Pregnancy

What is the anomaly scan and when does it happen?

Q: What is the anomaly scan and when does it happen?

The anomaly scan is offered between 18 and 21 weeks and checks your baby's physical development in detail — the brain, spine, heart, kidneys, limbs and more, across around 11 areas the NHS screens for specific conditions. It also checks the placenta's position. Most scans find everything developing as expected; if something needs a closer look, you'll be offered further tests, not an immediate diagnosis.

What's actually checked

Sonographers work through a standardised checklist covering the baby's head and brain, face, spine, heart, stomach, kidneys, bladder, arms, legs and umbilical cord insertion, plus placenta position (relevant for birth planning if it's low-lying). It typically takes 20–45 minutes.

What it can and can't tell you

The anomaly scan screens for specific, defined conditions — it isn't a general guarantee of a healthy baby, and it can't detect every possible condition. If a marker is seen, it usually means "worth a closer look" rather than a diagnosis; most follow-ups conclude nothing is wrong.

Practical notes

You can usually find out the baby's sex at this scan if you want to, though the sonographer's focus is the anomaly check first — ask early in the appointment. A full bladder isn't required (unlike the dating scan), and one support person can typically join you; check your unit's current visitor policy.

Health answers describe NHS guidance and are not medical advice — for anything urgent, call 111 (or 999 in an emergency). Spotted something out of date? Email editors@clevermum.co.uk.