Browsing by Author "Lindow, Stephen"

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    An assessment of the role of Doppler ultrasound velocity waveform analysis of the umbilical artery in the diagnosis of fetal distress in labour
    (1993) Stuart, Ian Peter; Lindow, Stephen; Van der Elst, Clive
    Introduction: An assessment of the role of Doppler ultrasound velocity waveform analysis of the fetal umbilical arteries in the diagnosis of fetal distress in labour is made from a review of the literature and clinical study. Study objectives: 1) To determine the value of screening with Doppler ultrasound in high-risk labours in the prediction of the development of indicators of fetal distress. 2) To determine whether Doppler velocimetry indices of the umbilical arteries change with the development of indicators of fetal distress in labour. Design: Repeated Doppler velocimetry in selected high risk labours. Setting: Groote Schuur Hospital, Cape Town, South Africa, a large tertiary referral centre. Subjects: Thirty six women with singleton pregnancies complicated either by gestational proteinuric hypertension or by intrauterine growth retardation or both with a normal cardiotocographic tracing at the onset of labour. Main outcome measures: 1) Acid-base status of the fetus was assessed after deli very by analysis of umbilical artery blood. 2) Apgar score was recorded at 1 and 5 minutes. 3) Neonates were carefully examined for clinical signs of perinatal hypoxia. Results: Twenty seven fetuses were followed through labour. No relation was found between umbilical artery Pourcelot ratio (resistance index) on admission in labour and umbilical artery base deficit. Six fetuses were born with an umbilical artery base deficit of more than 10 mmol 1-1. Zero change in mean Pourcelot ratio was noted in both normal and acidotic fetuses. None of the acidotic fetuses showed a change in Pourcelot ratio of more than 0.03. The study had an 80% power to detect a change in mean Pourcelot ratio of 0.07 in the normal fetuses and 0.16 in the acidotic fetuses at a 95% confidence level. No relation was found between Pourcelot ratio on admission in labour or change in Pourcelot ratio during labour and Apgar score. None of the neonates showed clinical signs of perinatal hypoxia. Conclusions: Doppler velocimetry of the umbilical arteries in labour as measured by the Pourcelot ratio does not contribute to the diagnosis of fetal distress in labour.
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    Clinical and ultrasonic estimation of fetal weight
    (1994) Brink, Derek Montagu; De Jong, Peter; Lindow, Stephen
    Several clinical situations occur in obstetrics where it is useful to make an accurate assessment of fetal weight prior to delivery. A foreknowledge of the mass of the fetus can influence management in circumstances complicated by, for example, a previous caesarean section, a breech presentation, a compromised fetus of borderline viability and a diabetic pregnancy at term. Researchers have attempted to estimate fetal weight by assaying oestriol, human placental lactogen, and pregnanediol. These parameters have been found to be of limited value because of the indirect measurement of fetal mass. Since the introduction of ultrasound scanning techniques to obstetrics in the mid- 1960's, it has become possible to visualise the fetus and to make direct measurements of fetal anatomy. By using ultrasound, workers have tried to predict fetal weight by measuring fetal heart volume, hourly urine production, trunk diameter, circumference and placental volume. At present various combinations of head circumference (HC), biparietal diameter (BPD), femur length (FL), and abdominal circumference (AC) are the most commonly used measurements which, when used in different formulas and read off tables estimate fetal weight. Recently the gestational age (GA) has been incorporated into formulas specifically applied to small for gestational age (SGA), appropriate for gestational age (AGA), and large for gestational age (LGA) fetuses. A sonographic estimation of fetal weight based on a model of fetal volume has also been developed. It was generally believed that with the refining of ultrasonic estimation of fetal weight an accurate assessment of fetal mass could, at last, be made. Some investigators believe that the ultrasound estimation of fetal mass is more accurate than clinical assessment. In contrast other workers have shown that the accuracy of clinical examination is comparable to ultrasound determination in estimating fetal weight.
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    The investigation of the calcium antagonist nifedipine on fetal umbilical artery Doppler waveforms
    (1992) Puzey, Martin Stanley; Lindow, Stephen
    The following thesis will describe the investigation of the effect of nifedipine (a calcium antagonist) on the Doppler flow velocity waveform of the umbilical artery. The thesis is divided into two parts. The first section is a literature review of the three main aspects of the thesis namely: 1. The uteroplacental circulation in humans and the pathophysiology related to this circulation in hypertension and intrauterine growth retardation (IUGR). 2. The biokinetics of nifedipine and a review of the experiments that have been performed using the drug in human and animal models. 3. The principles of Doppler ultrasound and the literature pertaining to its use in the study of the uteroplacental circulation. The second part of the thesis is devoted to the effect of nifedipine on fetal umbilical artery Doppler waveform analysis. In the first ·stage of the investigation the effect of the drug on hypertensive mothers has been examined, and in the second stage the effect on fetuses that have an increased resistance index of the umbilical artery Doppler waveform.
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    Maternal hair selenium levels as a possible long-term nutritional indicator of recurrent pregnancy loss
    (BioMed Central Ltd, 2013) Thomas, Viju; Knight, Robert; Haswell, Stephen; Lindow, Stephen; van der Spuy, Zephne
    BACKGROUND:Approximately 1% of all couples trying to conceive will suffer from recurrent pregnancy loss (RPL). Nutritional deficiencies have been postulated as a possible cause of RPL and in particular, selenium deficiency has been associated with reproductive failure in animal studies and more recently, in some human studies. This study was undertaken to assess the maternal hair selenium levels in women with RPL without an identified cause and to compare these results with those of women with successful reproductive histories. METHODS: Twenty four patients with RPL and twenty four control subjects with at least one successful pregnancy and no pregnancy failures, who were matched for age and ethnicity, were recruited. A questionnaire was completed, which included demographic and social information and a dietary history. Hair samples were collected and analyzed for selenium content by inductively coupled plasma mass spectrometry. RESULTS: The control subjects had a higher mean income and had completed more years of education compared with the RPL patients. There was no significant difference in the intake of selenium rich foods between the 2 groups. The patients, however, consumed significantly more fruit, cheese, potatoes and chocolate than the controls. The median (range) selenium content was 0.80ppm (0.19-4.15) and 0.68ppm (0.43-3.76) in patients and controls respectively (Mann Whitney U test 209.5 p=0.74). CONCLUSIONS: While there were significant differences in the 2 groups with regard to resources, education and diet our results show that hair selenium concentrations and dietary selenium intake, were similar in the two groups. Both groups had low levels of this important element.