Screening for Down's syndrome will happen at the dating scan if: The screening test for Down's syndrome used at this stage of pregnancy is called the combined test.

The combined test involves a blood test and measuring the fluid at the back of the baby's neck (nuchal translucency) with an ultrasound scan.

Movements such as fetal heart beat and malformations in the feus can be assessed and measurements can be made accurately on the images displayed on the screen.

Such measurements form the cornerstone in the assessment of gestational age, size and growth in the fetus.

The transvaginal ultrasound probe is thin, about 2cm diameter.

The probe is covered with a disposable protective sheath.

A small amount of ultrasound gel is placed on the end of this probe.

3-D Ultrasound – Uses specially designed probes and software to generate 3-D images of the developing fetus.

4-D or Dynamic 3-D Ultrasound – Uses specially designed scanners to look at the face and movements of the baby prior to delivery.