A prospective cohort study to evaluate the feasibility and accuracy of Fetal Vibroacoustic Stimulation as prenatal hearing screening tool

Although neonatal screening tests for hearing loss are available, prenatal screening tests for the assessment of hearing loss are currently not routinely performed. The detection of hearing loss in the prenatal period might allow in earlier detection and management of hearing loss, given that the development of the auditory system begins in the fetal period as early as the 16th weeks of gestation. We therefore would like to assess if Fetal Vibroacoustic Stimulation as prenatal hearing screening tool could be more practical and effective tools for early detection of hearing loss.•                Optimal intensity, frequency and tools for vibroacoustic stimulation (by study on 10 fetuses) 2000Hz at 85dB, 90dB, 95dB will be finalised before the beginning of the study on the recruited patients.

•                Pregnant women (fulfilling the inclusion and exclusion criteria) from antenatal clinic/ admitted in the in-patient ward under the department of O&G will be recruited

•                In a relatively quiet room, routine USG will be done, fetal movements will be noticed and confirmation will be made that the fetus is not in the sleep mode. In case the foetus is found to be in sleep mode, it would be gently stimulated with external movement.

•                The maternal abdominal wall thickness, liquor volume, fetal position, location of the fetal heart and head (pinna) will be noted down.

•                The VAS stimuli will be produced directly over the abdominal wall overlying the fetal head/ pinna.

•                Comparison will be made before and after administration of VAS with a commercially available battery operated fetal acoustic stimulation device

•                Three times the VAS will be conducted for 10 seconds each with 60 seconds interval between them to see the response of the fetus.

•                Fetal heart rate variance and Fetal movements – gross body movements, isolated limb movements, breathing movement and startle response including the number and types will be noted

•                Fetal movements, heart rate accelerations from the baseline for next 60 secs will be noted following the VAS.

•                Positive response will be considered if the foetus responses to atleast one of stimulus.

•                The typical foetal response to a loud and sudden sound includes a short latency heart rate (H.R) acceleration averaging 15 beats per minute, usually accompanied by limb movements, change in position and eyeblinks and this typical foetal response will be defined as positive response.

•                In case of absence of a positive response, the test would be repeated the next day for admitted patients/ next antenatal visit for out-patient patients.

•                The qualifications and experience of the obstetrician performing the test will also be noted down.

•                The total time taken for performing the screening tests will be noted down.

•                Following the prenatal screening till the delivery and during the peripartum period, the following points will be noted- Administration of ototoxic drugs to mother or baby, fever with rash in the mother, type of delivery, peripartum events, delayed cry, birth weight, neonatal jaundice, NICU stay, ventilator support requirement for the baby etc.

•                Following birth of the baby screening for hearing via OAE, BERA/ABR and OAE + BERA/ABR (BERA as the gold standard for patients with hearing loss on screening test) bedside will be compared to fetal vibroacoustic stimulation to find accuracy of fetal vibroacoustic stimulation as a prenatal hearing screening tool

•                In case the baby failed the prenatal/ neonatal/ both screening for hearing loss, comprehensive hearing test of the baby will carried out in the form of BERA, ASSR and OAE.

•                Assessment of inter-observer discrepancy (Resident Vs Faculties) and Evaluation of the extra time taken for this test by different observers

•                Maternal physical discomfort/pain during this study, maternal emotional concerns during/ for this test, maternal/ parental acceptance of this test will be evaluated by asking a set of three questions about their experience of the test procedure which are –

•                Would you agree to get tested with VAS for your fetal hearing screening?

·                Yes/ no

·                If no then the reason

●               Was the procedure painful?

If yes, then the score in VAS

●               Would you consider the retesting with VAS in future just prior to the birth of your child?