A very full bladder, however, can displace baby and make those important structures and organs difficult to see or fully evaluate. Sometimes the technician may ask you to partially empty your bladder '- and this can be very uncomfortable! Your clinic staff will let you know how much water to drink and how soon before the scan you should drink it.
Safety of Ultrasound
Ultrasound has been studied extensively over 35 years of use. Diagnostic ultrasound uses sound waves at various frequencies, and the low-intensity ranges used in real-time obstetrical scans have never been shown to be harmful to the fetus or mother. Ultrasound, however, should be used only when indicated, and equipment should conform to FDA standards. In recent months, storefront businesses and even kiosks at shopping malls have introduced the "keepsake ultrasound video" and made such scans available to the mass market. Both the American College of Obstetricians and Gynecologists and the Food and Drug Administration have published statements discouraging the use of ultrasound in this way.
Unless complications arise, research confirms the fact that the use of ultrasound does not change the outcome of a pregnancy and, if you're given a choice, one scan performed at 16 to 20 weeks meets the standard of care.