Biomedical subjects
Publications and source records attributed to C F van Heteren.
Observation of the fetal movement and fetal heart rate responses to repeated vibroacoustic stimulation might be useful as a measure to assess fetal well-being. Studies of abnormal fetuses are needed to gain insight in the spectrum of possible responses to stimulation. We present a case of a fetus with trisomy 18 that failed to respond to repeated stimulation.
OBJECTIVES: Testing of fetal habituation to repeated vibroacoustic stimulation might give additional information concerning the fetal condition and central nervous system (CNS) functioning in postterm pregnancies. This study is designed to investigate whether healthy postterm fetuses are able to habituate and if so, if the habituation pattern of postterm fetuses differs from that of term fetuses. STUDY DESIGN: Twenty women with an uncomplicated pregnancy beyond 41 weeks gestational age (GA) participated, and 37 women with a GA between 37 and 40 weeks served as controls. The vibroacoustic stimulus was repeatedly applied to the maternal abdomen above the fetal legs for a period of 1s every 30s. A fetal trunk movement within 1s of stimulus application was considered a positive response. Lack of response to four consecutive stimuli indicated habituation. The habituation rate is defined as the number of stimuli applied before the fetus stopped responding. Data were compared using Mann-Whitney U test. RESULTS: Of the 18 postterm fetuses in which the presence or absence of habituation could be established, 14 habituated and four persisted in responding. Twenty-six of the 32 term fetuses, in which the presence or absence of habituation could be established, habituated and six persisted in responding. The habituation rate varied widely in postterm (median of eight stimuli, quartile ranges of 6 and 18) as well as in term fetuses (median of 9.5 stimuli, quartile ranges of 6 and 15). There was no difference in median habituation rate between postterm and term fetuses. CONCLUSION: The ongoing maturation of the CNS in the last weeks of pregnancy appears not to be reflected in the fetal habituation pattern. Furthermore, the interfetal variability in habituation of healthy postterm fetuses is such that testing of habituation appears not to be suitable for the identification of the fetus at risk for an adverse neonatal outcome.
OBJECTIVES: Fetal habituation to repeated stimulation has the potential to become a tool in the assessment of fetal condition and of the function of the fetal central nervous system (CNS). However, the influence of fetal quiescence and activity on habituation remains to be clarified. We studied habituation and the influence of fetal state and fetal heart rate (FHR) parameters on habituation in healthy term fetuses. SUBJECTS AND METHOD: We studied habituation in 37 healthy fetuses in two tests with an interval of 10 min. The vibroacoustic stimuli were applied to the maternal abdomen above the fetal legs for a period of 1 s every 30 s. A fetal trunk movement within 1 s after stimulation was defined as a positive response. Habituation rate is defined as the number of stimuli applied before an observed non-response to four consecutive stimuli. The FHR patterns (FHRP) of the 10 min observation period before and after the tests were visually classified. Fetal states were defined according to the FHRP. Baseline FHR, FHR variability and the number of accelerations were calculated in a subgroup of 25 fetuses. RESULTS: Of the 32 fetuses that responded normally during the first test, 26 habituated and six had persistent responses. The median habituation rate decreased significantly in the second test (P=0.001). There was no difference in habituation rate between fetuses that where initially in a quiet state and those in an active state. The FHR parameters before the first test and the difference between these FHR parameters before and after the test did not correlate with the habituation rate. CONCLUSIONS: Although the majority of healthy fetuses was able to habituate, the interfetal variability in habituation performance is such that testing of habituation seems not to be a sensitive tool for the assessment of the fetal CNS. This variability is neither the result of differences in fetal state nor of the various FHR parameters before testing, nor of the difference in change of FHR parameters arising from stimulation.
We used fetal habituation to repeated vibroacoustic stimulation to assess fetal memory. After the initial stimulus, we assessed the fetuses 10 min later and again after 24 h. 16 of 19 fetuses habituated rapidly to the stimuli at 10 min (p=0.004) and 24 h (p=0.042) after the initial test. We conclude, therefore, that fetuses are able to learn: they have a short-term memory of at least 10 min, and a long-term memory of at least 24 h.
BACKGROUND: Observation of fetal movement and fetal heart rate (FHR) responses to repeated vibroacoustic stimulation (VAS) might be useful as a measure to assess fetal well-being and to assess the integrity of the fetal central nervous system (CNS). We observed the movement and FHR responses to repeated VAS of a term fetus with a serious brain anomaly as compared to responses of normal term fetuses. SUBJECTS, METHODS, RESULTS: In 37 normal term fetuses and in a term fetus with an encephalocele we studied movement and FHR response to repeated VAS. All normal fetuses responded within 1 s after stimulation with general body movement and FHR acceleration. At 36 gestational weeks, no movement or FHR responses were seen in the fetus with an encephalocele. Repetition of the test in this fetus after one week still showed no response to repeated VAS. CONCLUSION: Normal fetuses showed movement and FHR responses to external stimulation. The fetus with an encephalocele did not respond to repeated VAS with a movement or FHR acceleration. Case studies in fetuses with structural anomalies of the CNS are needed to gain insight into the spectrum of possible responses to VAS.
In three women, aged 28, 35, and 38 years, with multiple pregnancies and discordant foetal growth, the question arose what to do in case of (threatening) intrauterine death of one twin. In one monochorionic pregnancy with single foetal death the survivor suffered irreversible neurological damage and died at the age of five months, in one monochorionic pregnancy the survivor was born healthy and in one dichorionic pregnancy both twins were born healthy although one twin showed severe intrauterine growth retardation. The problem concerning single foetal death in a monochorionic pregnancy is whether to terminate the pregnancy and accept the risk of premature birth to the surviving twin, or to continue the pregnancy and accept the risk of damage to the survivor. In a dichorionic pregnancy foetal death of one twin does not entail any great risk of damage to the survivor; in such a pregnancy single foetal death in a premature phase may be accepted and the pregnancy may be continued. Sonographic determination of the chorionicity in multiple pregnancy at an early stage is essential because it also determines the policy if foetal problems occur.
OBJECTIVE: To determine neonatal outcome of surviving twins in pregnancies complicated by twin-twin transfusion syndrome and fetal deaths of co-twins. METHODS: We retrospectively reviewed medical records of 11 women seen during 1990-1996 in our hospital who had pregnancies complicated by twin-twin transfusion syndrome and death of one fetus. RESULTS: The median interval between fetal death and delivery (six by cesarean delivery and five vaginally) was 2 weeks (range, 1 day to 7 weeks). Three of the 11 surviving twins died soon after birth (gestational ages at birth 32, 31, and 34 weeks; fetal death-delivery intervals 3, 7, and 7 weeks, respectively). Two survivors were severely handicapped (gestational ages at birth 29 and 33 weeks; fetal death-delivery interval 1 and 2 weeks, respectively). Two children showed cerebral echodensities on ultrasound after birth but developed normally, and four did not show any abnormalities on cerebral and abdominal ultrasound and developed normally. Five of 11 surviving twins, each born 1 week or more after fetal death of the co-twin, either died or experienced serious morbidity. In the two infants born within 1 day of fetal death, no problems were detected. CONCLUSION: In monochorionic twin gestations complicated by twin-twin transfusion syndrome, approximately half of surviving twins will experience mortality or serious morbidity when co-twins die in utero.