Amniocentesis: what is it, when is it performed and other options

• Amniocentesis has some risks, including the risk of the amniotic sac rupturing and foetal loss (risk of 0.8% - 1%).
• Non-invasive prenatal testing is used to detect trisomies 21, 18 and 13, foetal sex determination and sex aneuploidy.
• Free foetal DNA analysis is the most effective test to determine the risk of the most common chromosomal disorders in pregnancy and does not carry any risk for the mother or the foetus.

During pregnancy there are many prenatal tests that you will have to undergo to ensure that everything is progressing correctly, that your baby's development is normal and under control, and that your health is not in any danger.

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Each trimester of pregnancy involves a series of follow-up medical examinations. These tests are carried out, in the case of the mother, to find out fundamental aspects of her health that may affect the baby, such as:

• Blood group
• Diabetes of pregnancy or gestational diabetes
• Anaemia
• Immunity to certain diseases
• Sexually transmitted diseases
• Cervical cancer

For the baby, prenatal tests can identify:

• Treatable health problems during gestation
• Characteristics of the baby: sex, size, position, age,...
• Possible birth defects, genetic problems or other conditions

Among the obligatory prenatal examinations we can distinguish the following:

• Ultrasound scans: during each trimester you will have an ultrasound scan to check the baby's growth and position inside the uterus.
• Blood tests: to determine the possibility of risk of suffering from any disease or syndrome, as well as to detect gestational diabetes or anaemia.
• Vaginal and rectal cultures to rule out streptococcus agalactiae.
• Foetal monitors: you will lie down and have a device attached to your belly that records your baby's heartbeat and the contractions of your uterus.

As you should already know, if, as the trimesters go by, the tests show that everything is going well, both in terms of your baby's development and your state of health, you will not need any further prenatal tests. 

However, in the event that during the consecutive medical examinations, abnormalities are detected in the pregnancy or a risk to the development of your child is determined, the professionals will resort to more complex tests.

These tests are performed if an abnormality is increasingly suspected, moving on to more invasive techniques such as amniocentesis or chorionic villus sampling. Such diagnostic tests examine placental tissue and amniotic fluid to see if your baby has a genetic condition, such as Down's syndrome, or another type of birth defect.

Please note that before resorting to an invasive test, you should consult your specialist about alternative tests, such as non-invasive prenatal tests, which can be performed to confirm the need for amniocentesis or chorionic villus sampling.

Here are all the details about amniocentesis and other non-invasive prenatal screening tests, which can confirm or deny the need for invasive risk testing.

The amniotic fluid in which the foetus floats during pregnancy contains a large number of foetal cells, as the baby sheds its excretions in this fluid: those shed from its skin, intestine and kidney cells.

Amniocentesis is one of the most commonly used tests to analyse all these cells floating in the amniotic fluid to determine whether the foetus has any chromosomal irregularities.

What does this prenatal diagnostic test consist of?

Amniocentesis consists of the extraction of amniotic fluid by means of a puncture with a very fine, long needle through the abdominal wall of the mother's womb, passing through the uterine wall and the placenta to reach the amniotic fluid.

The procedure is monitored by ultrasound. This provides visual control of the path of the needle inside the mother's body, the position of the amniotic sac and the position of the foetus at any given moment during the test.

During this procedure, the doctor extracts 20 to 25 millilitres of amniotic fluid. The amount depends on the stage of gestation you are at, from which the chromosomes are extracted and analysed, and the process lasts between 20-30 minutes.

After the amniocentesis, you will need to rest at home for the next 48-72 hours. It is recommended that you do not do any sporting activities or have sexual relations during these days of recovery after the test.

When is an amniocentesis performed?

Amniocentesis is performed between 15 and 20 weeks of pregnancy. Performing it before the 15th week of gestation is associated with a higher rate of complications.

This test is often performed for a variety of reasons and medical recommendations, such as:

1. Maternal age >35 years. In mothers over 35 years of age, there is an increased risk of the baby having a chromosomal disease, such as Down's syndrome.
2. Previous pregnancies with chromosomal conditions or neural tube defects. If you have had a previous pregnancy affected by a chromosomal disease or a serious condition that affects the baby's brain or spinal cord. One of the most recommended tests is amniocentesis.
3. Family history of a specific genetic disease, as well as in case the mother and/or father are conscious carriers of a genetic disease.
4. Abnormal ultrasound findings. If abnormalities or defects in the baby's growth are observed, specialists recommend an amniocentesis to detect and diagnose the possible disease.
5. Positive results of non-invasive prenatal screening tests. Amniocentesis is recommended in case of positive or worrisome first trimester screening results or foetal free DNA testing to confirm or rule out a diagnosis.

Do you want to find out if you need an amniocentesis or not? Buy your non-invasive prenatal test voucher and find out the risk values associated with the health of your unborn baby, receiving the results in just 10 days after the analysis.

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What is this test for?

Some prenatal tests are screening tests and only reveal the possibility of a problem. Other prenatal tests are diagnostic techniques, which means that they can determine, with a good degree of accuracy, whether the foetus has a specific problem. Therefore, a screening test is most often followed by a diagnostic test.

Babies with trisomy 13 or 18 do not usually survive after birth, but those with Down's syndrome do.

In the case of amniocentesis, we are talking about a diagnostic test. The purpose of this test is to detect and confirm chromosomal alterations, in which the foetal cells present in the amniotic fluid are studied and results are obtained that reveal whether your child has a chromosomal condition or birth defect before birth.

Amniocentesis detects any chromosomal alteration, as the baby's entire karyotype is studied. The most frequent are:

• Trisomy of chromosome pair: 21 (Down's syndrome), 13 (Patau's syndrome) and 18 (Edwards' syndrome).
• Alterations in the sex pair on the X and Y chromosomes (Aneuploidy).
• Genetic diseases of genetic inheritance from father and/or mother carriers.
• Genetic conditions caused by non-inherited mutations.
• Degree of pulmonary maturity of the foetus.
• Spina bifida.
• Existence of infection.

Amniocentesis results

The definitive results of the amniocentesis usually take 3 to 4 weeks. Your gynaecologist will be in charge of explaining all the details about the information and diagnosis obtained from the test.

If at first, a more generic screening is done, approximate, partial results can be obtained, known as FISH (fluorescence in situ hybridisation) or QF-PCR, also called "rapid tests”. These results are obtained in less time and detect some trisomies. For the full karyotype, the final result has to be awaited.

Amniocentesis is a very safe test and the results are known to be 100% reliable. However, the risks of this test should be seriously considered before undergoing the test and the possible results should be assessed.

We explain the characteristic risks of amniocentesis below.

During amniocentesis, you will usually experience mild pain at the time of the puncture, as well as discomfort in the abdominal area as the needle passes through the uterus.

Once the procedure is completed, you may experience side effects with amniocentesis, such as:

• Risk of stillbirth after the test. Placental abruption, significant loss of amniotic fluid, uterine contractions or infection can cause premature delivery. The risk of a baby dying after the test is 1%. After chorionic villus sampling (the risk is 2%), there is no medical test with such a high risk.
• Abdominal pain and/or irritation around the puncture.
• Needle injury. If the baby moves during the test, the needle may stick to the spleen or leg. The severity of the consequences will depend on where the needle is stuck and to what degree. However, this type of injury is very rare.
• Congenital deformity of the baby at birth. Amniocentesis risks damaging a part of the placenta called the amnion, leading to the development of amniotic bridles. These are fluid-filled sac-like cords that surround the baby, preventing normal growth and development, and can cause defects in the baby's face, arms, legs, fingers or toes.
• Bleeding or leakage of amniotic fluid. After the puncture, amniotic fluid may leak through the vagina. Generally, the amount of fluid lost is very small and usually resolves in a maximum of 7 days, continuing with a completely normal pregnancy.
• Rh sensitisation. Amniocentesis may cause the baby's blood cells to enter the mother's bloodstream. Rh disease is a rare condition in which a mother's immune system produces antibodies against a specific protein on the surface of the baby's blood cells.

If you have Rh-negative blood and have not developed antibodies to Rh-positive blood, after amniocentesis you will be injected with a blood product called Rh immune globulin. This will prevent your body from producing Rh antibodies that can enter the placenta and damage your baby's red blood cells.

• Urinary tract infection. After amniocentesis, the risk of urinary tract infection is very low. However, it is important to be vigilant after the test and follow the specialist's instructions to avoid complications.
• Transmission of infections from mother to foetus. During invasive procedures, such as amniocentesis, there is a risk of transmission of pathologies such as HIV, hepatitis C or toxoplasmosis. For this reason, amniocentesis is contraindicated in cases of chronic maternal infections.

You should be clear before you undergo the test whether you are willing to terminate the pregnancy if the diagnosis is positive. It makes no sense to undergo an amniocentesis if you are against termination of pregnancy, thus avoiding any risk or complication. 

Therefore, one of the options provided by professionals, before performing an amniocentesis, is the practice of a non-invasive test, a prenatal screening test for free foetal DNA. 

Non-invasive prenatal tests are screening tests. These tests help to find out if your baby is at high risk of having a genetic condition that affects his or her health.

In addition, this type of analysis can confirm the need for an invasive diagnostic test to determine the genetic disease or birth defect that specifically affects your child.

These prenatal tests pose no risk to you or your baby, as they only require a small sample of maternal blood, just like a routine blood test.

Non-invasive tests include the following:

Harmony Basic Prenatal Test

The Harmony Basic Non-Invasive Prenatal Test is indicated for pregnant women at least 10 weeks gestation, with a single or twin pregnancy, including pregnancies through egg donation (IVF).

This test evaluates the risk of trisomy 21, 18 and 13, i.e. Down's syndrome, Edwards' syndrome and Patau's syndrome, and anomalies in the X and Y chromosomes (Aneuploidies), as well as being able to determine foetal sex.

You will receive the complete results within 5-7 working days. Furthermore, it is not necessary to carry out the test on an empty stomach.

The results of screening tests can help you decide whether you want to have a diagnostic test.

Harmony Medium Prenatal Test

The Harmony Medium non-invasive prenatal test is a prenatal screening, which allows to know the health of the baby with only 10 weeks of pregnancy.

This test is indicated for mothers with a high risk of aneuploidy, whether due to a suspected aneuploidy in the ultrasound, a previous history of trisomy or another risk factor.

This test assesses the risk of trisomy 21, 18 and 13, i.e. Down's syndrome, Edwards' syndrome and Patau's syndrome, and abnormalities in the X and Y chromosomes (Aneuploidy), as well as being able to determine foetal sex (except in multiple pregnancies of only males).

Harmony Extended Prenatal Test

The non-invasive Harmony Extended Prenatal Test is a prenatal screening test, which will allow you to know the health of your baby at only 10 weeks of pregnancy.

This test evaluates the risk of trisomy 21, 18 and 13, anomalies in the X and Y chromosomes (Aneuploidies), and detects the probability of the 22q11.2 deletion known as DiGeorge syndrome. It is also able to determine foetal sex.

In the case of pregnancies with two foetuses or twins, only chromosomes 21, 18 and 13 will be analysed, i.e. sex aneuploidies will not be detected, nor will the 22q11.2 deletion be detected, and the foetal sex will be reported, as long as one of the babies is a boy, or both babies are girls.

If you are interested in having any of these non-invasive prenatal tests, to be sure of the real need to resort to an invasive technique, such as amniocentesis. Or simply, to continue with a totally calm and safe pregnancy.

You can buy your non-invasive prenatal test voucher immediately and very easily by filling in our contact form, calling at +34 91 141 33 56 or clicking on the image below:

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