Nyman et al, Vibroacoustic stimulation in risk pregnancies


Original articles

J. Perinat. Med. 20(1992)267-274

Vibro-acoustic stimulation in high-risk pregnancies; maternal perception of fetal movements, fetal heart rate and fetal outcome Margareta Nyman1, Sabaratnam Arulkumaran3, Jan Jakobsson1, and Magnus Westgren2

Department of Obstetrics and Gynaecology, Department of Anesthesiology, Karolinska Institutet, Danderyd Hospital, Danderyd, Sweden, Department of Obstetrics and Gynaecology, Karolinska Institutet, Huddinge Hospital, Huddinge, Sweden, Department of Obstetrics and Gynaecology, National University Hospital, Singapore

1 Introduction

2 Material and methods

Vibro-acoustic stimulation of the fetus has been used during the past decade for assessing fetal status, for rendering a non-reactive trace on the non-stress test (NST) reactive [2, 3, 6, 15], and for inducing fetal movements [8, 13, 16].

The series studied comprised 517 high-risk patients (with 534 fetuses) admitted to the Department of Obstetrics and Gynaecology, Danderyd Hospital, Karolinska Institutet, in the period, 1986 — 89. The principal diagnoses, the modes of delivery and perinatal outcome are presented in tables I, II and III, respectively. The women were between 17 and 47 years old (median 30). Parity ranged between 0 and 6 (median 0). There were two stillbirths. In one case (a diabetic) the patient had undergone unsuccessful induction of labour with prostaglandins the day before. All previous FHR tracings had been consistently normal, as had the patient's blood glucose concentration. No FAST had been performed during the days preceding the intra-uterine death. The other case was a primipara admitted for pre-eclampsia, who had a normal NST result two days prior to the intra-uterine fetal death.

The efficacy of vibro-acoustic stimulation with an electronic artificial larynx in producing fetal movements has been demonstrated by several investigators [5, 10]. The fetus responds to the stimulation in utero much as the newborn reacts in the startle reflex [14]. Maternal perception of fetal movements is the simplest way of recording them. In a previous study at our department, where maternal perception of sound-provoked fetal movements was compared to the results of fetal heart rate (FHR) tracings and to perinatal outcome, a significant correlation was found between absence of fetal movements and fetal distress [19]. In the present descriptive study, this fetal acoustic stimulation test (FAST) was included as a part of the clinical routine in the management of high-risk pregnancies. Its sensitivity and specificity, and its predictive value visa-vis a non-reactive FHR tracing and a reduced Apgar score are reported and the attitude of patients and personnel to the test are commented upon.

1992 by Walter de Gruyter & Co. Berlin · New York

The vibro-acoustic stimulation was given in direct connection with the FHR-monitoring, usually when the monitoring had been in progress for a few minutes. The tests were made at any time of day, depending on access to the FHR monitor and the admission time of the patient. The test was performed as previously described [19], with the patient semi-recumbent, the electronic artificial larynx (Servox, Siemens, ColBrought to you by | University of Arizona Authenticated Download Date | 5/27/15 5:13 AM


Nyman et al, Vibroacoustic stimulation in risk pregnancies

Table I. Indications for admission Diagnosis

No. of patients

Pre-eclampsia and hypertension IUGR or suspected IUGR Bleeding, including abruption and placenta praevia Diabetes and gestational diabetes Reduced fetal movements Post-term PROM and/or premature contractions Multiple pregnancy Medical disorders Others Total

164 68 49


and 160 beats per minute. A pathological FHR was defined as a non-reactive tracing. Tachycardia or bradycardia and decelerations could be present or absent. Evaluation of the FHR tracing was done by the physician in charge. Not all patients underwent the FAST, either due to the short time they spent at the ward (sometimes only a few hours), or to changes of staff with new midwives unaccustomed to the test procedure. Approximately 80% of the patients admitted to the ward were examined with the FAST during the study period. They who did not undergo the FAST were similar to the FAST group in age, diagnoses and perinatal outcome.

35 61 17 26 8 48 41 517

On 24 occasions (i.e., 1,2%) the patient refused to undergo the FAST, because of previous discomfort due to vigorous fetal response in some cases, while in others the gravida did not wish to expose the fetus to "unnatural disturbance".

= intrauterine growth retardation = premature rupture of membranes

Table Π. Mode of delivery Mode of delivery

No. of children


Spontaneous vaginal delivery Low Caesarean section Ventouse Forceps Total

315 197 21 1 534

59 37 4

3 Results

Table ΠΙ. Perinatal outcome Apgar score

Vibro-acoustic stimulation in high-risk pregnancies; maternal perception of fetal movements, fetal heart rate and fetal outcome.

Maternal perception of fetal movement in response to vibro-acoustic stimulation was compared with antenatal fetal heart rate monitoring as a test of f...
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