Dissertations / Theses on the topic 'Ultrasonics in obstetrics Victoria'

Thesis (MTech (Radiography))--Peninsula Technikon, Cape Town, 2000
Ultrasound has, until recently, been regarded as a sophisticated diagnostic modality, reserved for tertiary health care. In reality, it is a cost-effective, reliable and safe modality that is highly suited to primary health care. Secondary level centres provide the only access to ultrasound for many of the obstetric primary health care patients, as primary health care has limited ultrasound resources. The increasing monthly statistics, at one secondary centre, bares witness to the need for ultrasound in primary health care. At the time of this study ultrasound scans were not routine for every obstetric patient. Experience indicates that only the patients who clinically suggest a possible risk are referred for ultrasound to confirm, or rule out problems. However, there are a number of complications, which have little or no early clinical indications. [Palmer, 1995:285] This means that many of the problems encountered are often in late gestation and they have a marked bearing on the obstetric management of the patient. This was a retrospective study, of approximately 1000 patients attending an ultrasound department at a secondary centre. Most of the obstetric patients that were sent for an ultrasound examination came from the primary health care centres in the region.

Three-dimensional (3D) sonography is regarded as a further development of ultrasound imaging technology and its application has greatly increased in recent years. This thesis summarizes the original research findings of the application of 3D ultrasonography for biometry measurement, morphology screening, prenatal diagnosis of abnormalities, ultrasound training and the application of 3D volumetry in the early diagnosis of homozygous α-thalassemia and birth weight prediction in term pregnancy. In a study involving 50 singleton pregnancies at 17-34 weeks' gestation, fetal biometric measurements obtained by an inexperienced operator using both two-dimensional (2D) and 3D ultrasound were reproducible and showed good agreement with those obtained by an experienced operator (all intraclass correlation coefficients were ≥ 0.991). The use of 3D ultrasound by an inexperienced operator allowed faster measurement of fetal biometric parameters than the use of 2D ultrasound, and also seemed to facilitate the acquisition of higher-quality images for the measurement of abdominal circumference. In basic central nervous system and cardiac screening examination, for the inexperienced operator, 3D/four-dimensional(4D) volume acquisition yielded a quicker but less optimal anatomic examination of the fetal central nervous system and heart structures compared to 2D. The diagnostic accuracy of 3D ultrasonography in central nervous system abnormalities was also investigated. The results illustrated that 3D agreed with 2D ultrasonography in the prenatal diagnosis of intracranial malformations. Homozygous α0-thalassemia is very common in South-east Asia and its prenatal diagnosis is essential due to increased fetal and maternal mortality and morbidity. Placental volume/CRL quotient measured by 3D volumetry was significantly higher in pregnancies with α0-thalassemia major cases, and 1.49 may be regarded as a cut-off for early prediction of α0-thalassemia major. In a cross-sectional study of 290 Hong Kong Chinese women with a singleton pregnancy at 37-42 weeks of gestation, the birth weight prediction models based on 3D thigh volume and conventional 2D biometric measurements were developed. It was found that with 3D thigh model, the precision of birth weight prediction to within 5 and 10% of actual birth weight in a Chinese population at term gestation could be achieved. Previous studies have shown that there is a difference in the learning curve of fetal biometry measurement by 2D ultrasound among trainees. Whether there is any difference in the learning curve between 2D and 3D ultrasound is unknown. The study included three trainees and each of them performed 90 scans in biometry measurements. By using cumulative sum analysis graphs, it could be shown that there was no difference in the learning curve between 2D and 3D ultrasound. In conclusion, the above studies have demonstrated that the use of 3D ultrasound has diversified and provided much additional information in selected indications.
published_or_final_version
Obstetrics and Gynaecology
Doctoral
Doctor of Philosophy

In this thesis the use of real-time ultrasound in the assessment and management of preterm labour has been studied, with particular reference to the observation of fetal breathing movements, gross fetal body movements and the state of the uterine cervix. In addition, a longitudinal analysis of the trends in preterm labour in the John Radcliffe Hospital in Oxford between 1973 and 1981 has been performed. Finally, an attempt has been made to clarify the relationship between prostaglandin E2 and fetal breathing movements. The analysis of the trends in preterm labour in Oxford has shown that the incidence of preterm delivery remains unaltered. Of these patients, however, those eligible for tocolytic therapy (unexplained spontaneous preterm labour) form a small proportion. The incidence of extreme prematurity in this group is very low and the neonatal outcome is good. The presence or absence of Fetal Breathing Movements (FBM) by defined criteria is shown to be a highly sensitive index of whether the preterm labour is going to progress to delivery or not in singleton pregnancies with intact membranes. Its significance is lost when the membranes are ruptured and in multiple pregnancies. In pregnancies complicated by antepartum haemorrhage the presence or absence of Fetal Breathing Movements does not predict further haemorrhage leading to delivery. Fetal Breathing Movement status on admission bears no relationship to neonatal outcome and gives no indication of the presence of intrauterine infection. Silent chorioamnionitis has been highlighted as an important cause of "unexplained" preterm labour. Gross Fetal Body Movements (FM) are shown to give no early indication of impending preterm delivery. Evidence is presented to suggest that significant diminution in Fetal Movements is related to poor neonatal outcome. Ultrasonic measurement of the uterine cervix has been found to be technically feasible but of no benefit in the diagnosis of ongoing preterm labour. The relationship between prostaglandin E2 (PGE2) and the cessation of fetal breathing movement has been approached by elucidating the maternal absorption of PGE2 from a vaginal pessary. This then enabled me to sample fetal blood at the time of maximal maternal concentrations (the time we expect the fetal concentration to be greatest). This was performed by fetoscopy and demonstrated that a significant rise in fetal bicycleprostaglandin-E-metabolite (bicyclo-PGEM) occurs following maternal vaginal administration of PGE2. Using this information FBM has been assessed two and a half hours following the vaginal administration of PGE2. Although inconclusive, no reduction in FBM was demonstrated. as the bicyclo-PGE metabolite is used to assess PGE levels, this evidence decreases the probability that PGE mediates the reduction in FBM with the onset of labour.

M.Tech.
It is difficult to manage a pregnancy when fetal age, health status or potential pregnancy risks are not known. The aim of this study was to assess the impact of routine ultrasound screening as compared to selective use of ultrasound in the mid-trimester of pregnancy, on women using South African government health services. The three objectives investigated included assessment of the availability of reliable menstrual histories in the study population, the influence of ultrasound dating on obstetric management and the effect of ultrasound on pregnancy outcome due to the early detection of high risk pregnancies. A cluster randomised trial of 962 women was performed to test the hypothesis that midtrimester routine ultrasound screening in low risk pregnancies would result in improved antenatal care and perinatal outcome. Groups of eligible pregnant women were randomly selected to have either a routine scan followed by normal antenatal care or routine antenatal care which only allows for the selective use of ultrasound, in line with South African Antenatal Care Policy. Statistical analysis of the results confirmed that ultrasound dating is a more accurate predictor of the expected date of delivery when compared to other dating methods. Improved pregnancy dating resulted in a significant reduction in induction of labour for post-term pregnancy in the ultrasound screening group, suggesting a positive effect of ultrasound screening on obstetric management. No improvement was demonstrated in perinatal morbidity or mortality. The early detection of anomalous fetuses only led to one therapeutic abortion. The study did not possess the statistical power to demonstrate improved outcomes when multiple pregnancies were detected early in pregnancy. Currently there appears to be no urgent need to implement a routine antenatal screening programme in the Gauteng public health sector. In view of the fact that a third of the participants indicated that they were unsure of menstrual dates, and one third of the participants in the ultrasound screening group presented with an unreliable menstrual history, it is proposed that unsure dates be considered as a valid indication for the selective use of ultrasound in mid-trimester pregnancy.

M.Tech. (Radiography)
Monitoring the growth and wellbeing of the foetus is a major purpose of antenatal care. The use of diagnostic ultrasound to assess foetal wellbeing has become an important part of prenatal care in both low and high risk pregnancies. Pre-eclampsia and foetal growth restriction (FGR) remains important causes of maternal and perinatal mortality and morbidity. Pre-eclampsia is characterised by an abnormal vascular response to placentation and is a multisystem disorder of unknown cause specific to pregnancy which affects the health of both mother and fetus. Prep-eclampsia complicates between 2 and B % of all pregnancies and is the second most common cause of maternal deaths in the developing world. The aim of this study was to assess the sensitivity of uterine artery spectral Doppler screening in the prediction of pregnancies with a high risk of developing pre-eclampsia or FGR before the clinical onset of the disease. The research objectives were to: 1) Determine the sensitivity of first and second trimester uterine artery spectral Doppler assessment in predicting pre-eclampsia or FGR Identify associations between normal and abnormal uterine artery Doppler waveforms and pregnancy outcomes. 2) Determine the most effective Doppler indices 3) Develop ultrasound management guidelines The data was statistically analyzed to determine the sensitivity of uterine artery Doppler screening. In this study uterine artery Doppler screening performed well. in the risk assessment of the most severe cases of pre-eclampsia and FGR. A larger prospective multicenter trial in South Africa is long overdue and therefore a follow-up study to assess Doppler as a screening tool in a high risk population, as per the guidelines formulated.

MSCAGR (Animal Science)
Department of Animal Science
The main purpose of this study was to assess the efficiency of ultrasonography in monitoring reproductive organs, pregnancy diagnosis, and foetal gender identification and to verify its reliability by laparoscopy and laparotomy, where applicable. Reproductive organs, pregnancy diagnosis and gender of the foetus were examined by A-mode ultrasound using 3.0 - 8.0 MHz trans-rectal transducer. A Sony Olympus Model laparoscope with a camera transducer was used to monitor the reproductive organs and pregnancy diagnosis. In monitoring the follicular dynamics, daily ultrasonography (ULTS) scanning was done for 17 days in sheep and for 21 days in both goats and cattle. Follicles of diameter ≥ 3 mm were selected for analysis of growth, ovulation and regression. For determining the efficiency of the techniques, laparoscopy (LAPSC) and laparotomy (LAPT) were used on days 3 and 10 of the goats and sheep oestrous cycle. The follicles were grouped into three categories according to their diameter as 3 - 4.9 mm, 5 - 7.9 mm and ≥ 8 mm, whereas the follicles of cattle were grouped as 3 - 4.9 mm, 5 - 9.9 mm and ≥ 10 mm. Early pregnancy diagnosis examinations were carried out from day 18 post insemination until pregnancy was confirmed. Foetal gender examinations were conducted from day 40 of pregnancy until the day the gender of the foetus was confirmed. Follicular development was accompanied by the occurrence of waves of follicular growth at different period of the oestrous cycle. The first follicular wave emerged on day 1.0 ± 0.4 in goats, 1.2 ± 0.4 in sheep and 2.2 ± 0.4 in cattle. The maximum diameter of the dominant follicles of observed follicular waves in goats was 7.3 ± 0.4 mm, 6.6 ± 0.2 mm, 7.3 ± 0.2 mm; in sheep was 6.4 ± 0.4 mm, 6.6 ± 0.4 mm and 6.7 ± 0.7 mm and in cattle was 13.1 ± 0.8 mm, 14.2 ± 0.6 mm and 15.7 ± 0.6 mm in wave 1, 2 and 3, respectively. However, the maximum size of the dominant follicle of the ovulatory wave in cattle was larger than the dominant follicles of both first and second waves, but in goats and sheep the dominant follicles were of similar size throughout the waves. In cattle, the ovulatory wave was shorter (p ˂ 0.05) than the duration of the first and second waves, while in sheep and goats were similar throughout the waves. In goats the total number of follicles counted in right and left ovaries under category 3 - 4.9 mm was lower with ULTS and LAPSC than with LAPT method (p ˂ 0.05). In sheep the mean number of follicles between 3 - 4.9 mm category in both right and left ovaries were different (p ˂ 0.05) between ULTS and LAPT. However, for categories 5 - 7.9 mm and ≥ 8 mm in both goats and sheep the mean numbers of follicles observed by all techniques were similar (p ˃ 0.05). In goats, pregnancy diagnosis accuracy improved from zero percent on day 18 to 100% on day 26 - 28, in sheep pregnancy diagnosis was 40% on day 18 and improved to 100% on day 20 - 22 vi of gestation. In cattle accuracy of pregnancy diagnosis was not possible at day 18 and gradually increased to 100% on day 30 - 32 of gestation. Out of 5 (100%) goat’s foetuses whose gender was determined, the diagnosis was correct in 100% (3/3) of the male foetuses and 100% (2/2) of the female foetuses. In sheep two foetuses were sexed as males while the other three were sexed as females and were both 100%. Out of 60% (3/5) of foetuses examined in cattle, 1 (100%) was identified as male and the remaining 2 (100%) were identified as females. The results obtained confirmed that the accuracy for foetal gender by ultrasonography was 100% in all foetuses observed. The current study demonstrated that trans-rectal ultrasonography examination is an efficient method for monitoring follicular dynamics, diagnosing pregnancy and foetal gender identification and that it is as reliable as laparoscopy and laparotomy where they were applied together.
NRF