Amniocentesis: what is it and how is this diagnostic test performed?

This test is designed to detect genetic diseases before the baby is born.

Pregnancy and gestation are very delicate stages, since in this Biological process the new organism begins to develop. That is why, from a medical point of view, it is important to know as much as possible about what is happening during pregnancy. to know as much as possible about what is happening in the development of the fetus, in order to be able to intervene as soon as possible in the development of the fetus.This is why, from a medical point of view, it is important to know as much as possible about what is happening in the development of the fetus, in order to intervene as soon as possible in case of congenital diseases.

Amniocentesis is the procedure that doctors perform to obtain this early information and to be able to make an early diagnosis during pregnancy. and to be able to make an early diagnosis during pregnancy. Throughout this article we will review everything you need to know about this test: what is amniocentesis, what are its functions, how it is performed and what are the risks to be taken into account.

What is an amniocentesis?

We call amniocentesis a type of prenatal test in which, through a medical procedure, an early diagnosis is made of chromosomal diseases and of chromosomal diseases and fetal infections and, secondarily, it also helps us to know the sex of the baby before birth.

To understand how it works, we must first know that throughout the gestational stage the fetus is surrounded by a substance called amniotic fluidwhose composition is made up of fetal cells. From the observation of this fact, the scientific community applied to the clinical field has discovered that the amniotic fluid is capable of giving us useful information about the baby's health months before birth. Amniocentesis focuses on the analysis of this substance and its components.

When amniocentesis is performed, a small sample of amniotic fluid is obtained through the use of a needle that is introduced into the woman's abdomen at the same time as an ultrasound is performed. a needle that is introduced into the woman's abdomen at the same time as an ultrasound scan is performed to monitor the process. ultrasound, which can be used to monitor the process. Secondly, the sample of amniotic fluid obtained is analyzed in the laboratory, where the DNA of the fetus is studied to see if there are any genetic abnormalities.

In which cases is it performed?

This prenatal test is only offered to women who present a significant risk of genetic disease. In most cases, the main reason for performing an amniocentesis is to find out if the fetus has a chromosomal or genetic abnormality such as Down syndrome. As a general rule, this diagnostic procedure is scheduled between 15 and 18 weeks of gestation..

Thus, it is not always necessary to do it, in most cases it is only performed in those pregnant women in which the baby is at risk of developing a genetic pathology. The reason why it is not done for all women is that it is a fairly invasive test that carries a small risk of invasive test that carries a small risk of miscarriage..

Since amniocentesis is associated with certain risks, a complete anatomical ultrasound is performed before it is performed in order to detect abnormalities in the baby. In cases where there is reason to suspect the existence of genetic or chromosomal alterations, amniocentesis will be performed.amniocentesis will be performed.

Functions of this test: what is it used for?

The main cases in which an amniocentesis is required include:

• A A family history of birth defects.
• Abnormal ultrasound test results.
• Women with pregnancies or children in which there were birth or gestational disorders.

Unfortunately, amniocentesis cannot detect all possible birth defects. However, the ultrasound test performed at the same time can detect birth defects that cannot be reported by amniocentesis, such as cleft lip, heart defects, cleft palate or clubfoot.

However, the risk of some birth defects that are not detected by either diagnostic test cannot be ruled out. In general, the main conditions detected by amniocentesis are are:

• Muscular dystrophy.
• Cystic fibrosis.
• Sickle cell disease..
• Down's syndrome.
• Alterations in the neural tubesuch as occurs in spina bifida.
• Tay-Sachs and related diseases.

Finally, the accuracy of amniocentesis is about 99.4%, so although it has certain dangers, it is very useful in cases where there is a real suspicion of fetal anomaly.

How is it performed by physicians?

After cleaning the area of the abdomen where the needle will be inserted with an antiseptic and administering a local anesthetic to relieve the pain of the puncture, the medical team locates the position of the fetus and the placenta using an ultrasound scan. Guided by these images, a very fine needle is inserted through the mother's abdominal wall, the wall of the uterus and the placenta.The needle is inserted through the mother's abdominal wall, the wall of the uterus and the amniotic sac, trying to keep the tip away from the fetus.

A small amount of fluid is then withdrawn, about 20 ml, and this sample is sent to the laboratory where the analysis will be performed. In this space, the fetal cells are separated from the rest of the elements present in the amniotic fluid.

These cells are cultured, fixed and stained in order to observe them correctly under the microscope. Thus, chromosomes are examined for the chromosomes are examined for abnormalities..

As for the baby and its environment, the puncture seals and the fluid of the amniotic sac regenerate during the following 24-48 hours. The mother should go home and rest for the rest of the day, avoiding physical exercise. Within a day, she can return to normal life unless otherwise instructed by the physician.

The risks

Although medical safety measures have advanced greatly in this area as well, amniocentesis is always a risky procedure, amniocentesis always presents risks.. The risk of miscarriage is the most notorious, although it occurs in only 1% of cases.

The possibility of premature delivery, injuries and malformations in the fetus is also an aspect to be taken into account.

Bibliographic references:

• Carlson, L. M. & Vora, N. L. (2017). Prenatal Diagnosis: Screening and Diagnostic Tools. Obstetrics and Gynecology Clinics of North America, 44(2): 245–256.
• Seeds, J. W. (2004). Diagnostic mid trimester amniocentesis: how safe?. American Journal of Obstetrics and Gynecology, 191(2): 607–15.
• Underwood, M. A, Gilbert, W. M, Sherman, M. P. (2005). "Amniotic Fluid: Not Just Fetal Urine Anymore". Journal of Perinatology. 25 (5): pp. 341 - 348.