We are pleased to announce extended opening times for Alderley Edge.

What is a Viability Scan?

During pregnancy you’ll be able to have an ultrasound scan at several different stages. The earliest pregnancy scan is the viability scan, which has several purposes.

The viability scan is usually carried out at 6 to 10 weeks. It’s a vaginal scan, which means the transducer probe is inserted internally. This is necessary because at this early stage of the pregnancy, an abdominal ultrasound wouldn’t be powerful enough to detect the tiny baby inside the uterus. A vaginal ultrasound works better at this stage because the probe is closer to the baby and therefore picks up sound waves more effectively.

What does the Viability Scan Check For?

The viability scan is sometimes called the dating scan, although it has other functions in addition to estimating the baby’s due date. The main reasons to have a viability scan are:

  • Predict the gestational age of the pregnancy, and thus the estimated date of birth. This prediction is based on the size of the baby.
  • Determine how many babies are present; for instance whether there are twins or triplets.
  • Confirm the presence of a normal heartbeat.
  • Early detection of certain problems, such as unusual location of the placenta, or the presence of fibroids in the uterus.

How Accurate is the Due Date Estimate?

The earlier a viability scan is performed, the more accurate the due date prediction will be. There are two reasons for this. One is that the baby grows more rapidly early in gestation, so there are large size differences from week to week. The second reason is that foetal size is more variable later in the pregnancy. As the unborn baby develops, genetics and other factors begin to play a role in its size, which makes the due date harder to predict.

If an ultrasound is performed during the first 12 weeks of a pregnancy, it can predict a due date that’s accurate to within 3 to 5 days. For the most accurate due date prediction, the best time to have the viability scan is between 8 and 11 weeks. This is because foetal growth is fastest at this stage of pregnancy, so the size of the baby best indicates the age.

How Important is it to Have a Viability Scan?

A viability scan isn’t essential, but it is a good idea to have one, because it’s the best way to estimate the baby’s due date. This is especially true if your periods are irregular, or if you don’t know the first day of your last period, as these situations make using a pregnancy calculator less accurate. Having a viability scan is important in these cases to confirm the pregnancy as well as to estimate the due date.

Viability Scans at The Birth Company!

At The Birth Company we understand that parents-to-be don’t always have the time to schedule viability ultrasound scans in advance! To help you get your London ultrasound scan ASAP, we offer next-day appointments, and we’re open every day of the week.

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Thank you to all our patients for considering coming to our clinic. We aim to meet the highest standards.

Clinic Locations

Visit our clinic in Central London and Cheshire


137 Harley Street, London W1G 6BF
Nearest Underground Tube Stations

Baker Street
Regent’s Park
Great Portland Street


Alderley Edge Medical Centre, Talbot Road, Alderley Edge, Cheshire, SK9 7HR
Nearest Overground Train Station

Alderley Edge