If you have ultrasound in the early weeks of pregnancy, you may be asked to drink plenty of fluid; an enlarged bladder makes it easier to scan for a tiny fetus. You will lie on a bed beside the machine and lift up your clothes - wear something loose. The procedure takes about 20 minutes.
The machine The screen shows an image of the fetus from which the necessary measurements are taken
The screen image The image is not always clear. The technician will point out the head, heart and limbs. This scan shows an 18-week fetus.
The scan operator Ultrsound may be done by a radiographer, an ultrasonographer, or a doctor or midwife