17.02.2025
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5 min reading Amniocentesis: indications, timing
Amniocentesis is a method of prenatal (prenatal) diagnosis that allows you to detect complex diseases, including hereditary ones, in the unborn child with a high probability. There are many scary rumors surrounding this analysis, but we will not panic, but we will figure out which of them are true and which are not.
- What is amniocentesis?
- Why is this procedure needed?
- When is amniocentesis indicated?
- Deadlines
- Contraindication
- Preparing for amniocentesis
- How is the procedure?
- Well-being monitoring
- We are waiting for the results.
What is amniocentesis?
The baby grows and develops in the amniotic sac filled with amniotic fluid for 9 months before birth. It contains nutrients and waste products of the fetus. When a possible pathology that threatens the life of the child cannot be detected on ultrasound or with the help of other tests, the pregnant woman is prescribed amniocentesis. This medical term is formed from two words: “amnion” - fetal membrane and “kentesis” - puncture (translated from Greek).
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Why is this procedure needed?
As the name suggests, amniocentesis is an invasive procedure (one that penetrates the skin or mucous membranes of the body). Most often, its essence is to access the amniotic fluid through a puncture, obtain amniotic fluid, and analyze it for possible fetal pathology.
In addition, amniocentesis is used:
- in case of polyhydramnios - to pump out excess amniotic fluid (so-called amnioreduction);
- for injecting medication into the amniotic cavity if necessary;
- for the administration of special drugs for artificial termination of pregnancy in the second trimester for medical indications;
- for the collection of amniotic fluid as a component of serum from the embryonic tissues of the fetus from 16 to 21 weeks (fetotherapy) - it is used to treat many diseases;
- in fetosurgery - surgical treatment of the fetus.
Source: Fotolia
The amniocentesis procedure is prescribed in cases where there is a possibility that the fetus has serious problems that threaten its health and life, and ultrasound or other tests do not give a clear answer as to whether this is true or not.
Amniocentesis is done to detect:
- hereditary diseases;
- chromosomal pathologies, primarily Down syndrome (there are about 200 pathologies in total);
- genetically determined metabolic disorders (over 60 varieties);
- degree of maturity of fetal tissues;
- the presence of intrauterine infections;
- malformations of the nervous tissue.
When is amniocentesis indicated?
Amniocentesis is a complex procedure, and of course, no one will force you to do it. However, there are a number of very clear indications when it is not just recommended, but necessary. These are:
- incompatibility of the blood of the fetus and mother;
- chronic intrauterine oxygen starvation (hypoxia) of the fetus;
- the need to determine the sex of the child as accurately as possible before birth;
- suspicion of congenital, hereditary diseases, intrauterine infections;
- the pregnant woman is over 35 years old;
- positive alpha-fetoprotein test results, indicating possible fetal neural tube defects;
- previous pregnancies ended in the birth of children with pathology.
Source: Fotolia
It is definitely worth undergoing the amniocentesis procedure if family members have been diagnosed with:
- Down syndrome;
- hemophilia;
- Duchenne syndrome;
- Edwards syndrome;
- Turner and Klinefelter syndrome;
- thalassemia;
- phenylketonuria and other severe hereditary diseases.
Deadlines
The optimal period for using amniocentesis is considered to be 16-18 weeks of pregnancy. However, in cases where the doctor suspects a heart defect in the fetus or the presence of serious genetic diseases, the procedure can be performed earlier - up to 14 weeks. It is possible to use the amniocentesis method at later dates, after 18 weeks - for the purpose of artificial termination of pregnancy for medical reasons.
Source: Fotolia
Contraindication
There are few of them. Amniocentesis is not prescribed in the following cases:
- placental abruption, abnormal location of the placenta;
- exacerbation of chronic diseases;
- acute urogenital infections;
- uterine pathologies;
- threat of premature abortion;
- tumor-like neoplasms in the muscle layers of the uterus;
- the presence of postoperative scars;
- blood clotting disorders in the mother.
Acute respiratory diseases also fall into this list - it is better to wait until you are fully recovered and only then go for the procedure.
In case of hepatitis C and B, HIV infection, and other infectious diseases of the mother, the analysis can be done: the risk of infecting the child is minimal.
In case of categorical contraindications to amniocentesis, the doctor may offer you an alternative - chorionic biopsy or cordocentesis.
Preparing for amniocentesis
Everything is simple here. A pregnant woman needs to take the necessary tests and undergo an ultrasound scan, stop taking acetylsalicylic acid and all drugs containing it a week before the procedure, and stop taking anticoagulants a day before amniocentesis. In addition, the parents sign a consent to this procedure.
Source: Fotolia
How is the procedure?
Puncture of the amniotic sac is performed through the anterior abdominal wall. This is done under constant ultrasound monitoring to ensure that the needle does not damage the placenta and fetus. Sometimes, extremely rarely, a puncture is performed through the anterior vaginal fornix.
In general, the procedure is painless. To carry it out, it is enough to treat the injection site with an antiseptic and apply local anesthesia. Occasionally, women note unpleasant sensations during the puncture - burning, contraction of the uterine muscles. The procedure takes a few minutes, the volume of amniotic fluid obtained is 3-30 ml.
After the procedure, the doctor will assess the condition of the pregnant woman and the fetus, and if necessary, administer medications, for example, to prevent bleeding. The procedure does not require hospitalization, so you can go home immediately after the puncture.
Well-being monitoring
The test went well and you went home. Most often, amniocentesis is without complications, but you should consult a doctor in the following cases:
- pulling pains in the lower abdomen appeared and they intensified;
- the puncture site turned red and festered;
- body temperature has increased;
- bloody discharge appeared;
- if amniotic fluid leaks from the wound even a day after amniocentesis.
Source: Fotolia
It cannot be ignored that in rare cases, but still, the consequences of amniocentesis can be negative:
- development of infection - 1 in 200 cases;
- bleeding in the woman or fetus;
- miscarriage — approximately 1 in 500 cases, or premature birth;
- Although the risk of injury tends to zero, such a probability still exists;
- damage to the amniotic sac.
If the mother is Rh negative, she is given an injection of Rho-gamma globulin before the test to protect the fetus from her antibodies. In about 2 out of 100 cases, this can cause a miscarriage.
We are waiting for the results.
Some of the results will be known in 2 days, but you will receive a complete answer to all questions in about 2-3 weeks, since the research process requires growing cells obtained from amniotic fluid on a nutrient medium. And this takes time. The probability of the results is about 99,5%, so doctors prescribe it to be sure of their suspicions or their groundlessness. There is no point in describing the answer forms in case of fetal pathology - they are individual for each person. But if your baby is genetically healthy, on the form you will read - 46ХХ (boy) or 46ХХ (girl). But if Down syndrome is confirmed, the number will be 47 - an extra chromosome will be added to the total number.
Based on the results of the analysis, doctors decide whether to continue the pregnancy. But even if a woman has decided for herself that she will give birth anyway, knowing the situation will allow her to prepare for the arrival of a special child in the family.
The editorial opinion may not coincide with the opinion of the author of the article.
Use of photos: Clause 4, Article 21 of the Law of Ukraine "On Copyright and Related Rights" - "Reproduction for the purpose of covering current events by means of photography or cinematography, public communication or communication of works seen or heard during such events, to the extent justified by the informational purpose."
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