An amniocentesis test helps assess fetal health and detects any potential problems in a high-risk pregnancy. In addition, it offers high accuracy of up to 99% compared to the other invasive prenatal tests (1). If you come under the high-risk category, your doctor may suggest this diagnostic test. Keep reading as we bring you the information you need to know about the amniocentesis test in this post.
What Is Amniocentesis?
Amniocentesis is a prenatal diagnostic test to check the amniotic fluid that surrounds the fetus in the uterus. This fluid contains cells and substances that indicate the status of the baby’s health. For this test, the doctor inserts a long, thin needle (of gauge size 0.9mm) into the uterus to collect a small amount of amniotic fluid. Usually, the procedure is done under ultrasound guidance. The fluid is then tested for specific genetic disorders such as Down syndrome, spina bifida, and cystic fibrosis (2). The test results help determine whether or not to continue the pregnancy or deliver early to prevent further complications. This is done at a specific time during pregnancy.
When Is Amniocentesis Done?
Amniocentesis is usually done between the weeks 15 and 20, which is during your second trimester. Some doctors may recommend the test as early as 11 weeks. Amniocentesis done before 14 weeks has higher complication rates (fetal loss, fetal talipes and respiratory morbidity) and it should be avoided before ten weeks. In some cases, an amniocentesis is done even during the third trimester (3). Amniocentesis has many uses, besides understanding the baby’s health status.
Why Do You Need Amniocentesis?
You may require amniocentesis for the below reasons.
The results from prenatal screening tests are abnormal
You had a child with a birth defect or any abnormality
You are 35 years or above, so to rule out the possibility of your baby having chromosomal abnormalities such as Down syndrome
You or your partner is a carrier of genetic disorder such as cystic fibrosis
Your doctor suspects any infection or anemia in the fetus
There is too much amniotic fluid, a condition known as polyhydramnios where amniocentesis is done to relieve pressure effect due to excessive fluid.
Now, let’s understand the process of amniocentesis.
What Happens During Amniocentesis Procedure?
Amniocentesis is an outpatient procedure, meaning you do not have to stay in the hospital. The pain and cramps should not worry you as you can overcome them with a proper rest schedule as advised by your doctor.
How Long To Rest After The Amniocentesis?
You can go back home and rest for about two hours. You may resume your routine after 72 hours. Your doctor gives you detailed instructions on what to do after an amniocentesis (5). Amniocentesis recovery speeds up when limiting specific activities, such as:
lifting above 15 pounds for at least a day
strenuous work or exercises for 72 hours
Traveling in air for 72 hours
Sex for 72 hours
Contact your practitioner if you experience any of the following signs of infection after amniocentesis:
Fever
Severe uterine cramps that last for more than a few hours
Vaginal fluid leakage or bleeding
Unusual or lack of fetal movement
Inflammation or redness at the area of insertion (6)
The test results could take a few days to come in. Depending on the results, your doctor would advise you on a few things.
What Do The Amniocentesis Test Results Mean?
Some results would take a few days while some take up to four weeks. Your healthcare practitioner or a genetic counselor will explain the findings.
Normal amniotic fluid is clear with a light yellow hue. It will not contain any harmful bacteria, and the cells are tested for problems.
The fetal cells are examined carefully and checked for chromosomal number and arrangement that show genetic disorders. There should be 46 chromosomes in 23 pairs. Any defect in them would lead to genetic abnormalities.
In the case of genetic amniocentesis, test results will help diagnose or rule out various genetic disorders, neural tube defects, and chromosomal abnormalities. The probability of detecting the problems is high, but it does not measure the severity of the birth defects.
In the case of fetal lung maturity amniocentesis, normal results assure your baby will survive and is, therefore, ready for birth.
Abnormal results in any of the above cases mean your baby has a chromosomal condition or genetic disorder. However, a few things may affect the results of the test.
What Factors Affect Amniocentesis Test Results?
The amnio results will not be helpful for some reasons, such as:
Fetal blood in the amniotic fluid will falsely increase the Alpha-fetoprotein (AFP) and Acetylcholinesterase (AChE) substance levels that test for neural tube defects (7).
Amniotic fluid, when exposed to light, can falsely show lower bilirubin levels.
Blood or meconium in the amniotic fluid leads to a false result on the maturity levels of the baby’s lungs.
If none of the factors has influenced the test, and the result has indicated a problem, then you need to decide on the future course of action.
What Happens If Your Baby Is Found To Have A Problem?
In such cases, you undergo genetic counseling sessions that provide you with more information. Based on the information, some women opt to continue the pregnancy while some decide to terminate it. Whatever you decide, you will require further support or counseling. Some may find help from support groups while a few require individual counseling.
What Are The Reasons To Take And Not To Take The Amniocentesis Test?
Your reasons for taking up the test or not may vary. Undergoing the test and confirming the diagnosis will provide you with the following benefits:
Opt for a medical intervention (if it exists) to correct the abnormality
Start planning your life to have a child with special needs
Get ready to make lifestyle changes after the child is born
Get in touch with support groups and resources to help deal with your unique situation
Some may not prefer to take up the test for the following reasons:
You are perfectly okay whether or not your baby has a chromosomal defect
You decide against amniocentesis because of the possible harm it may have on the baby
Your personal, religious, or moral beliefs prevent you from terminating your pregnancy or seeking medical intervention
If you decide to go ahead with the procedure, you must be aware of the possible complications it could have.
What Are The Complications Associated With Amniocentesis?
It is a tough decision for any woman to opt for amniocentesis. You need to weigh the pros and cons of the procedure before you decide. As you already know the benefits of amniocentesis, let us take a look at the risks involved in the procedure (8). Note that genetic amniocentesis is done only if the test results will have a significant impact on managing the pregnancy. However, the decision is up to you.
Are There Ways To Reduce Amniocentesis Risks?
Speak to your OB/GYN to recommend a specialist, who has good experience in performing the amniocentesis.
Don’t hesitate to check on the success rate of the professional who is performing it.
Make sure the doctor uses a qualified and registered medical sonographer during the procedure. The sonographer provides constant ultrasound guidance, and this increases the likelihood of the doctor drawing sufficient amount of fluid in the first attempt and that too without harming the fetus.
Below, we have answered a few common questions that you may still have on the procedure.
The CVS is accurate in detecting genetic abnormalities but does not recognize neural tube defects, birth defects, and Rh incompatibility, which amniocentesis does. The CVS can give you results in your first trimester itself whereas amnio cannot give until the second trimester. However, the risks of the CVS are slightly higher than amniocentesis (10).
