Imaging
Dating Scan
A dating scan is an ultrasound in early pregnancy that confirms how many weeks pregnant you are and checks the baby’s development.
Quick answer
Dating Scan: what it is and what the results mean
A dating scan is an ultrasound examination, usually around 8 to 14 weeks of pregnancy, that measures the baby to estimate the due date, confirms the pregnancy is developing and checks whether there is more than one baby.
- Why it is done: It is done to accurately date the pregnancy, check the baby’s heartbeat and development, detect twins or more, and — when combined with a blood test and neck measurement — form part of screening for chromosomal conditions.
- Understanding results: The sonographer measures the baby to estimate the due date and checks development.
What it is
A dating scan is an ultrasound examination, usually around 8 to 14 weeks of pregnancy, that measures the baby to estimate the due date, confirms the pregnancy is developing and checks whether there is more than one baby.
Why it is done
It is done to accurately date the pregnancy, check the baby’s heartbeat and development, detect twins or more, and — when combined with a blood test and neck measurement — form part of screening for chromosomal conditions.
What to expect
You usually attend with a full bladder. Gel is applied to your tummy and a probe is moved over it to produce images on a screen. It is painless and takes about 20–30 minutes; sometimes an internal scan gives a clearer view.
Understanding the results
The sonographer measures the baby to estimate the due date and checks development. Most scans are reassuring; occasionally further scans or tests are arranged if anything needs a closer look.
Good to know
Risks and limitations
Ultrasound is considered safe in pregnancy with no known harm. A dating scan is not a detailed check for physical abnormalities, which is the purpose of the later anomaly scan.
Education and reference only. This explains the test in general terms and is not medical advice. Always follow the specific instructions from the team arranging your test, and discuss your results with your clinician.
Answers
Dating Scan: frequently asked questions
Why do I need a full bladder for the scan?
A full bladder lifts the womb into a better position and improves the ultrasound view in early pregnancy, giving clearer images of the baby.
Can the dating scan detect abnormalities?
It mainly confirms dates, the heartbeat and the number of babies. A detailed check for physical abnormalities is done later, at the 20-week anomaly scan.
Related tests
Other imaging investigations
Sources
Where this is drawn from
- NHS — Screening and pregnancy
- NICE — antenatal and screening guidance
- UK National Screening Committee
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