• acoustic noise;
  • four-dimensional ultrasound;
  • mechanical effects;
  • thermal effects;
  • three-dimensional ultrasound

Key content

  • There is a widespread lack of understanding among clinicians regarding the potential risks of magnetic resonance imaging (MRI) and ultrasound energy on the fetus.
  • The use of MRI is not generally advisable during the first trimester of pregnancy.
  • Concerns exist regarding the potential thermal and mechanical effects of ultrasound on the developing embryo/fetus.
  • The use of Doppler ultrasound in the first trimester should be restricted to well-defined diagnostic purposes with the shortest possible exposure duration.

Learning objectives

  • To understand the safety issues of MRI and ultrasound scanning.
  • To understand the potential mechanical and thermal effects of Doppler ultrasound at various stages of pregnancy.
  • To be able to provide women with accurate information about the safety of MRI and ultrasound scanning.

Ethical issues

  • Clinicians should be aware of and trained in the safety issues concerning the use of MRI and ultrasound scans in relation to the stages of pregnancy.

Please cite this article as: Eskandar OS, Eckford SD, Watkinson T. Safety of diagnostic imaging in pregnancy. Part 2: magnetic resonance imaging, ultrasound scanning and Doppler assessment. The Obstetrician & Gynaecologist 2010;12:171–177.