The Benefits and Risks of Chorionic Villus Sampling and Amniocentesis in Prenatal Testing

Pregnancy comes with a lot of decisions — prenatal testing is often one of the first and the most important. While many screening tests can estimate the likelihood of certain genetic conditions, you may want more definitive answers about your baby’s health before birth.

That’s where chorionic villus sampling (CVS) and amniocentesis come in.

These diagnostic tests provide valuable information about your baby’s chromosomes and genetic health, but they also involve important considerations. Our team of experts at Desert Perinatal Associates is here to help you understand the benefits and risks of each procedure so you can make an informed decision about whether they’re right for your pregnancy.

What are CVS and amniocentesis?

Both CVS and amniocentesis are prenatal diagnostic tests that analyze fetal genetic material.  The primary difference is when they’re performed and how the sample is collected.

We typically perform chorionic villus sampling between 10 and 13 weeks of pregnancy. During the procedure, we collect a small sample of placental tissue, called chorionic villi, which contains the same genetic information as the developing baby.

Amniocentesis usually comes later, most often between 15 and 20 weeks of pregnancy. During this procedure, we remove and analyze a small amount of amniotic fluid surrounding the baby.

Because both tests directly examine fetal cells, they can provide more definitive information than screening tests alone.

When are these tests recommended?

Not every pregnancy requires CVS or amniocentesis. Some of our patients carry certain risk factors that warrant this additional testing; others simply want as much information as possible about their baby.

We typically recommend them if:

• A prenatal screening test shows an increased risk for a genetic condition
• An ultrasound reveals findings that warrant further evaluation
• You’ll be 35 or older at delivery
• You have a personal or family history of certain genetic disorders
• A previous pregnancy was affected by a chromosomal abnormality
• You want the most accurate prenatal genetic information available

The decision is highly personal and depends on your individual circumstances, medical history, and preferences.

What are the benefits of CVS and amniocentesis?

One of the biggest advantages of both procedures is accuracy. Unlike screening tests, which only estimate risk, CVS and amniocentesis can usually provide a more definitive diagnosis for many chromosomal conditions, including Down syndrome and other genetic abnormalities.

This information can help families:

• Better understand their baby’s health
• Plan for specialized care if needed
• Coordinate delivery and neonatal care
• Prepare emotionally and practically for the future
• Make informed decisions about pregnancy management

Having clear answers provides reassurance and reduces uncertainty during your pregnancy.

Advantages of CVS

The primary advantage of CVS is timing. Because it’s performed earlier in pregnancy than amniocentesis, you receive answers several weeks sooner.

For parents facing difficult decisions or seeking early information, this timing can be especially valuable.

Early diagnosis also allows additional time for consultations with maternal-fetal medicine specialists, genetic counselors, pediatric specialists, and other members of your healthcare team if needed.

Advantages of amniocentesis

In addition to evaluating chromosomes and many genetic conditions, amniotic fluid can sometimes provide information about other aspects of fetal health, depending on the clinical situation.

Amniocentesis has also been around for decades and remains one of the most widely used diagnostic procedures in prenatal medicine.

Are there any risks?

While both procedures are generally considered safe when performed by experienced specialists, they are invasive procedures and do carry some risks.

Potential risks may include:

• Cramping
• Spotting or light bleeding
• Leakage of fluid
• Infection
• Pregnancy loss

Fortunately, serious complications are uncommon.

Advances in ultrasound guidance and procedural techniques have significantly improved safety over the years. We discuss the specific risks based on your pregnancy and medical history.

Which test is right for you?

There isn’t a one-size-fits-all answer. You may prioritize obtaining information as early as possible and prefer CVS, or you could choose amniocentesis based on timing, test availability, or specific clinical considerations.

The best decision is the one that aligns with your medical needs, values, and goals for your pregnancy.

A consultation with one of our perinatal medicine specialists or genetic counselors can help you understand your options and feel confident about your next steps.

If you’re ready to talk with an expert about weighing your prenatal testing options, contact our friendly staff to request an appointment. We proudly serve families in the greater Las Vegas area.