posted 2nd November 2026
What Happens During a 20-Week Pregnancy Scan?
The 20-week pregnancy scan is a major milestone for many expectant parents.
By this stage, your baby has developed considerably since the early weeks, and the NHS anomaly scan gives trained professionals an opportunity to examine the baby's anatomy in detail.
You may be excited to see your baby again, but it's also natural to have questions about what happens during the appointment, what the sonographer looks for and what the results might mean.
Here's a guide to the NHS 20-week scan and how it differs from a private, non-diagnostic ultrasound.
When does the 20-week scan take place?
In England, the NHS usually offers the anomaly scan between 18 and 21 weeks of pregnancy.
Although it is often called the 20-week scan, your appointment may take place a little earlier or later within this window.
If you have not yet received an appointment or are unsure when it should happen, contact your midwife or maternity service.
The anomaly scan is an important part of routine maternity care and should not be replaced by a private scan.
Why is the anomaly scan offered?
The purpose of the NHS anomaly scan is to examine the baby's development and check for a range of physical conditions.
The sonographer will look at specific structures and measurements according to the screening programme.
The examination commonly includes assessment of the:
- Brain and head
- Face and profile
- Spine
- Heart structures
- Abdomen and abdominal wall
- Kidneys and bladder
- Arms, legs, hands and feet
The scan also includes checks such as the position of the placenta.
The scan can identify some physical conditions, but it cannot detect every condition or guarantee that a baby has no health problems.
Your maternity team can explain the screening process and discuss any findings that need further investigation.
What happens during the appointment?
You will usually be asked to lie on an examination couch while the sonographer applies ultrasound gel to your abdomen.
A handheld ultrasound probe is moved over your skin to produce images of your baby on a screen.
The sonographer will take measurements and examine the required structures. This can take some time because the baby needs to be in a suitable position for different views.
If your baby is facing away or moving into a position that makes certain views difficult, you may be asked to change position or take a short walk.
Occasionally, it may not be possible to obtain every required view during the first appointment, and a further appointment may be arranged.
Can you see your baby clearly?
At around 20 weeks, your baby is much more developed than during an early pregnancy scan.
You may be able to see the head, face, arms, legs and movements on the screen.
However, the anomaly scan is primarily a clinical examination rather than a keepsake photography session. The sonographer's priority is obtaining the views needed for the assessment.
The quality of the images depends on factors including the baby's position and movement, your body tissues and the equipment being used.
Can you find out your baby's sex?
Sometimes, it may be possible to identify the baby's sex during the anomaly scan, depending on the baby's position and the local NHS service's policy.
However, this is not the primary purpose of the appointment, and identification may not always be possible or certain.
If finding out your baby's sex is important to you, ask your maternity service about its policy before the appointment.
A private gender scan is a separate service, but it also cannot guarantee that a clear view will be possible.
What if the sonographer identifies something unexpected?
Most parents attend the anomaly scan hoping to see their baby and receive reassuring news.
If a possible concern is identified, or the sonographer cannot obtain the required views, the maternity team will explain the next steps.
This may involve another scan, a specialist assessment or further investigations, depending on the circumstances.
Being asked to return for another appointment does not automatically mean something is wrong. Sometimes the baby simply needs to be in a different position to obtain the necessary images.
If you have questions about the results, ask your maternity team to explain them and what they mean for your pregnancy.
Is a private scan the same as the 20-week scan?
No. This is an important distinction.
The NHS anomaly scan is a clinical screening examination that checks for a range of physical conditions. It forms part of your maternity care.
At Daisyscan, our private scans are non-diagnostic. They provide an additional opportunity to see your baby and enjoy the ultrasound experience, but they do not replace the anomaly scan or any other medical examination recommended by your healthcare team.
Even if you have booked a private scan around 20 weeks, you should still attend your NHS appointment.
If you have symptoms or concerns about your pregnancy, contact your maternity team rather than relying on a private scan.
How can you prepare for your appointment?
For your NHS anomaly scan:
- Follow the instructions provided by your hospital.
- Arrive at the time stated in your appointment letter.
- Ask your maternity team if you have questions about the examination.
- Be prepared for the appointment to take longer if your baby is not in a suitable position.
- Remember that the scan's primary purpose is clinical screening.
You may also wish to discuss with your maternity team whether you can bring a partner or support person.
Enjoy your pregnancy milestones with Daisyscan
The weeks around the halfway point of pregnancy can be a special time. Your baby is growing, their movements may be becoming more familiar and each appointment brings a new stage in your journey.
If you would like an additional opportunity to see your baby, Daisyscan offers private ultrasound scans in a comfortable and welcoming environment.
Our qualified midwife sonographers provide a supportive experience and explain what can be seen during your appointment.
Your NHS anomaly scan remains an essential part of your maternity care. A private scan can complement your experience, but it cannot replace clinical screening or medical advice.
Suggested further reading from the Daisyscan Blog...
From 16 to 20 Weeks: How Your Baby Changes