Fetal stimulation by pulsed diagnostic ultrasound.
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.


CONCLUSIONS
Diagnostic ultrasound may stimulate fetal body motion.
Fatemi
M
M
Department of Basic Ultrasound Research, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
Ogburn
P L
PL
Greenleaf
J F
JF
D005260:Female; D005323:Fetal Monitoring; D005324:Fetal Movement / Q000502:physiology; D005333:Fetus / Q000502:physiology*; D006340:Heart Rate, Fetal; D006801:Humans; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D018617:Ultrasonography, Doppler, Pulsed; D016216:Ultrasonography, Prenatal