April 13, 2024

What to expect with this pregnancy screening procedure.

Not everyone who is pregnant will need an amniocentesis. However, your care team may recommend one under certain circumstances.

“An amniocentesis is a procedure where you sample the baby’s amniotic fluid,” said Dr. Rolanda Lister, a maternal-fetal medicine specialist with Vanderbilt Women’s Health. “Typically an amniocentesis is done to get genetic information or if there is concern for an infection.”

Your care team wants you to know that an amniocentesis is safe and what to expect if you need to undergo the procedure. Here are answers to questions you might have if you’re considering an amniocentesis.

What happens during an amniocentesis?

During an amniocentesis, your doctor will insert a needle through your abdomen, uterus and amniotic sac, which contains the amniotic fluid. With the needle, your doctor will be able to sample the fluid, which can then be sent off to the lab for various tests.

It can help diagnose various genetic conditions and fetal abnormalities, including Down syndrome, cystic fibrosis, muscular dystrophy, sickle cell disease and more.

Your doctor may recommend an amniocentesis if a previous pregnancy was affected by one of these conditions, if you have a family history of one of these conditions or if a prenatal screening showed a high risk of one of these conditions.

Will it hurt?

The procedure is relatively painless, aside from the needle poke. “It feels kind of like a mosquito bite or getting an IV started,” Lister said. If you are concerned about pain, you can request lidocaine. However, that will involve more needle pokes.

What, if any, are amniocentesis risks?

Your provider will use imaging to guide the needle. “What that means is that we use an ultrasound the entire time so that we can see exactly where the needle is entering into the amniotic sac,” Lister explained.

The ultrasound guidance helps ensure accuracy and safety. However, a small risk exists for pregnancy loss. That risk is less than 1% when you’re in the second trimester of pregnancy.

If a patient has a bloodborne disease, such as HIV or hepatitis C, there may be a risk of disease transmission to the fetus. However, the risk is significantly reduced if the patient is on antiretroviral therapy for HIV or has a low viral load for hepatitis C.

When is the best time to undergo the procedure?

An amniocentesis can be done at any time during a pregnancy. “However, there are times when there is a much lower risk of complications,” Lister said.

Generally, an amniocentesis is best performed after 15 weeks of gestation but before 22 weeks.

Generally, an amniocentesis is best performed after 15 weeks of gestation but before 22 weeks, she added. Before 15 weeks, the chorion and amnion membranes have not yet fused, so an amniocentesis could cause bleeding behind the sac. After 22 weeks, an amniocentesis presents a potential risk of preterm labor.

What happens after?

After an amniocentesis, the risk for complication is low for infection, bleeding or preterm labor, Lister said. Patients should know that having some contractions post-procedure is normal, but contractions should dissipate within a few hours.

“If they are having a lot of contractions, their water breaks or they are bleeding,” Lister added, “those are reasons to go to the hospital to get evaluated.”

Expert care for you and your baby

Each pregnancy and delivery is unique and yours should be too. Learn more about how Vanderbilt Health’s obstetrics and maternal fetal medicine teams bring together nationally ranked expertise and personalized care from your first prenatal visit to delivery and beyond.

To learn more, call 615-343-5700 or schedule an appointment online.

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