A patient having a scan

We encourage you to bring your partner or relative or friend to support you in labour

Ultrasound scans

An ultrasound scan, sometimes called a sonogram, is a procedure that uses high-frequency sound waves to create an image of part of the inside of the body.

We use ultrasound scans to monitor an unborn baby.

What scans can I have?

If you are pregnant in England, you will be offered two ultrasound scans: one at around 11 to 14 weeks of pregnancy and one at around 20 weeks. If it is deemed medically necessary, you may be offered additional viability scans in early pregnancy or growth scans after 21 weeks.

11 weeks and 2 days to 14 weeks and 1 day scan (Dating Scan)

The dating scan usually takes about 20 minutes.

The purpose of the dating scan is to check:

  • how many weeks pregnant you are and work out your due date (the estimated date of delivery or ‘EDD’)
  • whether you are expecting more than one baby
  • that the baby is growing in the right place
  • your baby's development

This scan may also be part of a combined screening test for Down’s, Edward’s and Patau’s syndromes. The combined test involves a blood test and measuring the fluid at the back of the baby's neck (nuchal translucency) during the scan.

Combined screening for Down's, Edward’s and Patau’s syndrome will happen at the dating scan if:

  • you have agreed to have screening for the conditions
  • the scan takes place between 11 weeks and 2 days and 14 weeks and 1 day of pregnancy when the crown rump length (CRL) measurement of the baby is between 45.0mm and 84.0mm. The CRL is the length of the baby from the top of their head (crown) to the bottom of their buttocks (rump)

You will not be offered the combined screening test if your dating scan happens after the baby’s CRL is more than 84mm, or if the CRL or nuchal translucency cannot be accurately measured.  Instead, you will be offered another blood test (the ‘Quadruple’ test) between 14 weeks and 1 day and 20 weeks of pregnancy to screen for your chance of having a baby with Down's syndrome. This test is not quite as accurate as the combined test and cannot test for Edward’s or Patau’s syndromes. Your sonographer will explain this to you when you come for your scan.

20 week scan (Anomaly scan)

This detailed ultrasound scan is performed on or near 20 weeks of pregnancy and usually takes about 30 minutes. The purpose of the anomaly scan is to check the physical development of your baby, particularly the 11 physical conditions set out by the Fetal Anomaly Screening Programme.  Unfortunately, it is not possible to pick up every condition and there is always a chance that a baby may be born with a health issue that scans could not have identified.

The 20 weeks screening scan is carried out in the same way as the dating scan. It produces 2D black and white images that gives sectional views of the baby. The sex of the baby can usually be identified during this scan.

More information about screening tests for you and your baby is available on the NHS website.

If you have not received an appointment for your dating or anomaly scan one week before the scan is due, please contact the scan department or your community midwife.

Viability scans

If there are medical concerns with your pregnancy you may be offered a viability scan which will check to see the growth, health and wellbeing of your early pregnancy. These are emergency scans which will be as long as is deemed necessary for the medical professionals to assess your pregnancy. They usually last less than 20 minutes.

Growth scans

These are offered to you, after 21 weeks, if you are identified as being on a higher risk pathway. They are primarily to check baby’s growth and wellbeing and are used alongside other tests to make clinical decisions about the best way to manage your pregnancy. A growth scan usually takes around 20 minutes.

What happens at a scan?

Most scans are carried out by specially trained staff called sonographers. In order for the sonographer to get good images of your baby, the scan is carried out in a dimly lit room and you will need to attend with a full bladder for your Dating scan but not for your 20 week scan.

  • You will be asked to lie on a couch.
  • You will be asked to raise your top to your chest and lower your skirt or trousers to your hips.
  • Tissue paper will be tucked around your clothing to protect it from the ultrasound gel, which will then be put on your abdomen.
  • The sonographer passes a hand-held probe over your skin to examine the baby’s body. The gel ensures there is good contact between the probe and your skin.

The scan does not hurt but the sonographer may need to apply slight pressure to get the best views of your baby. This might be uncomfortable. A black and white picture of your baby will then be seen on the ultrasound screen. During the examination sonographers need to keep the screen in a position that gives them a good view of your baby. You may have a monitor to look at or be shown the images at the end of the scan.

The scan is a medical examination. We will ensure you understand what is going to happen. You will be asked to give your permission for it to be carried out. Feel free to ask any questions. The person scanning you may need to concentrate quietly at certain points during the scan but will answer your questions before or after. General mobile phone usage is not permitted in the scanning room.

Sometimes it is difficult to get good views of a baby. This does not mean there is anything to worry about. Very occasionally the scan cannot be completed; this may be because a baby is lying in an awkward position or you are above average weight - which can increase transmission depth. Should it be clinically necessary, you will be offered an additional scan to get better images; however, should a scan be unsuccessful, please be assured your baby will be offered an all-over physical examination after birth.

Who can I bring?

You may like someone to come with you to the scan appointment. It is expected that the mother or birthing person will attend the hospital, for the scan, with one adult only.

Children are not permitted to attend scan appointments as they can often be distracting to the sonographer whilst they are carrying out important clinical checks and also to parents whilst they are absorbing essential information.

A screening environment is not appropriate for children as it can be distressing for them to witness their parents upset if anomalies or pathology relating to the baby are found.

Most hospitals do not allow children to attend scans as childcare is not available. If there are exceptional circumstances and you cannot arrange childcare, please contact your scan department to discuss this with them.

How can I get pictures of my baby?

We ask that photographs or videos are not taken during the scan using mobile phones or other recording equipment. This is for the following reasons:

  • Pathology relating to the baby or birthing woman or person may be revealed during the scan- which can be very distressing. It is not appropriate to record or photograph such events.
  • Sonographers require high levels of concentration during obstetric ultrasound examinations. Video recording and additional lighting from phones can be distracting and distort a Sonographer’s vision. Birthing women or persons and their attendee should refrain from general mobile phone usage during the scan for the same reason.
  • Privacy of staff should be respected and they should be able to fulfil their job without being recorded.

Parents are given the opportunity to buy an ultrasound image. It costs £5 for one image or £10 for three images. This charge is to cover the cost of the thermal paper used. Images may be requested at any scan but the length of the scan must not be extended in order to obtain a ‘good’ picture.

Please note that thermal images should not be subjected to heat (e.g. laminating) and the long term stability of thermal images is not known.

Can I know my baby’s sex?

If requested by the birthing woman or person, sonographers are able to provide an opinion on the sex of the baby at the anomaly scan. This will depend on the position of the baby and other factors, so cannot always be seen.

It is not a requirement of the NHS Fetal Anomaly Screening Programme so no additional time is provided to look for the sex of the baby. It is important that sonographers spend as much time as they need to check the structures of the baby and perform the diagnostic scan without delays to scan lists. They are unable to spend longer looking for the sex of the baby or to book another scan if they cannot offer an opinion at the time of the scan.

If the sonographer can see, they will tell you their opinion on sex at the time of the scan. This opinion is not 100% accurate.

As this is an NHS funded scan for clinical reasons sonographers will not provide an opinion on fetal sex to any other persons not in attendance nor in an envelope for ‘gender reveal’ purposes. Alternative providers outside the NHS may be able to offer this service- please ensure that they employ qualified sonographers.

Zero Tolerance to abuse in the NHS

We have a zero tolerance policy towards violence, aggression or harassment of any sort of our staff, this includes social media abuse.  All incidents will be logged with our trust safety and security management, and the appropriate partnership teams notified. Patient records will be marked with relevant information.

Complaints, compliments and feedback

Please contact the Patient Advice and Liaison Service or share your experience with the Maternity Voices Partnership who work closely with the local trusts to represent your views and improve standards.


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