Testing for the teratogenicity of pulsed ultrasound in mice

Our replicate of a study by Takabayashi et al. (1981) Effects of pulse-wave ultrasonic irradiation on mouse embryo. Cho-Onpa Igaku (Supersonic Medicine) 8, 286-288 failed to show any effects of exposure in utero of mice to spatial average, temporal maximum intensities of 60 W/cm2. Fetuses were exposed at 8 days post fertilization and assessed at 18 days for fetal weight, resorptions, premature deaths, and malformations. Carrier frequency in the pulse was 2 MHz. Pulse lengths of 10 microseconds and pulse repetition frequencies of 1000 and 200 Hz yielded spatial average, temporal average intensities of 0.6 and 0.1 W/cm2. Total exposure time was 5 min. Our results provide no basis to conclude that conditions relevant to human fetal monitoring will cause developmental, externally visible anomalies in mice exposed as 8-day fetuses.