Fetal anatomy scan

All pregnant women should be offered an anatomy exam as part of standard antenatal care.

This normally happens at 18 to 22 weeks. It is also called an 'anomaly scan'.

Fetal anatomy scans can tell you:

  • how your baby is developing
  • if your baby has birth defects like spina bifida and heart problems
  • the sex of your baby - scans can sometimes get this wrong, or it may not be possible to tell depending on how your baby is lying in the womb

Most scans will show you that your baby is developing normally.

Scan results

Sometimes babies can have health problems while they are developing in your womb. A fetal anatomy scan will detect many of these problems.

This allows you and your midwife or obstetrician to make plans for the birth and for any aftercare you and your baby may need.

If they identify a problem, you will be offered an appointment with a fetal medicine specialist.

We will keep you and your partner or support person fully informed throughout this process.

The scan will not detect all health issues. No test is 100% accurate. Some health issues do not show up on the fetal anatomy scan.

These include:

  • some cases of Down syndrome
  • some cases of cerebral palsy
  • autism

If the scan shows that your baby is growing too quickly or too slowly, extra scans may be offered to check your baby's growth.

Sometimes extra tests like amniocentesis or CVS sampling might be recommended to confirm a diagnosis.

Baby's sex

Sometimes the radiographer or midwife doing the scan may not be able to see parts of your baby’s body. For example, they may not be able to see the genitals to determine your baby's sex.

If you do not wish to know the sex of your baby during the scan, tell the person doing the scan.

Bring someone with you

An ultrasound scan can be a happy event. But sometimes they can detect that your baby is unwell. Or you might get unexpected news, such as you're expecting more than 1 baby.

If you are allowed to bring a support person, having someone with you will be a good support at this time.

Maternity hospital service disruptions

Page last reviewed: 10 February 2023
Next review due: 10 February 2026

This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.