MODEL RELEASED. Pregnancy ultrasound. Doctor carrying out an ultrasound scan of a pregnant woman's swollen uterus (womb). A device called a transducer (in hand, lower right) is moved over the abdomen (bottom right). The transducer emits very-high-frequency sound waves and detects the reflected echoes. The results are used to build an image of the unborn child in the womb. The image will be displayed on a monitor (partially seen at centre right). This safe, non-invasive procedure is used routinely in pregnancy to assess the growth and health of the developing foetus and to detect any abnormalities.