amniocentesis during prenatal diagnosis is approximately week 1 of pregnancy, as the fetal eggs are relatively abundant and there is a relatively wide amniotic fluid band around the fetus drifting in the amniotic fluid. With this configuration, it is easier to perform the needle puncture without harming the fetus; only 1 mL of sample needs to be collected.
The total volume of amniotic fluid does not cause a sudden reduction in the size of the uterine cavity, nor can it lead to miscarriage. During this period, the proportion of living cells in the amniotic fluid is the highest, and cell-rich cultures can be used for prenatal chromosome analysis, genetic diagnosis of chromosomes, sex determination, and genetic DNA testing for metabolic disorders. Amniotic fluid can also diagnose fetal neural tube defects.
The principle behind amniocentesis is that it allows a medical practitioner to examine the condition of the fetus within the womb through certain techniques. However, many individuals are unaware of the exact mechanism behind this procedure. The technique involves extracting amniotic fluid from the fetus's skin, gastrointestinal tract, and urinary tract, among other areas, and uses free cells to further analyze whether the fetal chromosomes are abnormal.
The extraction of amniotic fluid is primarily used to analyze the fetal chromosome composition, with Down syndrome being the most common and significant condition.
Some monogenic diseases such as B-thalassemia and hemophilia can be diagnosed through the examination of genes (DNA composition) in amniotic fluid cells.
Additionally, the fetus exhibits several major defects such as spinal encephaloceles, hydrocephalus of the meninges, umbilical hernia, and abdominal wall defects. Furthermore, AFP in amniotic fluid can be examined to obtain a more accurate reference value.
Amniotic fluid can also provide some biochemical substances to understand the fetal lung maturity.
Under the guidance of an ultrasound probe, a fine needle is introduced through the abdominal wall to penetrate the myometrium and amniotic cavity. 20-30 ml of amniotic fluid is aspirated for examination of chromosomes, DNA, and fetal cell biochemical constituents.
Currently, the most commonly used prenatal diagnostic techniques are.
The operation is simple and requires no anesthesia or hospitalization before puncture.
Application of amniocentesis Many pregnant mothers are very familiar with the technology of amniocentesis, but most people don't know much about the application of this technology. So what are the applications of amniocentesis? 1. Understand whether the fetus has abnormal chromosomes. Amniotic fluid cell culture chromosome karyotype analysis can detect fetal chromosome abnormalities, including abnormal number or structure of abnormal chromosomes, and abnormal number or structure of sex chromosomes.
2. Upon centrifugation of amniotic fluid cells stained with chromosomal preparations, the sedimented specimen is directly dropped.
Regular processing and staining with X and Y chromosomes in amniotic fluid interphase cells are used for therapeutic purposes of inheritance diseases.
3. Congenital metabolic disorders can be identified through the determination of various enzymes in amniotic fluid cell cultures, which can confirm the presence of metabolic diseases in fetuses.
4. Prenatal diagnostics for genetic diseases, directly use DNA extracted from amniotic fluid cells and detect using labeled specific probes.
A test gene has been found to be missing, partially missing or mutated.
Amniocentesis is not necessarily recommended to be done more frequently; there are inherent risks associated with it, so it's important for pregnant mothers to understand the level of risk involved when assessing their baby's condition.
Amniocentesis has been used for 30 years in prenatal diagnosis.
It has been recognized by the medical community, whether for accuracy or safety.
Difficulty of amniocentesis varies from person to person, mainly related to the position of the placenta, fetal position, volume of amniotic fluid at the site of aspiration and fetal movement.
Approximately 2% - 3% of pregnant women experience mild uterine contractions and vaginal bleeding after a needle procedure, which usually subsides with rest or fetal treatment.
Only about 0.5% of pregnant women have metritis, premature rupture and miscarriage.
Since the procedure is currently performed under ultrasound guidance, there may be minimal harm to the fetus.
Furthermore, amniocentesis is employed for prenatal diagnosis of fetuses between 16 and 22 weeks of gestation. At this stage, the fetus has completed its body formation, including the limbs, so it does not cause fetal malformation.
There may be vaginal blood, amniotic fluid overflow or continuous contraction of the uterus, which occurs in about 2% of pregnant women.
Special treatment is usually not required and has no adverse effect on the pregnancy process.
Spontaneous abortions related to amniocentesis account for approximately 0.3% to 0.5%.
The medical part covered in this article is for reading and reference only.
In the event of discomfort, it is recommended to seek medical attention immediately. The diagnosis and treatment should be based on an in-person medical consultation.