What to Expect at Your 20-Week Anomaly Scan Appointment

When the scan happens and why it's offered

The mid-pregnancy scan, often called the 20-week scan or anomaly scan, usually takes place somewhere between 18 and 21 weeks of pregnancy. It sits alongside your other antenatal appointments as part of the standard NHS care offered to everyone who is pregnant, and it's one of the two ultrasound scans you'd typically be offered during a first pregnancy.

The main purpose of this scan is to check how your baby is developing at this stage. It's a routine part of the antenatal schedule rather than something extra, but like any screening offered in pregnancy, going ahead with it is entirely your choice. Some people want every scan on offer, others prefer to have fewer, and both are reasonable positions to take.

Getting ready: practical things to sort beforehand

Most of the preparation for this appointment is logistical rather than medical. It can help to think about timing, who's coming with you, and what you want to ask, rather than worrying about what the scan itself involves.

• Check your appointment letter or app for the exact time, location and any instructions about arriving early
• Allow extra time for parking or public transport, especially at busy hospital sites
• Wear something comfortable that allows easy access to your tummy, such as a two-piece outfit
• Bring your maternity notes, whether that's a book, folder or the app your midwife set you up with
• If you have a job, you're entitled to paid time off for antenatal appointments, so let your employer know in good time
• Write down any questions on your phone or on paper so you don't forget them once you're in the room

Who can come along with you

Many people like to bring a partner, close friend or family member to this appointment, and most maternity units are happy for someone to join you if that's what you'd prefer. It's worth checking your specific hospital or clinic's guidance beforehand, as arrangements can vary slightly between areas.

If you'd rather attend alone, or if your support person can't make it on the day, that's completely fine too. The appointment will still go ahead in the same way, and your midwife or the sonographer carrying out the scan will talk you through what's happening as you go.

What the appointment itself tends to involve

On arrival, you'll usually check in at reception and then wait to be called through to a scan room. The appointment itself typically takes longer than earlier scans, simply because there's more to look at as your baby has grown. A sonographer will use ultrasound to look at your baby's development, and you'll usually be able to see the screen alongside them.

It's completely normal for the sonographer to go quiet or move the probe around for a while as they work through what they need to check. This is routine and doesn't necessarily mean anything is wrong. If anything needs further discussion, the sonographer or a midwife will talk you through next steps calmly and clearly, and arrange any follow-up that's needed.

Your choice, your questions

Whether to have this scan, and what to do with any information it gives you, is a personal decision. National guidance on antenatal care is clear that your individual needs and preferences should shape the care you're offered, not the other way round. If you're unsure whether this scan is right for you, or you have questions about what a particular finding might mean for your own pregnancy, your midwife, GP or local maternity service is the right place to ask, rather than trying to work it out from general information alone.

It can help to jot down questions before the appointment so you don't forget them in the moment. Things like how long the scan usually takes at your hospital, what happens if they need a second look at something, or how and when you'll get results, are all reasonable things to ask in advance.

After the appointment and where to find more support

Once the scan is finished, you'll usually be given some initial feedback there and then, and any further appointments or referrals will be arranged through your midwife as normal. Your maternity notes will be updated, so it's worth keeping them with you afterwards in case you need care elsewhere.

If you'd like more general reading on what to expect across the rest of your antenatal schedule, our Bump Circle journal at /blog has further plain-English guides to pregnancy appointments and what typically happens at each stage. As always, anything specific to your own pregnancy or your baby's development is best discussed directly with your midwife or maternity team, who know your individual circumstances.