Mid pregnancy scan (fetal anomaly scan)

The purpose of the mid pregnancy scan (fetal anomaly scan) is to check your baby's health and development.

It's offered between 18 and 21 weeks of pregnancy.

What the scan can show

Some, but not all, potential issues affecting your baby's development can be diagnosed including those affecting:

  • the brain
  • spinal cord
  • heart
  • bowel
  • kidneys
  • limbs

Sometimes minor irregular features of your baby's body are picked up. These usually mean nothing at all, but sometimes a pattern can be seen which might suggest your baby has a health issue.

Ask your midwife if you would like to know full details of the scan's findings.

How accurate is the scan?

Sometimes the sonographer isn't able to get a clear view because of:

  • your baby's position or age
  • the amount of amniotic fluid surrounding your baby
  • your own bodyweight
  • scar tissue left by an abdominal operation, such as a previous Caesarean section

Scans aren’t as reliable at detecting some health issues which:

  • do not affect the appearance of your baby
  • develop later in pregnancy
  • affect your baby’s heart

Although the sonographer and doctors can usually be confident in the findings, no screening test will detect all cases. This means that in a small number of cases, babies are born with health issues that haven't been picked up through the scan.

If they find or suspect an issue

Most people find that their baby's healthy and developing well.

In most cases any issues are minor and the health professional taking care of you will be able to explain them. In rare cases they can be more serious.

If the sonographer is unsure of something, they:

  • may ask for a second opinion from another sonographer or doctor
  • will tell you what the concerns are, but the exact nature or extent of the issue might not be clear at this stage

Can anything be done before the birth?

Finding out about health before birth can help parents get support earlier and make decisions for themselves and their baby. For example, to prepare and plan treatment for after their baby's born.

If your baby may need an operation soon after birth (such as repairing a tummy hernia) it can be arranged for you to deliver your baby in a hospital where this can be done within the first few hours.

Very few health conditions can be operated on before the birth.

Will I need another scan?

You might need another scan if:

  • you take some types of medication
  • you've a long-term medical condition
  • the sonographer isn't able to see everything clearly

If your baby appears to be healthy on the mid-pregnancy scan, you won't need another scan during this pregnancy.

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