Amniocentesis (or “amnio”) is a test that can be done to diagnose genetic conditions or chromosomal abnormalities in the baby. To do this, a sample of fluid in the amniotic sac must be collected via a surgical needle. It can be an intimidating procedure to undergo given its invasive nature and its association with increased risk of miscarriage. This procedure has been around since the 1950s, and since then, many improvements have been made in how it is done and what information can be gleaned.
Nonetheless, it can still carry some risks and not every woman necessarily needs or wants to have one done. This post will cover:
- What is an amniocentesis?
- What can I expect during the test?
- Does this procedure pose any risks to you or your baby?
- What are some reasons for choosing not to get this procedure?
What is an amniocentesis?
This procedure involves taking a sample of amniotic fluid and testing it for the presence of genetic abnormalities. It isn’t necessary for every pregnancy, but if blood tests and ultrasounds screening for abnormalities raise a red flag about a potential birth defect, an amniocentesis can more definitively diagnose neural tube defects or genetic conditions like trisomy 21 (Down’s syndrome), Turner syndrome (only one sex chromosome in the fetus), trisomy 18, and trisomy 13.
Typically, an amniocentesis is performed early in the second trimester. However, if need be, it can be done later in the pregnancy to assess fetal lung maturity or infection.
It’s also important to know that an amniocentesis cannot provide information about structural birth defects, like heart malformations or cleft lip.
What can I expect during the test?
To properly locate where to draw amniotic fluid, your doctor will use an ultrasound to help guide where the needle should go. Then, the doctor will collect a sample of amniotic fluid (about two tablespoons worth of liquid). While the draw itself takes about five minutes, you can expect the entire procedure to take about 45 minutes.
The sample of amniotic fluid will then be sent to a laboratory for processing, and results can take days or weeks to process.
Does this procedure pose any risks to you or your baby?
Many women are understandably concerned about the potential risk for miscarriage associated with amniocentesis. And, while it’s true that increased miscarriage risk was once a significant concern, advancements in the technology for performing this procedure have significantly reduced this risk.
Currently, the risk of miscarriage for amniocentesis is about 1 in 400 pregnancies, with the risk occurring due to infection or premature labor induction. However, as with of all causes of miscarriage, it’s really challenging to connect miscarriage with one specific event, like getting an amnio done. Also, with the use of guided ultrasound imaging, there is little risk of injury to the developing baby.
Signs of complications that warrant immediate medical attention are watery or foul odor in pregnancy discharge, contractions, severe pain, and signs of infection like fever and flu-like symptoms. Some light spotting after an amnio can be expected, but continuous severe bleeding is also a sign to immediately see a medical professional.
What are some reasons for choosing not to get this procedure?
An amniocentesis can be really informative because it can help you plan for what to do if the fetus requires additional surgery (like fetal surgery for spina bifida) and help you address additional resources you might need for the baby.
However, some women choose not to get the procedure because they will carry the baby to term regardless of the results of the amniocentesis. Depending on your own personal preferences and moral philosophies, you may not elect to have an amniocentesis. But if you’re concerned about the medical safety of the procedure, talk to your doctor about your concerns and whether this procedure is right for you.