Journal of Ultrasound in Medicine, Vol 20, Issue 8 883-889, Copyright © 2001 by American Institute of Ultrasound in Medicine
Fetal stimulation by pulsed diagnostic ultrasound
M. Fatemi, P. L. Ogburn Jr and J. F. Greenleaf
Department of Basic Ultrasound Research, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
OBJECTIVE: To show that pulsed ultrasound from a clinical ultrasonic
imaging system can stimulate the fetus. Stimulation is defined mainly as
increased fetal gross body movements in response to excitation. METHODS:
Fetuses of a group of 9 volunteer women (mean gestational age, 33.37 weeks;
range, 25-40 weeks) were evaluated for body movement under 3 different
conditions: (1) control, with no ultrasound exposure; (2) ultrasound in
continuous wave Doppler mode; and (3) pulsed ultrasound in pulsed Doppler
and B modes. A conventional external fetal monitor, with negligible
ultrasonic output, was used to monitor fetal gross body motions. After an
initial rest period of 3 minutes with 1 or no fetal motion, fetuses were
monitored for an additional 3 minutes under the exposure criterion defined
for each condition. Resulting fetal motions under the 3 conditions were
compared using the Wilcoxon signed rank test. RESULTS: The test showed that
fetuses moved significantly more frequently under condition 3 (mean +/- SD,
3.43 +/- 1.93 movements per minute) than under condition 1 (0.40 +/- 7.33
movements per minute) or condition 2 (0.63 +/- 7.67 movements per minute);
P = .004 and .016, respectively. Fetal movements under conditions 1 and 2
did not differ significantly. CONCLUSION: Diagnostic ultrasound may
stimulate fetal body motion.
