Ultrasound scanning uses sound waves to produce an image of the internal organs. The procedure is routinely used during pregnancy to assess the health of the fetus, determine the fetus’s age, and measure fetal growth. Scanning may also be used to investigate problems, such as vaginal bleeding, and diagnose fetal abnormalities. For example, the procedure may identify neural tube defects and can sometimes detect heart problems. A scan takes about 20–30 minutes and is painless and safe. Doppler scanning may be used to measure blood flow to the fetus.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.