Written by

Roxanne Albert, BSN, RNC-OB

December 1, 2025

What to Expect at Your Second Trimester Anatomy Ultrasound

Medical, Pregnancy

If you’re heading into your second trimester and preparing for your anatomy ultrasound, you might be feeling a mix of excitement and anxiety. You’re not alone—this appointment is one of the most anticipated (and nerve-wracking) milestones of pregnancy. It’s an incredible moment to see your baby up close, but it’s also the time when providers evaluate important developmental details, which can understandably bring up some nerves.

This blog breaks down exactly what happens during the anatomy scan, what your provider is looking for, why follow-up scans are sometimes needed, and why the vast majority of parents leave with reassuring results.

Subscribe to our YouTube Channel for more weekly workouts and educational videos! We publish one new workout video and 2-3 educational videos a week on our channel.

What Is the Anatomy Scan — and When Does It Happen?

The anatomy ultrasound is typically performed between 18 and 22 weeks of pregnancy, with the ideal timing falling as close to 20 or 21 weeks as possible. At this size, baby is developed enough for clearer visualization, but still small enough for a full scan.

Scheduling too early (before 19–20 weeks) often leads to repeat scans simply because baby was too small or positioned in a way that made certain structures hard to see. So if you haven’t scheduled yet, aiming for that 20-week mark increases the chances of getting everything assessed in one visit.

Why This Appointment Feels So Big

As a mom who’s had four anatomy scans, I know this appointment brings a lot of anticipatory anxiety. This is the moment your provider gets a detailed look at:

Baby’s organs
Baby’s limbs and skeletal structure
Placenta and umbilical cord
Amniotic fluid levels
Uterus and cervix

If something is structurally off, this is the scan where it’s most likely to be identified.

But here’s the very reassuring part: True abnormalities show up in only 2–3% of scans. That means 97–98% of anatomy ultrasounds come back completely normal.

Most re-scans are simply because the sonographer couldn’t get a clear enough picture—not because something is wrong.

A Head-to-Toe Look at Baby

During the anatomy scan, the sonographer evaluates every major part of your growing baby:

Skeletal Structure

Skull bones
Facial bones
Nose and palate
Spine
Arm and leg bones
Hands, fingers, feet, and toes

Brain Development

They look at whether baby’s brain is forming normally and if all major structures are in place.

Organ Development

Including:

Heart — all chambers, valves, and blood flow patterns
Kidneys
Liver
Stomach and bladder
Diaphragm

The heart and spine are the two most common structures they have difficulty seeing clearly—so don’t be surprised if you’re asked to come back for a second look.

Measuring Baby’s Growth

The anatomy scan is also a mini growth scan. Key measurements include:

Head circumference
Abdominal circumference
Femur length

These give an estimate of baby’s size and whether growth aligns with your due date. A single growth scan can be off slightly, so try not to stress if baby measures a little ahead or behind—your provider will let you know if there’s anything to monitor.

Placenta Position & Health

Your provider also checks:

Where the placenta is located:

Anterior (front of uterus)
Posterior (back)
Fundal (top)

Or it might be low-lying or covering the cervix—called placenta previa.

If the placenta is too close to the cervix, you’ll be re-scanned later. The good news?
Up to 90% of low-lying placentas move upward as the uterus grows.

Placental shape and attachment

They assess whether:

There are extra lobes
The umbilical cord inserts centrally, off-center, or at the edge
There’s a velamentous cord insertion (a variation that sometimes needs extra monitoring)

Umbilical Cord Assessment

A normal umbilical cord has three vessels:
👉 two arteries and one vein.

Ultrasound can confirm this using blood flow imaging.
If only one artery is present (a single umbilical artery), your provider may recommend more frequent growth monitoring.

Cervical Length & Amniotic Fluid Levels

Your cervix should typically measure 3–5 cm during the mid-pregnancy scan. If it’s shorter, your provider may talk to you about next steps.

Amniotic fluid is measured either by:

The largest visible pocket, or
The four-quadrant method, adding up pockets from four areas of your abdomen

Normal amniotic fluid levels fall between 5 and 24.

Finding Out Baby’s Sex

If you didn’t do first-trimester genetic screening, the anatomy scan is often when parents find out the sex of their baby. Baby’s position plays a big role, but most of the time the sonographer can determine it.

Screening for Soft Markers or Congenital Differences

The sonographer and provider will look for:

Structural differences
Soft markers that may indicate a chromosomal condition

Soft markers don’t mean that something is wrong—they simply cue providers to see whether further genetic counseling or testing would be helpful.

If anything looks unclear or unusual, your provider may refer you to:

Maternal Fetal Medicine (MFM)
A genetic counselor

These specialists help explain findings in detail and discuss what they may mean for your pregnancy.

What Happens After the Scan

Once the sonographer finishes, they send all images to your OB or midwife to review. They will then go over:

What looked normal
What couldn’t be seen clearly
Whether any follow-up scans are recommended
Whether referral to an MFM specialist is advised

Common reasons for follow-up scans:

Baby’s position blocked full visualization
Heart or spine needed a clearer look
Placenta was low or cord insertion unclear
Fluid measurements were borderline
Growth needed re-checking
Soft markers were seen and need monitoring

None of these automatically mean something is wrong—they often just mean your provider wants more information.

The Bottom Line: Most Anatomy Scans Are Reassuring

While the anatomy scan can feel intense, remember:

✔ 97% of scans show no concerning findings
✔ Most re-scans are due to positioning—not abnormalities
✔ You get an incredible look at your baby
✔ This scan helps personalize your care and keep your pregnancy safe

And of course, many parents walk away with adorable ultrasound photos, and sometimes even 3D or 4D images.

Share Your Experience & Find More Pregnancy Support

If you’ve already had your anatomy scan, share your experience—good, challenging, surprising, or reassuring. Your story might help calm someone else’s nerves.

For more support during pregnancy or postpartum, explore MamasteFit’s childbirth education, prenatal fitness programs, and postpartum recovery resources! Be sure to use code YOUTUBE10 for 10% off.

If you have topics you’d love to see covered next, drop them in the comments—we’re always here to help support your journey.