Vibroacoustic stimulation in abnormal biophysical profile: Verification of facilitation of fetal well-being

Abstract

Objectives To verify the effect of vibroacoustic stimulation on biophysical profile score, with a prospective randomised study. Study design All women with singleton pregnancy, gestational age ≥ 30 weeks, intact membranes and biophysical profile score ≤ 8/10 entered the study, after giving written consent, and were randomised to two groups. In group A, a 3-s stimulus with an artificial larynx was applied; if biophysical profile remained abnormal for 30 min, a second stimulus was applied and it was assessed again. In group B, the observation time was extended for 60 min to match the time periods of group A. Pregnancies were managed by final test score and patients delivering more than 24 h apart from last examination were disregarded from the study. Outcome criteria were intrauterine deaths, caesarean sections for fetal distress, Apgar score < 7 at 5 min postpartum, meconium-stained amniotic fluid and neonatal intensive care unit admissions. Our null hypothesis was that application of vibroacoustic stimulation does not alter test's statistical parameters. Results 1349 patients were randomised in group A and 1484 in group B (2833 in total). When comparing group A to B, application of vibroacoustic stimulation significantly decreased the number of positive tests (4.74% vs. 6.67%, p < 0.05) and increased the prevalence of outcome criteria in this subgroup (positive likelihood ratio: 24.1 95% CI: 11.12–52.46 vs. 7.52 95% CI: 4.93–11.46), without altering perinatal outcome. Furthermore, specificity, positive predictive value and test accuracy were significantly improved, as well as negative predictive value for intrauterine death. Conclusion Vibroacoustic stimulation improves the efficiency of biophysical profile score by decreasing false positive tests and improving test accuracy and should be considered as a means of a more thorough fetal evaluation when fetal compromise is suspected.