Safety in Diagnostic Ultrasound Educational Activities Using Pregnant Patients

Background. The American Institute of Ultrasound in Medicine has long advocated the prudent use of medical ultrasound and has developed safety recommendation statements. These include the following: (1) ultrasound should be used by qualified health professionals to provide medical benefit to patients¹; (2) when examinations are carried out for purposes of research, ultrasound exposures should be as low as reasonably achievable (ALARA) within the goals of the study²; (3) the patient should be informed of the anticipated exposure conditions and how these compare with normal diagnostic practice²; and (4) repetitive and prolonged exposures on a single patient should be justified and consistent with prudent and conservative use.²

Statement. Therefore, prudent and conservative use should also be extended to ultrasound examinations conducted for the purpose of training. Specifically, the following guidelines should be followed:

1. Patient participation should require appropriate informed consent. The primary obstetrician providing prenatal care should be informed of his or her patient’s participation.
2. The patients should be afebrile and prescreened to attempt to avoid unexpected findings.
3. There should be a plan to address unexpected findings should they be observed during the educational activity.
4. There should be no unsupervised first-trimester examinations.
5. Examinations should be performed in a manner consistent with the ALARA principle, including limiting the thermal index (≤0.7)³ and mechanical index (<1.0)* as necessary for educational purposes. The dwell time should be considered and limited.
6. The exposure time, ie, the duration of “hands-on” teaching sessions, should not exceed 1 hour per pregnancy.
7. Exposure to pulsed Doppler ultrasound should be restricted to instructor scanning for short durations only.

*The lung hemorrhage threshold in pigs was between a mechanical index of 1 and 1.9 at 3 MHz.⁴

References

1. American Institute of Ultrasound in Medicine. Official Statements: Prudent clinical use and safety of diagnostic ultrasound. American Institute of Ultrasound in Medicine website. Reapproved May 20, 2019.

2. American Institute of Ultrasound in Medicine. Official Statements: Safety in training and research. American Institute of Ultrasound in Medicine website. Reapproved April 1, 2012.

3. American Institute of Ultrasound in Medicine. Official Statements: Recommended maximum scanning times for displayed thermal index (TI) values. American Institute of Ultrasound in Medicine website. Approved October 30, 2016.

4.  O’Brien WD Jr,  Yang Y,  Simpson DG, et al. Threshold estimation of ultrasound-induced lung hemorrhage in adult rabbits and comparison of thresholds in mice, rats, rabbits and pigs.  Ultrasound Med Biol 2006; 32:1793–1804.