Biomedical subjects
Publications and source records attributed to R Chaoui.
Using the results of 2,130 assessments with pulsed wave Doppler-ultrasound we established an indication catalogue which reflect the availability in cases of high specificity of the method. The paper shows the modus of fetal monitoring by inclusion of the other obstetrical investigations in consequence of the Doppler-assessment and the frequency of repetition of it.
Using pulsed Doppler, blood flow in the cerebral arteries was measured to assess the fetal central circulation. The Pulsatility-Index (PI) was calculated as a qualitative parameter of flow velocity waveforms. In 418 normal singleton pregnancies we performed 558 measurements between the 27th and 40th week of gestation to get normal range values of the PI. The curve shows a small decrease in the observed interval. In cases of an intrauterine hypoxia the resistance of the central vessels decrease to render the distribution of the fetal blood volume. The result of this is a centralisation of the fetal circulation. 131 high risk pregnancies were investigated and in 21 cases such a centralisation was registered. The fetal outcome of these fetuses was significantly worse compared with fetuses having a normal central flow resistance. We found for example a higher rate of caesarean sections because of fetal distress when the Pulsatility-Index was below the 5th percentile. The sensitivity of the method in prediction caesarean section for fetal distress was 59.3%, the specifity 95.3%.
Explore the source record for details and available documents.
The prenatal detection of congenital heart disease is rather seldom, compared with other fetal malformations. The paper considers the necessity of the development of fetal echocardiography and presents therefore an introduction for the prenatal sonographer. The fetal cardiac characteristics are first analysed, before considering the possibilities and frontiers of the investigation. The different available sonographic methods like the real-time, M-mode, pulsed Doppler and color Doppler are discussed and the importance of each one is emphasized. The indications for fetal echocardiography are further enumerated, as well as the possible consequences resulting from the diagnosis of a heart abnormality. Because of the sophisticated ultrasound devices needed for a precise diagnosis as well as the optimal postnatal care, suspected fetuses have to be referred to centers specialised in perinatal medicine.
Doppler echocardiography was used for the prenatal diagnosis of a double outlet right ventricle and coarctation of the aorta in the 30th week of pregnancy. Heart failure with intrauterine death was observed during blood flow measurements. End-diastolic loss of flow velocity in the umbilical artery and fetal aorta occurred first and was followed by total loss of flow in both vessels, although ineffective contractions of the heart were recorded for a further three minutes. We conclude that a lock of end-diastolic flow velocity in the aorta may not only be due to strong placental resistance but can also be caused by a heart defect of by impaired cardiac function. The four-chamber-view approach makes an accurate prenatal diagnosis of severe congenital heart defects possible.
The patient was referred to hospital in the 29th week of gestation owing to polyhydramnions. Ultrasonography revealed isolated left-sided hypertrophy (from foetal chest to the lower extremity) with subcutaneous lymph cysts. Amniocentesis for genetic examination revealed a chromosomal disorder showing homozygous t(13q, 14q) translocation. This extremely rare anomaly could be explained only and was finally proven by a father-daughter incest. The authors underline the necessity of karyotyping as well as the ultrasonic exclusion of foetal malformations in patients with polyhydramnions.
The use of flowmetry of the foetal renal artery offers a diagnostic improvement by analysing intrauterine centralisation of the foetal circulation. We used the examination results of 82 pregnant women, who were in intensive prenatal care, to check the prediction of foetal distress using the flowmetry of the renal artery. In foetuses showing an increased flow resistance of the aorta and a pathological flow of the renal artery, the rate of caesarian section, necessitated by foetal distress, was 63.6%. By the forming of quotients from the pulsatility indices of the internal carotid artery and the aorta on the one hand, and the renal artery and the internal carotid artery on the other hand, it seems to be possible to get information about the severity of the centralisation of the foetal circulation by existence of an intrauterine hypoxia. The rate of the operative delivery as a consequence of a foetal distress rises from 6.6% with normal PI quotients to 83.4% if both quotients are outside the double standard deviation.
The premature closure of the ductus arteriosus (pcDA) due to maternal tocolysis with indomethacin in the 34th week of gestation was diagnosed in a twin pregnancy. The pcDA was detected using Doppler 24 hours before both fetuses developed pleural effusion. Pathologic waveforms in the fetal aorta with end-diastolic zero-flow were registered. A no-delay caesarean section with optimal neonatologic intensive care were successful for the survival of the neonates. The authors postulate, that the amount of pcDA as a cause of NIHF is higher than generally supposed. Furthermore a tocolysis with indomethacin should not be performed after the 34th week of gestation.
Early detection of fetal malformations has become possible owing to the availability of highly advanced ultrasound systems. Majority of malformations, 30 per cent, has been recordable from urinary system. This system is early of access for the examiner, so that even sophisticated diagnosis of malformation is possible. High accuracy diagnosis has been increasingly helpful in forecasting pregnancy prognosis. Hence, with adequate perinatological management, it will be possible to influence on perinatal morbidity and mortality positively. 70 fetuses with malformations of kidneys and to urinary system have been observed in the context of this study. An assessment was made of diagnostic efficiency, postpartum development and long-range prognosis. Recommendations are derived from the above mentioned findings for perinatological approach in cases of diagnosed malformations of kidneys and the other urinary system.
The paper gives an overview of the application in obstetrics of Doppler-ultrasound for blood flow measurements. Both usual methods, the continuous-wave and the pulsed Doppler are compared, including the safety aspects of the investigation. The advantages and disadvantages of quantitative and qualitative analysis of the Doppler spectrum are discussed and the necessary terms as Pulse Repetition Frequency (PRF), High Pass Filter (HPF), sample volume, aliasing and Doppler spectrum explained. The vessels of interest and the clinical importance they reflect are demonstrated. The importance of this new non-invasive mean in the assessment of utero-feto-placental haemodynamics is underlined.
The measurement of fetal and maternal blood flow velocities by Doppler-ultrasound is the first noninvasive method of studying utero-feto-placental haemodynamics. The pulsed Doppler is used by many observers to diagnose variations in the tissue resistance in certain clinical situations. The Doppler-ultrasound get the main importance in cases of intrauterine growth retardation, pregnancy induced hypertension, pregnancies in combination with diabetes mellitus and in cases of intrauterine hypoxia. This paper gives an overview about the clinical range of Doppler-velocimetry-investigations.
Recent studies have shown that oestrogen can induce desensitization to its own gonadotrophin-inhibiting effect in female rats by an action on the medial preoptic area (MPOA). Probably as a consequence of this action, sensitivity to the negative oestrogen feedback declines markedly between metoestrus and dioestrus of the 4-day ovarian cycle. To study this desensitization process in 5-day cyclic rats, females exhibiting regular 5-day vaginal cyclicity were ovariectomized on consecutive days of the cycle, injected with oestradiol benzoate (OB) or oil on the day of ovariectomy and autopsied 24 h after the injection. Estimation of the serum concentration of LH revealed that desensitization to negative oestrogen feedback occurred only between day 2 of dioestrus and pro-oestrus, i.e. 2 days later than in females with a 4-day cycle. In the latter animals, an injection of progesterone in metoestrus or early dioestrus, which induced lengthening of the ovarian cycle for 1 day, delayed the onset of desensitization to a degree similar to that found in spontaneously 5-day cyclic rats. In acutely ovariectomized females, progesterone implants placed in the MPOA, but not those located in the mediobasal hypothalamus, increased the LH-inhibiting effect of low doses of OB. The results suggest that the prolonged secretion of progesterone recorded in 5-day cyclic rats retards follicle maturation and delays the forthcoming ovulation by acting, at least partly, on the MPOA and antagonizing the desensitizing effect of oestrogen. In this way, inhibition of gonadotrophin secretion by oestrogen is enhanced and the increase in tonic LH secretion necessary for the completion of follicle maturation is retarded.
It has recently been demonstrated in women and several mammalian species that the basal LH secretion increases prior to the ovulation-inducing LH surge in spite of a simultaneous rise of the estrogen level in the blood. The temporary relative inefficiency of estrogen in its negative feedback action may be necessary to make adequate gonadotrophic support of final preovulatory follicle maturation possible. To study the mechanisms underlying this phenomenon, the gonadotrophic response to a single injection of estradiol benzoate (EB) was evaluated in acutely ovariectomized adult rats during the different stages of a 4-day ovarian cycle. The results showed that the sensitivity to the gonadotrophin-inhibiting effect of EB is high during late estrus and early metestrus. Between metestrus and diestrus it suddenly declines, and EB did not inhibit the hypophysial gonadotrophin secretion from diestrus through the morning of the subsequent estrus. The cyclic variation of the sensitivity to the negative estrogen feedback is probably not based upon an endogenous rhythm that is independent of the ovarian hormone secretion, because similar variability of the gonadotrophic response to estrogen was not found in rats that had been castrated three days before the injection of EB. A further experiment demonstrated that bilateral implants of EB placed in the medial preoptic area (MPOA) of ovariectomized rats significantly reduced the gonadotrophin-inhibiting effect of s. c. injected estradiol, whereas similar implants located in the mediobasal hypothalamus were completely ineffective in this regard. Since bilateral lesioning of the MPOA in long-term ovariectomized females also lowered the sensitivity to estrogen, the conclusion may be drawn that preovulatory desensitization to the negative estrogen feedback is probably induced in cyclic female rats by an inhibitory effect on medial preoptic neurones of the increase of circulating estrogen recorded in metestrus. In accordance with this assumption, imitation of the periovulatory diminution of estrogen action on the MPOA of intact rats by the removal of medial preoptic EB implants in castrated females during the afternoon of proestrus, resulted in high sensitivity to estrogen during estrus and metestrus. The possible clinical significance of the hitherto not described preovulatory desensitization is briefly discussed.
Explore the source record for details and available documents.
Two cases of distal colonic obstruction due to endometriosis prompted the authors to elaborate on problems implied in diagnosis and therapy of this rare cause of ileus. Accurate preoperative diagnosis was usually not obtainable from case histories, endoscopy, and X-ray checks. Only emergency operations should be performed on ileus cases (colostomy, Hartmann's operation). Hormonal and surgical treatment should then be continued in consultation with the gynaecologist. Resections should be minimised and mutilating interventions (rectal amputation) avoided.
Unilateral implants containing oestradiol benzoate (OB) and cholesterol at the ratio of 1 + 4 were placed for 48 h either in the region of the anterior amygdaloid area (AAA) and nucleus of the lateral olfactory tract (NLOT) or in the anterior or posterior part of the mediocortical amygdala of immature 26-day-old female rats, and the age at vaginal opening and the first ovulation was recorded. Whereas implants located in the mediocortical amygdala did not influence the occurrence of ovulation or advanced it distinctively, implantation of OB into the AAA/NLOT resulted in a highly significant delay of the first pubertal ovulation that was associated with postpubertal persistent vaginal cornification in part of the rats.
To examine the question if an endogenous oestrogen-independent rhythm is involved in the cyclic variation of sensitivity to the negative feedback of oestrogen recorded in a former study, adult female rats were ovariectomized on subsequent days of a 4-day ovarian cycle, injected with 3 micrograms oestradiol benzoate (OB)/100 g b.w. or oil three days after castration, and autopsied on the following day. Estimation of the serum LH concentration revealed a similar LH-inhibiting effect of OB in all experimental groups. Female rats were then implanted with OB or cholesterol in the medial preoptic area (MPOA) in metoestrus. In part of the rats, the implants were removed on the presumptive day of pro-oestrus to imitate the periovulatory decline of the circulating oestrogen level acting on the MPOA. Evaluation of the sensitivity to the negative oestrogen feedback during oestrus and metoestrus demonstrated that s.c. injected OB was highly effective in suppressing the LH secretion after removal of the OB implants in pro-oestrus, but not in rats with the implants left in place till autopsy. In a final experiment, the pro-oestrous progesterone surge was inactivated by the injection of specific antibodies. An influence of this treatment on the LH-inhibiting effect of OB examined during oestrus and metoestrus could not be found. Taken together the results suggest that the high sensitivity to the negative oestrogen feedback recorded during the postovulatory period in cyclic female rats is mainly induced by the periovulatory fall of the circulating oestrogen level leading to reduction of the medial preoptic oestrogen concentration.
The gonadotrophic response to a single injection of oestradiol benzoate (OB) was studied in acutely ovariectomized adult rats during the different stages of a 4-day ovarian cycle. The results showed a sudden decline of the sensitivity to the gonadotrophin-inhibiting effect of OB between metoestrus and dioestrus. This desensitization to the negative oestrogen feedback was probably caused by an oestrogen action on the medial preoptic area (MPOA). In rats ovariectomized and implanted with OB in the MPOA in metoestrus, an s.c. injection of OB on the presumptive day of pro-oestrus did not lower the circulating LH and FSH levels, whereas a clear suppression of gonadotrophin secretion was seen in females implanted with cholesterol in the MPOA or implanted with OB in the hypothalamic ventromedial-arcuate region. Similar findings were obtained in rats which had been ovariectomized 3-4 weeks before implantation. A final experiment demonstrated that bilateral lesioning of the MPOA also reduced the sensitivity to the negative feedback action of oestrogen in long-term ovariectomized rats. In all experiments performed, diminution of the oestrogen-induced inhibition of LH secretion was more marked than that of suppression of FSH secretion. It is proposed that desensitization to the negative oestrogen feedback, probably resulting from an inhibitory oestrogen action on medial preoptic neurones, is a prerequisite for adequate gonadotrophic support of preovulatory follicle maturation in the presence of a continuously rising oestrogen concentration in the blood.