A RANDOMIZED CONTROLLED TRIAL OF A NEW FETAL ACOUSTIC STIMULATION TEST FOR FETAL WELL-BEING

OBJECTIVES: Our purpose was to determine (1) whether a fetal acoustic stimulation test results in more palpable fetal movement compared with a mock test (control) and (2) whether palpated fetal movements after a fetal acoustic stimulation test are accompanied by a reactive nonstr ess test. STUDY DESIGN: In a randomized controlled trial we studied wo men seen in the labor and delivery suite for various indications. Wome n were excluded for multiple gestation, <31 weeks' gestational age, tr eatment with magnesium sulfate or narcotics, or ruptured membranes. In formed consent was obtained from eligible women, who were then randomi zed to a test or control group. We placed an acoustic stimulator on th e abdomen of each woman, but only the test group was stimulated. We as sessed fetal movement by a grading system: 0 = no fetal movement felt by patient or tester, 1 = fetal movement felt by patient only, 2 = fet al movement felt by tester, 3 = visual movement seen by tester. A posi tive fetal acoustic stimulation test result was defined as one with an y fetal movement felt or seen by the tester (grades 2 or 3). We then p erformed a nonstress test. We compared rates of a positive fetal acous tic stimulation test in the test and control groups with the chi(2) te st. Ap value <0.05 was considered significant. RESULTS: We randomized 297 women to the test group and 280 women to the control (mock test) g roup. Of women tested with the fetal acoustic stimulation test, 81% ha d fetal movement by palpation or visualization (grades 2 or 3) compare d with 19% of the control group (p < 0.0001, odds ratio 19.29, 95% con fidence interval 12.42 to 30.07). Of the test group, 283 (95%) had a r eactive nonstress test and 14 (5%) had nonreactive tests; the control group had 267 (95%) reactive and 13 (5%) nonreactive nonstress tests. Of 242 patients in the test group with a positive fetal acoustic stimu lation test, 236 (98%) had a reactive nonstress test. Of those in the test group with fewer than three contractions per 10 minutes, 164 (89% ) had a positive fetal acoustic stimulation test. Of these, 162 (99%) had a reactive nonstress test. CONCLUSION: The fetal acoustic stimulat ion test evokes significantly more palpated or visualized fetal moveme nt than in controls. Palpated or visualized fetal movement after acous tic stimulation was almost always accompanied by a reactive nonstress test.