What is amniocentesis?
Amniocentesis is one of the two main prenatal diagnostic tests to assess risks, problems, or genetic disorders in the fetus. The other main diagnostic test is Chorionic Villus Sampling (CVS). These tests are both karyotype tests — tests that analyze chromosomes.
Amniocentesis uses an ultrasound transducer to show the baby’s position inside the uterus; the doctor then uses a needle to withdraw a sample of the amniotic fluid surrounding the baby. The doctor extracts fetal cells from this fluid and examines them.
Before your test, Dr. Rad will perform an ultrasound to accurately determine the baby’s gestational age.
Who performs amniocentesis?
Amniocentesis is a specialized procedure performed by a maternal-fetal medicine (MFM) specialist, also known as a perinatologist. These are OB/GYNs who have completed additional fellowship training – typically two to three years beyond residency – specifically focused on high-risk pregnancies and complex prenatal procedures. Not every OB/GYN performs amniocentesis, so it’s important to know you’re in the right hands.
Dr. Steve Rad is a double-board-certified OB/GYN and maternal-fetal medicine specialist with extensive experience performing amniocentesis for patients with high-risk pregnancies throughout the Los Angeles area. His subspecialty training in perinatology means he brings a level of precision and clinical expertise to the procedure that goes well beyond routine obstetric care. Whether you’ve been referred by your OB or are seeking a second opinion, you can feel confident that Dr. Rad has performed this procedure countless times and understands the anxiety that often comes with it.
During the procedure, a maternal-fetal medicine specialist works alongside a sonographer to use real-time ultrasound guidance – this is what makes the procedure safe and accurate. At the Maternal Fetal Care Center, Dr. Rad uses state-of-the-art imaging technology to guide every step with care and precision. We understand that agreeing to amniocentesis can feel like a big decision, and we want you to feel supported from the moment you walk through the door. That is the Dr. Rad difference – expert, concierge-level care with a genuine personal touch every step of the way.
What does amniocentesis test for?
Amniocentesis is a diagnostic tool that can detect a range of fetal conditions, and understanding what it tests for – and who performs amniocentesis – helps expectant parents feel more confident going into the procedure. A qualified Maternal-Fetal Medicine specialist, also known as a perinatologist, should always perform amniocentesis. Dr. Rad’s double-board certification in OB/GYN and Maternal-Fetal Medicine means you are in the most experienced hands possible throughout this process.
The conditions amniocentesis can identify include:
Genetic conditions. The fetus’s chromosomes are examined to check for conditions such as Down Syndrome and other chromosomal abnormalities. Amniocentesis is approximately 99% accurate for chromosomal diagnoses, making it one of the most reliable prenatal tests available.
Fetal lung maturity. When performed later in pregnancy, the test can determine whether the baby’s lungs are sufficiently developed for birth – important information if early delivery is being considered.
Fetal infection. The amniotic fluid can be evaluated for signs of infection or other illnesses affecting the baby.
Neural tube defects. Unlike chorionic villus sampling (CVS), amniocentesis can detect neural tube defects such as spina bifida – an important distinction when Dr. Rad is helping you decide which test is right for your situation.
The timing of the test also shapes what it can detect. When performed between 11 and 14 weeks, it provides early insight into your baby’s genetic makeup. Between 15 and 20 weeks, it is often used alongside other procedures to build a fuller picture of your pregnancy. Dr. Rad will guide you on the right timing based on your individual needs – that personal touch is at the heart of the Dr. Rad difference.
When to perform an amniocentesis?
Broadly, the test is performed on women who may be at risk for birth defects, or as a follow-up to an earlier screening test that signals there may be a problem. Amniocentesis is typically recommended between weeks 15 and 20 of pregnancy, and it is always performed by a highly trained specialist. A maternal-fetal medicine specialist (also called a perinatologist) carries out the procedure – someone with advanced sub-specialty training in high-risk pregnancies beyond standard OB/GYN qualifications. Dr. Steve Rad is double-board certified in OB/GYN and maternal-fetal medicine, meaning patients receive expert, hands-on guidance from consultation through to results.
Potential high-risk pregnancies that may call for amniocentesis include:
Advanced maternal age (35 or older): The risk of chromosomal conditions such as Down syndrome increases with age, making amniocentesis a common recommendation for mothers in this group.
Abnormal prenatal screening results: If an earlier blood test, cell-free DNA (cfDNA) test, or ultrasound exam raises a concern, amniocentesis can provide a definitive diagnosis.
A previous pregnancy affected by a chromosomal condition or genetic disorder: A personal history of carrying a baby with a genetic condition significantly raises the likelihood of recurrence.
A known family history of genetic conditions: If either parent carries a gene mutation – such as those linked to cystic fibrosis or sickle cell disease – amniocentesis can confirm whether the baby has inherited it.
Rh incompatibility: When a mother’s blood type is Rh-negative and the baby’s is Rh-positive, amniocentesis can help monitor the severity of any complications.
Signs of a neural tube defect: Unlike CVS (chorionic villus sampling), amniocentesis can detect neural tube defects such as spina bifida – an important distinction when choosing which diagnostic test is right for you.
Uterine infection concerns: Later in pregnancy, amniocentesis may be used to check for signs of infection in the amniotic fluid.
We understand that being referred for amniocentesis can feel overwhelming. At the Maternal Fetal Care Center, Dr. Rad and his team treat every patient as a VIP – walking you through each step with clarity, compassion, and the personal touch that defines the Dr. Rad difference.
What happens during amniocentesis testing?
Amniocentesis is performed by a maternal-fetal medicine specialist (also called a perinatologist) – a physician with advanced sub-specialty training in high-risk pregnancy care. Dr. Rad is double-board certified in OB/GYN and maternal-fetal medicine, making him uniquely qualified to perform this procedure with precision and care.
The test usually takes place in a doctor’s office, but if we suspect complications, the procedure may take place in a hospital.
An ultrasound first examines the baby’s heart rate and the position of the placenta, fetus, and umbilical cord.
A small amount of numbing medicine is injected into the mother’s abdomen. Once numb, a very thin needle is guided into the uterus and amniotic sac using continuous ultrasound guidance – so we can see exactly what we are doing at every step.
After collecting about an ounce of amniotic fluid, the needle is removed, and the sample is placed in a sterile, light-protected container. We then send it to the lab to measure the baby’s protein levels and screen for chromosomal or genetic conditions. Results typically come back within three to four days for some tests, though certain analyses can take up to two weeks. We will walk you through every finding – whether the results point to something that needs attention or, best of all, give you complete peace of mind.
Call (844) 473-6100 or click here to schedule online
Amniocentesis vs CVS: Is one test better than the other?
The main benefit of CVS is that it can be done earlier in the pregnancy. It’s very accurate at detecting genetic abnormalities, but it doesn’t detect some things that amniocentesis does. These include:
Neural tube defects (involving the spinal column or brain)
Birth defects
Rh incompatibility (when the mother has Rh-negative blood and the baby has Rh-positive blood)
Amniocentesis might be the best option if:
You are past the first trimester, and CVS is no longer an option
Your provider needs to screen for neural tube defects or Rh incompatibility, which CVS cannot detect
A prior screening test – such as an early fetal scan or cell-free DNA test – returned an abnormal result that requires confirmation
You have a family history of a specific chromosomal or genetic condition that requires a more comprehensive analysis of the amniotic fluid
Neither test is universally “better” – the right choice depends entirely on your gestational age, your medical history, and what your provider needs to learn. That conversation is best had with a maternal-fetal medicine specialist, also called a perinatologist, who has the subspecialty training to interpret results and guide your care. Who performs amniocentesis? In most cases, it is a perinatologist – a physician with advanced fellowship training in high-risk pregnancies and prenatal diagnostics. Dr. Rad is double-board certified in OB/GYN and maternal-fetal medicine, which means he not only performs the procedure with precision but can also walk you through exactly what your results mean and what comes next. We understand this can feel like an anxious time, and that personal touch – having one expert guide you from testing through results – is the Dr. Rad difference.
- You previously had a baby with a neural tube defect.
- You or your partner has a neural tube defect.
- Other tests during your pregnancy have shown abnormal results. This could include an early pregnancy blood screening test.
- There are chromosomal abnormalities.
Amniocentesis complications and risks
Though usually uneventful, the risks of amniocentesis are very small. These include:
Amniotic fluid leak. This typically rectifies itself within a week.
Risk of miscarriage. Fewer than .03% of tests performed in the second trimester result in miscarriage. The rate is higher when amniocentesis is performed before the second trimester.
Needle injury. If the baby moves during the test, they may get nicked by the needle. This is very rare.
Rh sensitization. The baby’s blood cells may enter the mother’s bloodstream. An injection of Rh immune globulin corrects this.
Infection. This is quite uncommon, but the test can trigger a uterine infection.
Mild cramping and vaginal bleeding.
Amniocentesis results: what do they mean?
Once your sample is collected, you’re probably going to be anxious about what comes next – and that’s completely understandable. Knowing what to expect from your results can make the waiting period a little easier to navigate.
Turnaround time depends on what’s being tested. Chromosomal abnormalities like Down syndrome (trisomy 21) typically take about 3 to 4 days when a rapid FISH (fluorescence in situ hybridization) test is used. A full chromosomal analysis, which looks at your baby’s complete genetic makeup, usually takes about 1 to 2 weeks. Tests for specific infections or neural tube defects may have their own timelines, so your provider will give you a clearer window based on your individual situation.
As for accuracy, amniocentesis is considered one of the most reliable prenatal diagnostic tests available – with an accuracy rate of approximately 99%. Remember, though, that no test is 100% perfect, and results are always interpreted alongside your full clinical picture.
A negative result means no chromosomal abnormalities or genetic conditions were detected – reassuring news for many families. A positive result means a condition was identified. This doesn’t automatically determine a course of action; rather, it opens a conversation with your care team about next steps, support options, and what the diagnosis means for your pregnancy going forward.
If you have a high-risk pregnancy, having a maternal-fetal medicine specialist like Dr. Rad interpret your results ensures you receive expert guidance – not just numbers on a page, but real answers delivered with compassion and clarity. That is the Dr. Rad difference.
Frequently asked questions about amniocentesis
After learning about the risks and complications of amniocentesis, it’s completely natural to have more questions. Here are answers to some of the most common ones we hear from patients.
Who performs amniocentesis?
A Maternal-Fetal Medicine specialist, also called a perinatologist, performs amniocentesis. This physician has advanced subspecialty training in high-risk pregnancies and complex prenatal procedures. Dr. Steve Rad is double-board certified in OB/GYN and Maternal-Fetal Medicine, meaning you’re in highly experienced hands throughout the entire procedure. Having a specialist of this caliber perform your amniocentesis significantly reduces procedural risk and ensures the most accurate guidance for your results.
Does amniocentesis hurt?
Most patients describe the sensation as pressure or mild discomfort rather than sharp pain. The skin is cleaned, and a thin needle is carefully guided using real-time ultrasound imaging, so the procedure is precise and typically completed within a few minutes. Some cramping afterward is normal, but it usually resolves quickly with rest and acetaminophen if needed.
How accurate is amniocentesis?
Amniocentesis is one of the most reliable prenatal diagnostic tests available, with an accuracy rate of approximately 99% for chromosomal conditions like Down syndrome. It’s considered a diagnostic test rather than a screening test, meaning it provides a definitive answer rather than a probability estimate.
How long does it take to get amniocentesis results?
Results typically come back within 3 to 4 days for rapid FISH testing, or up to 2 weeks for a full chromosomal analysis. If you have a high-risk pregnancy, Dr. Rad will walk you through every result personally, ensuring you never feel alone in the process.
What to expect after amniocentesis
After the procedure, you’ll rest briefly while your care team monitors you and your baby. Most patients can go home within 30 to 60 minutes, but plan to take it easy for the rest of the day. Think of it as a good excuse to put your feet up – because it genuinely is.
Here’s what’s normal in the hours and days that follow:
Mild cramping or pressure at the needle insertion site is common and usually fades quickly.
Light spotting may occur and typically resolves on its own.
Acetaminophen (Tylenol) can help manage any discomfort – avoid ibuprofen or aspirin during pregnancy unless your doctor advises otherwise.
For the first 24 to 48 hours, avoid strenuous activity, heavy lifting, and exercise. Most patients return to their normal routine within a day or two.
It’s also important to know when to call your doctor right away. Contact your maternal-fetal medicine specialist immediately if you experience:
A fever above 100.4°F
Heavy vaginal bleeding
Leaking amniotic fluid
Severe or worsening cramping
Unusual fetal movement changes
Most chromosomal findings come back within 3 to 4 days via rapid testing, while full genetic culture results can take up to two weeks. Dr. Rad and his team will walk you through every result personally – because we understand this can be an anxious time, and you deserve clear answers and compassionate guidance every step of the way. That is the Dr. Rad difference.
Why choose Dr. Steve Rad and the Los Angeles Fetal and Maternal Care Center?
Did you know that all pregnancies in the United States are at risk of becoming high-risk? Even a pregnancy that begins “low-risk” can become high-risk. That is no secret to Dr. Steve Rad, a double-board-certified obstetrician-gynecologist with subspecialty training in Maternal-Fetal Medicine/Perinatology.
Dr. Rad has been named a top doctor and Maternal-Fetal Medicine specialist in Los Angeles by LA Magazine for six years in a row.
Dr. Rad completed rigorous training with high honors at renowned institutions, including the Department of Obstetrics and Gynecology at David Geffen School of Medicine at UCLA, USC, Cedars-Sinai Medical Center, and UCSF Medical Center, as well as centers internationally in London, Austria, Israel, and Africa.
Dr. Rad is passionate about obstetrics and gynecology and uses his proficiency to guide high-risk mothers with prenatal testing, special monitoring, and diligent care during their pregnancy – up to and including delivery.
Dr. Rad and his OB/GYN team understand your information needs before, during, and after birth. We help you understand your pregnancy, answer all your questions, and provide the emotional support and means to safely navigate your pregnancy.
Call us at (844) 473-6100 or schedule your consultation online. We are currently accepting new patients.
We are conveniently located for patients throughout Southern California and the Los Angeles area at locations in or near Beverly Hills, Santa Monica, West Los Angeles, West Hollywood, Culver City, Hollywood, Venice, Marina del Rey, Malibu, Manhattan Beach, Newport Beach, Irvine, and Downtown Los Angeles. We also offer in-home prenatal care and a fly-in program for out-of-town and international patients. Dr. Rad even travels to patients who need him throughout the U.S. and around the world.
If you can’t make it to Dr. Rad, he also offers virtual consultations worldwide.
Call (844) 473-6100 or click here to schedule online
Written by Dr. Rad Education Team
Medically Reviewed by Dr. Steve Rad
