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Imaging modalities that are used as adjuncts for diagnosis and therapy during pregnancy include sonography, radiography, and magnetic resonance (MR) imaging. Given rapid changes in imaging technology, this chapter is not exhaustive but serves as a guide for imaging obstetric patients with perioperative needs. The focus is on safety, especially with regard to radiation exposure. Thus, detailed dosimetry is provided to help direct examination selection and patient counseling.
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Of all the major advances in obstetrics, the development of sonography for study of both fetus and mother certainly is one of the greater achievements. The technique has become virtually indispensable in everyday practice (Figs. 5-1, 5-2, 5-3).
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Diagnostic sonography uses sound wave transmission at certain frequencies. Recall that ultrasound is a form of nonionizing radiation that transmits energy. Studies involving prolonged ultrasound exposure of animal fetuses suggest that it is possible to induce cellular alterations. For example, with at least 30 minutes of ultrasound exposure to embryonic mouse neurons, a statistically significant number of neurons were impeded from their expected migration (Ang, 2007). At this time, however, the American Institute of Ultrasound in Medicine (2010) and other organizations agree that these findings should not alter the use of ultrasound in pregnant women. Moreover, Naumburg and associates (2000) performed a case-control ...