What Is Amniocentesis and Why Is It Done?

Being offered a test in pregnancy can feel very different from being offered one at any other time. There's more at stake in your mind, the leaflets suddenly seem full of unfamiliar words, and "we'd like to check something" can sit heavily until someone walks you through it properly. Amniocentesis is one of those tests — often mentioned, not always well explained. The short video at the top of this page, under two minutes long, shows the procedure itself and how a sample of amniotic fluid is taken during pregnancy, so it can be a reassuring first look before you read on.

The reason it might come up in conversation

Amniotic fluid surrounds your baby, and it contains some of the baby's cells. By taking a small sample of that fluid and studying the cells in a laboratory, clinicians can look for certain chromosomal and genetic conditions before birth. A test might be discussed after a screening result, because of something seen on a scan, or because of family history — there are several routes to the same conversation, and none of them automatically means something is wrong. It's also worth knowing this is a diagnostic test, not a screening test: rather than estimating a chance, it examines cells directly. If the background to scans is still fuzzy, our guide to ultrasound in pregnancy covers what those routine images can and can't show.

Walking through the appointment itself

You won't be going in blind — quite the opposite. The procedure is done with ultrasound running throughout, so the person performing it can watch the baby, the fluid, and the needle's path on screen at the same time. This ultrasound-guided amniocentesis video shows that view clearly: a steady scan image guiding a fine needle through the wall of the abdomen and into the fluid, where a small amount is drawn off into a syringe. The sample part itself is usually brief. People often describe a pushing or cramping sensation rather than sharp pain, though experiences vary, and the team will talk you through each stage as it happens rather than springing anything on you.

Once you are home, and the waiting begins

Afterwards you're typically advised to take things a little easier for the rest of the day, and mild cramping or discomfort is commonly mentioned in aftercare advice. The fluid sample goes to the laboratory, where the cells are grown and examined — and that growing takes time, which is why results are not instant. For many people, honestly, the waiting is the hardest part of the whole process, harder than the appointment itself. It helps to ask, before you leave, how and roughly when results will reach you, so the wait has a shape to it. Your own team will also tell you which symptoms should prompt you to contact them sooner — that guidance is specific to you, so follow theirs over anything general you read, including here.

A decision that is allowed to take a moment

Amniocentesis is an offer, not an obligation. Your clinicians should explain what the test could tell you, what it couldn't, and — in balanced terms — the risks involved, including the small risk to the pregnancy that is associated with the procedure. There's no single right answer that fits everyone: what matters is what you would do with the information, and how you feel about the balance involved. Take the leaflet home. Talk it over. Ask the question that occurs to you in the car park, not just the ones you remembered in the room. A good team will expect exactly that.

MedicalVideos.com has published trusted medical videos since 2007. The site was founded by Dr. Mohamed Ibrahim, MD, PhD — physician-scientist.

Frequently Asked Questions

Is amniocentesis the same as a screening test?
No. Screening tests in pregnancy estimate the chance of a condition. Amniocentesis is diagnostic — it collects the baby's cells from the amniotic fluid so they can be examined directly in a laboratory.

Does the needle touch the baby?
The procedure is guided by continuous ultrasound, so the person performing it watches the baby and the needle's path on screen throughout and chooses a path through a pocket of fluid. The ultrasound-guided video linked in this article shows how that monitoring works.

How long does the appointment take?
The sampling itself is usually brief, but the appointment around it — discussion, scanning, positioning, and aftercare advice — takes longer. Your clinic can give you a realistic estimate when you book.

When will I get the results?
Not straight away. The cells in the sample need time to be prepared and examined in the laboratory, so there is a wait. Ask your team before you leave how results will be shared with you and roughly when to expect them.

Educational only — this article is general information about amniocentesis, not medical advice and not a recommendation for or against the test. Whether it is right for you depends on your own pregnancy and history; please discuss the benefits, limits, and risks with your own clinician or midwife.