Mid pregnancy scan

The purpose of the mid pregnancy scan (sometimes known as a 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

The mid-pregnancy screening scan is used to look for health conditions or chromosomal conditions affecting the development of your baby's:

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

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 conditions 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 conditions or chromosomal conditions that haven't been picked up through the scan.

If the scan is inconclusive

Most people find that their baby's developing well.

If the sonographer is unsure of something, they may ask for a second opinion from another sonographer or doctor.

If this happens, they’ll tell you what they’re checking for but they may not be sure yet.

Pre-natal support and treatment planning

Finding out about health conditions or chromosomal condition 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.

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 no conditions are found on the mid-pregnancy screening scan, you probably will not need another scan during your pregnancy.