Vibroacoustic stimulation for fetal assessment in labour in the presence of a nonreassuring fetal heart rate trace: Cochrane systematic review

Abstract

Assessed as up to date: 2012/09/07

Background

Fetal vibroacoustic stimulation (VAS) is a simple, non-invasive technique where a device is placed on the maternal abdomen over the region of the fetal head and sound is emitted at a predetermined level for several seconds. It is hypothesised that the resultant startle reflex in the fetus and subsequent fetal heart rate (FHR) acceleration or transient tachycardia following VAS provide reassurance of fetal well-being. This technique has been proposed as a tool to assess fetal well-being in the presence of a nonreassuring cardiotocographic (CTG) trace during the first and second stages of labour.

Objectives

To evaluate the clinical effectiveness and safety of VAS in the assessment of fetal well-being during labour, compared with mock or no stimulation for women with a singleton pregnancy exhibiting a nonreassuring FHR pattern.

Search methods

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (6 September 2012) and reference lists of all retrieved articles. We sought unpublished trials and abstracts submitted to major international congresses and contacted expert informants.

Selection criteria

All published and unpublished randomised trials that compared maternal and fetal/neonatal/infant outcomes when VAS was used to evaluate fetal status in the presence of a nonreassuring CTG trace during labour, compared with mock or no stimulation.

Data collection and analysis

Two review authors independently sought to assess for inclusion all the potential studies we identified as a result of the search strategy. We planned to resolve any disagreement through discussion or, if required, to consult a third person. Where there was uncertainty about a particular study, we attempted to contact study authors for additional information. However, these attempts were unsuccessful.

Main results

The search strategies yielded six studies for consideration of inclusion. However, none of these studies fulfilled the requirements for inclusion in this review.

Authors' conclusions

There are currently no randomised controlled trials that address the safety and efficacy of VAS used to assess fetal well-being in labour in the presence of a nonreassuring CTG trace. Although VAS has been proposed as a simple, non-invasive tool for assessment of fetal well-being, there is insufficient evidence from randomised trials on which to base recommendations for use of VAS in the evaluation of fetal well-being in labour in the presence of a nonreassuring CTG trace.

Author(s)

East Christine E, Smyth Rebecca MD, Leader Leo R, Henshall Naomi E, Colditz Paul B, Lau Rosalind, Tan Kelvin H

Summary

Vibroacoustic stimulation for fetal assessment in labour in the presence of a nonreassuring fetal heart rate trace

Vibratory and sound stimulation may help to tell how well a baby is during labour when the heart beat is showing possible concerns.

A baby's heart rate is checked during labour to try to identify babies who are having difficulties. However, changes in the baby's heart-rate patterns may not always mean the baby really is having difficulties. When the heart-rate pattern is not reassuring, extra tests may help to indicate which babies need help. Sound and vibratory stimulation (fetal vibroacoustic stimulation) is one such test. For healthy babies it produces a positive response, and absence of this could be a sign that the baby is having difficulty. The review authors found no randomised trials that considered vibroacoustic stimulation for this use. More research would be helpful.

Reviewer's Conclusions

Implications for practice

There are currently no randomised controlled trials that address the safety and efficacy of fetal vibroacoustic stimulation (VAS) following demonstration of a nonreassuring cardiotocograph (CTG) during labour. Although VAS is a simple, non-invasive test of fetal well-being, there is insufficient evidence from randomised trials to show whether VAS is effective in the evaluation of fetal well-being during labour.

Implications for research

Well conducted randomised controlled trials addressing the safety and effectiveness of VAS during labour are required before intrapartum VAS can be considered to have been adequately evaluated. Outcomes of interest could include those listed in this review. The primary outcome may be long-term neurodevelopmental disability: however, at least in the term fetus population, it is an adverse outcome of such low prevalence that any change would be difficult to power without a prohibitively large sample size. An outcome of clinical relevance may be as simple as the number of additional tests performed to assess fetal well-being following identification of a nonreassuring CTG, through to operative delivery rates.

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