Detail Scan

20-week pregnancy screening scan

This detailed ultrasound scan, sometimes called the mid-pregnancy or anomaly scan, is usually carried out when you're between 18 and 22 weeks pregnant. The scan is a medical examination. You'll be asked to give your permission for it to be carried out.

The 20-week screening scan is offered to everybody, but you do not have to have it if you do not want to.

The scan checks the physical development of your baby, but it cannot pick up every condition.

The 20-week screening scan is carried out in the same way as the NT scan. It produces a 2D black and white image that gives a side view of the baby. This screening programme does not use 3D or colour images.

Make sure you understand what's going to happen, and feel free to ask any questions.

What does the scan look for?
The 20-week screening scan looks in detail at the baby's bones, heart, brain, spinal cord, face, kidneys and abdomen.

It allows the sonographer to look for 11 rare conditions. The scan only looks for these conditions, and cannot find everything that might be wrong.

• Anencephaly
• Open spina bifida
• Cleft lip
• Diaphragmatic hernia
• Gastroschisis
• Exomphalos
• Serious cardiac abnormalities
• Bilateral renal agenesis
• Lethal skeletal dysplasia
•  Edwards' syndrome, or T18
• Patau's syndrome, or T13

In most cases, the scan will show that the baby appears to be developing as expected, but sometimes the sonographer will find or suspect something different.