Amniocentesis is a highly accurate prenatal test that can be used to diagnose congenital health conditions or genetic disorders in the foetus before it is born. This can be helpful in making a decision about continuing the pregnancy or considering termination and preparing for the arrival of a child with special needs.
It can provide useful information about the developing foetus’s health, but one must consider the risks of the procedure and the possible outcomes of the test.
What is an Amniocentesis Test?
An amniocentesis pregnancy test is a type of prenatal test that is usually performed during the second or third trimester of pregnancy. It is done to diagnose genetic disorders and other health conditions in the developing foetus. A biopsy is performed with the help of a long, thin needle and an ultrasound scan to take a sample of the amniotic fluid from inside the uterus and test it in a lab for specific conditions.
The amniotic fluid contains cells from the foetus that carry genetic information about the baby and help in diagnosing genetic conditions. It is important for individuals to discuss the procedure in detail, why they need to take the test, possible outcomes, and other doubts.
When is amniocentesis recommended?
All pregnant women are not advised to undergo amniocentesis. It is recommended for women who have a higher likelihood of their foetus having a genetic condition due to their family history and other factors. Generally, this test is recommended when the test results might affect the management of a pregnancy. Amniocentesis is usually performed between the 15th and 20th weeks of pregnancy.
Amniocentesis is offered to pregnant women under the following circumstances:
- A screening test indicated the possibility of the foetus having congenital conditions such as Edward’s syndrome, Down’s syndrome, and Patau’s syndrome
- A previous pregnancy was affected by a genetic condition
- A genetic condition in the family history, such as thalassemia, sickle cell disease, muscular dystrophy, or cystic fibrosis
Why is Amniocentesis Performed?
Amniocentesis can be performed for different reasons, including the following:
Genetic testing
Also known as genetic amniocentesis, this involves taking a sample of the amniotic fluid and testing the DNA from the cells to diagnose genetic conditions. This is often recommended after a screening test suggests a genetic condition affecting the foetus.
Diagnosing foetal infection
In some cases, amniocentesis may be used to look for infections or other illnesses in the baby when it is still developing.
Treatment
Amniocentesis can be used to drain excess amniotic fluid from the uterus if it could affect the baby’s growth. This occurs due to a condition called polyhydramnios.
Foetal lung testing
If the doctor plans the delivery of the baby before 39 weeks for some reason, they may suggest amniocentesis to check whether the baby’s lungs have sufficiently matured for birth or not. However, this is very rare.
Amniocentesis can also detect congenital disabilities like Tay-Sachs disease, spina bifida, anencephaly, and Rh disease.
Amniocentesis Test: Procedure
The procedure starts with the patient changing into hospital gown or comfortable clothes to allow the doctor access for an ultrasound scan and the collection of the amniotic fluid sample. Then the doctor applies a special gel to assist with the ultrasound, which helps in getting clear visuals of the patient’s internal organs by using high-frequency sound waves.
The ultrasound scan enables the doctor to check the position of the baby, find an appropriate site to remove amniotic fluid, and perform the procedure safely without harming the foetus. The ultrasound is performed during the procedure to guide the needle, and the visuals can be seen on a monitor.
Before inserting the needle, the doctor may administer anaesthesia to numb the abdomen and make the procedure more comfortable for the patient. The injection usually doesn’t sting a lot, and most people don’t need anaesthesia.
The doctor will clean the abdomen with an antiseptic liquid to minimise the risk of infections. Then, they will insert a long, thin needle through the abdominal wall into the uterus using the ongoing ultrasound scan. The needle penetrates the amniotic sac to collect fluid for testing later on. The doctor ensures that the baby is not harmed during this procedure. They take out a small sample of the amniotic fluid for testing. In a few cases, the doctor needs to take the sample again if they could not collect adequate fluid on the first attempt. The patient may be asked to get the test done at a later time if the second attempt is also unsuccessful. The doctor will conclude the procedure by giving the patient a tissue to wipe the gel off of their abdomen.
Amniocentesis is usually not a painful procedure, but it can be uncomfortable. Some women also experience a pain similar to period pain or pressure when the needle is taken out. The discomfort lasts for a few hours at most.
The whole procedure takes about 10 minutes to perform and about 30 minutes in total, including the consultation and ultrasound. The patient will be monitored for an hour or so for observation if the procedure causes any side effects, such as heavy bleeding. The patient can usually go home and rest. It is best to have company to get home safely.
Preparing for the Test
Generally, one doesn’t need to prepare for amniocentesis and can eat or drink as usual. In some cases, the doctor may advise avoiding urinating for a few hours before the test, as a full bladder can help with the test results. People can bring loved ones to accompany them during the test for support.
Interpreting Test Results
The amniocentesis test is about 99% accurate (1) in detecting abnormalities in the foetus, but it cannot detect the severity of the condition. Additionally, in some cases, the lab professionals may not be able to analyse the amniotic fluid as expected due to certain factors, such as not collecting sufficient sample; however, this is uncommon.
The test results can be delivered to the patient within 3–4 days or may arrive up to two weeks later (sometimes longer). This depends on the type of test that the lab technicians need to perform. After getting the test results, the doctor may provide genetic counselling to the patient to help them understand the results of their pregnancy and the available options for them moving forward if amniocentesis shows that the foetus has a specific health condition. A neonatologist can suggest a specific care plan, including surgeries or medication, for the baby. Additionally, if the patient decides to keep the baby, the doctors will guide them about the type of care the child might need during different stages of their life.
Risks Associated with the Amniocentesis Test
Amniocentesis can be considered an invasive procedure for the developing foetus. The risks of amniocentesis occur very rarely, and they include the following:
Amniotic fluid leaks
There are chances that the amniotic fluid can leak through the vagina after amniocentesis. Generally, the amount of fluid loss is not significant and stops within a week or so, with no effect on the pregnancy.
Miscarriage
If women undergo amniocentesis during their second trimester of the pregnancy, there is a minimum chance of miscarriage; if the procedure is carried out before 15 weeks, the chances of miscarriage increase dramatically.
Rhesus disease
If the mother has a RhD negative blood type and the baby has a RhD positive blood type, it is possible that the baby can have rhesus disease. To prevent this, the doctors will conduct a blood test to assess the risk.
Club foot (or talipes)
Having amniocentesis before 15 weeks of pregnancy may cause the foetus to develop a deformed ankle and foot.
Infection transmission
If a woman has infections such as hepatitis C, HIV/AIDS, or toxoplasmosis, there is a risk of transmission of these infections to the baby during the amniocentesis procedure.
Alternatives to Amniocentesis
Chorionic villus sampling (CVS) is often recommended as an alternative to amniocentesis. CVS is performed usually between the 11th and 14th weeks of a pregnancy. The procedure involves testing the placenta for any abnormalities, but it cannot detect neural tube defects. The CVS test can give parents more time to decide on how to proceed with their pregnancy in case of abnormal results.
Although there are other tests that are used to check for different health conditions in the developing foetus, amniocentesis is considered the gold standard by healthcare professionals to check for congenital health conditions.
Cost of Amniocentesis
The charges for an amniocentesis test depend on various factors, including the location and the type of lab equipment used. On average, amniocentesis test prices can range from INR 7,000 to INR 18,0000 in India.(2)
The Bottom Line
Amniocentesis is an important (optional) test that can help detect a genetic condition in the foetus during the early stages of pregnancy. This can help the parents make an informed decision about their baby’s future. The parents are informed about the associated risks and given the choice to get the test done. The amniocentesis test can help you in the following ways:
- Determine the best treatment for the baby if they have a health condition
- Start planning for a child with special needs
- Make arrangements to support your baby
- Identify resources for the baby
One can always choose not to go through the amniocentesis pregnancy test and take the associated risks. Some people don’t go through the test if their decision about the pregnancy does not vary on the basis of the test results or if they don’t wish to take the risk of harming the foetus during the procedure.
The amniocentesis test may be emotionally challenging for some people and create stress. It is important to seek support from our loved ones or seek professional help if necessary.
