Statement on the Safe Use of Doppler Ultrasound During 11-14 week scans (or earlier in pregnancy)

The use of Doppler ultrasound during the first trimester is currently being promoted as a valuable diagnostic aid for screening for and diagnosis of some congenital abnormalities. The procedure requires considerable skill, and subjects the fetus to extended periods of relatively high ultrasound exposure levels. Due to the increased risk of harm, the use of spectral Doppler ultrasound with high TI in the first trimester should be viewed with great caution. Spectral Doppler should only be employed when there is a clear benefit/risk advantage and both TI and examination duration are kept low. Protocols that typically involve values of TI lower than 1.0 reflect minimal risk. In accordance with the WFUMB statement, we recommend that:

1. All scans should begin at a displayed TI of 0.7 because the total duration of an ultrasound examination during pregnancy cannot be known in advance. Higher outputs should be used only if needed to obtain adequate images and in accordance with the As Low As Reasonably Achievable (ALARA) principle.

2. Pulsed Doppler (spectral, power, and color flow imaging) ultrasound should not be used routinely.

3. Pulsed Doppler ultrasound may be used for clinical indications such as to refine risks for trisomies.

4. When performing Doppler ultrasound, the displayed Thermal Index (TI) should be less than or equal to 0.7 provided adequate images can be obtained, and exposure time should be kept as short as possible consistent with acquisition of needed clinical information.

5.  When using Doppler ultrasound for research, teaching, and training purposes, the displayed TI should be less than or equal to 0.7, and exposure time should be kept as short as possible consistent with the purposes of the scan. Informed consent should be obtained.

6.  In educational settings, discussion of first trimester pulsed or color Doppler should be accompanied by information on safety and bioeffects (eg, TI, exposure times, and how to reduce the output power).

7. When scanning maternal uterine arteries in the first trimester, there are unlikely to be any fetal safety implications as long as the embryo/fetus lies outside the Doppler ultrasound beam.


Approved: 04/18/2011; Reapproved: 03/21/2016, 10/30/2016

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