What Do Ob/Gyn Residents and Fellows Know About Ultrasound Safety?

Although ultrasounds are relatively safe and have become integral tools in medicine, the underlying thermal and mechanical mechanisms have the potential for causing negative biological effects. To protect patients, the National Electrical Manufacturers Association developed standards requiring the on-screen display of thermal indexes (TI) and mechanical indexes (MI) on machines capable of producing MIs or TIs greater than 1. But do residents and fellows know about and utilize these safety measures?

Dr Laura E. Houston, of the Department of Obstetrics and Gynecology, Washington University in St. Louis, and colleagues submitted electronic surveys to all accredited obstetrics and gynecology residency and maternal-fetal medicine fellowship programs in the United States during the 2008-2010 academic years. The survey was designed to determine if safety levels were being taught, understood, and implemented in clinical practice and, if so, to what extent.

The response rate was rather low, with the researchers receiving 67 completed surveys from postgraduate year 4 obstetrics and gynecology residents (about 3% of residents) and 92 from maternal-fetal medicine fellows (26%), for a total of 165 responses.

Of the submitted responses, only 13.4% of residents and 20.9% of maternal-fetal medicine fellows knew how to find or use the output display standard, and only 10.9% of residents reported using the output display standard during their ultrasound examinations. Interestingly, 22.7% of fellows reported use of the output display.

Residents and fellows were also unaware of the need to limit the use of ultrasounds during pregnancy. One-third to almost one-half of residents and fellows reported no limitations to the use of obstetric ultrasounds, while 22% to 39% of residents and fellows reported no limitations to the use of Doppler ultrasounds in the first through third trimesters. And, although ultrasound safety knowledge appeared to increase with each year of training, only 34.8% of third-year fellows reported use of the output display standard.

Despite the poor use of the output display, 73% of residents and fellows correctly identified thermal mechanisms as a potential source of harm from ultrasound exposure.

Comparatively, 35% of respondents were able to recognize mechanical mechanisms as potential sources of harm. About 50% of the respondents said they felt comfortable discussing and educating patients about the safety of ultrasound use.

"This study provides evidence that it [ultrasound safety] is not routinely being included in resident education; it appears to be more represented in maternal-fetal medicine fellow education, although not thoroughly," Houston and colleagues noted. "This study provides evidence of the current need to bring ultrasound safety more consistently into obstetrics and gynecology and maternal-fetal medicine fellow education."

 More Information

• National Electrical Manufacturers Association: Standard for Real-Time Display of Thermal and Mechanical Acoustic Output Indices on Diagnostic Ultrasound Equipment, Revision 2
• Obstetric Ultrasound: A Comprehensive Guide to Ultrasound Scans in Pregnancy

References:

Sources

1. Houston LE, Allsworth J, Macones GA. Ultrasound is safe... right? J Ultrasound Med. 2011;30:21-27.
2. vanSonnenberg C. Study: Residents and fellows unaware of ultrasound risks. HealthImaging.com. Published January 1, 2011.