Vibroacoustic stimulation enhances visualization of the four-chamber cardiac view in the third trimester

The objective of this study was to determine whether vibroacoustic stimulation would improve the visualization rate of the four-chamber cardiac view. Patients between 26 and 42 weeks' gestation were considered to be candidates for this study if the amniotic fluid index (AFI) was between 8.0 and 24.0 cm, no malformations were detected on a careful fetal anatomical survey and a four-chamber cardiac view was not obtainable. Once a four-chamber view was considered to be not obtainable due to fetal position, the patient was asked to withdraw a sealed envelope and was assigned to either the study or the control group. The 164 study patients received one to three 3-s vibroacoustic stimulations. Five minutes later a second attempt was made to visualize the four-chamber view adequately. The control group consisted of another 198 subjects in whom a four-chamber view could not be obtained. The control group did not receive vibroacoustic stimulation. A similar 5-min time interval was allowed to elapse before an attempt was made to visualize the four-chamber view. The study and control groups were similar with respect to fetal presentation, placental location, fetal weight category, biophysical profile score, gestational age, AFI and estimated fetal weight. The rate of the four-chamber view was significantly higher among fetuses receiving vibroacoustic stimulation (20.1%), in comparison to the control group (11.1%) (p = 0.019). Successful repositioning was more likely among fetuses with estimated fetal weight between 2251 and 3050 g, and at a gestational age between 33.1 and 37.0 weeks. We conclude that in a selected group of patients vibroacoustic stimulation can be used to enhance visualization of the four-chamber view.