The DopFet system: a new ultrasonic Doppler system for monitoring and characterization of fetal movement.

To enable the investigation of fetal movement in a manner similar to fetal heart rate (FHR) monitoring we have developed an apparatus (the DopFet system) that consists of a pair of miniature sensors, a 2-MHz continuous-wave directional Doppler electronic module and a laptop personal computer. One of the sensors is aimed at the fetal limbs and the other at the thorax to detect heart and upper body movements. The signals are analyzed, presented in real-time and postprocessed by software developed by us. The postprocessing software computes a number of parameters (the DopFet parameters) describing fetal movement. These parameters can be divided into two categories: parameters that describe the quantity of fetal movement (i.e., number of movements) and parameters that describe qualitative aspects of fetal movement (i.e., average movement duration). Future studies using the DopFet system will be aimed at discovering which of these parameters or combination of parameters is the best indicator of fetal well-being. We present an example of a 0.5 h recording and the results of testing on 23 volunteer mothers. These results show good sensitivity of the system compared to real-time ultrasound (US). The system detects 96% of rolling movements, 100% of flexion movements and 97% of leg movements.

Distance of foetal movement measured using the analytical signal derived from non-directional Doppler sound.

Foetal heart rate (FHR) monitoring using the Doppler shift resulting from the movements of the foetal heart is a standard examination in most obstetrical wards. Other movements also give rise to a low frequency Doppler shift. These signals are incompletely understood. Their characteristics may offer a way for diagnostic exploitation through complementing or replacing time consuming ultrasound observation of foetal movements. It is shown that a wealth of information is contained in these signals which can easily be extracted on line by a standard PC computer using straightforward methods of signal processing. In its amplitude an ultrasonic Doppler signal contains information concerning the size of the reflector in movement and speed as frequency. The displacement of the reflector can also be derived from the phase evolution of a complex Doppler signal. Examples of signals generated by various types of foetal activity are shown and analyzed.

Feto-maternal circulation: mathematical model and comparison with Doppler measurements.

OBJECTIVES: Clinicians are more and more frequently studying fetal blood flow velocity curves recorded by Doppler ultrasound in vital organs such as the placenta and fetal brain to evaluate fetal well-being. We have therefore developed a mathematical model of the utero-placental and fetal circulations which could be used for teaching and for a better understanding of regulatory mechanisms. METHODS: The model is based on two basic elements-an arterial segment and a bifurcation-and we have reproduced the major arteries of the feto-maternal circulation combining these basic elements. The mathematical model of the system is based on the Navier-Stokes equations. The peripheral areas such as the brain, kidneys and placenta are modeled by a simple Windkessel model and the model computes instantaneous flow and pressure at any point in the fetal arterial tree and the uterine arteries. RESULTS: We have compared the computed instantaneous flow curves and pressure with in vivo data and our results agree with the findings in physiological situations and in gravidic hypertension. CONCLUSIONS: Our model provides new interesting insights into fetal hemodynamics such as a better understanding of the mismatch impedance phenomena and is a promising model for the study of blood redistribution mechanisms in hypoxic situations.

Etiology, prognosis and management of nuchal cystic hygroma: 25 new cases and literature review.

OBJECTIVE: To develop an algorithm for the prenatal management of patients when a cystic hygroma is diagnosed by ultrasonography. METHODS: We report a personal series of 25 cases diagnosed between 10 and 23 weeks gestation and a review of the literature comprising a total of 999 cases. We focused on the etiologies and the value of various prognostic factors in the management of cystic hygromas. These include karyotype, alpha-fetoprotein levels, sonographic findings in the fetus and within the hygroma itself, and natural history. RESULTS: According to the literature, fetal chromosomal abnormalities were associated with cystic hygromas in 62% of the cases. Turner's syndrome remains the most common (33%) but Down's syndrome, Trisomy 18 and Trisomy 13 are not rare (15, 7 and 2%). Others have Mendelian abnormalities. The prognosis remains gloomy. The literature reports that only 9% of cases result in healthy children with normal karyotypes. The remaining 91% are either terminated (89%) or liveborn (2%), but with chromosome abnormalities or various malformations. CONCLUSION: The prognostic factors associated with a poor outcome are an abnormal karyotype and associated structural malformations. Resolution of the hygroma by 20 weeks gestation suggests a good prognosis, but is not definitive. All other factors evaluated do not appear to be of prognostic value at this time. Careful analysis of these prognostic factors is very important to identify the small percentage of normal children and to advise parents effectively for a future pregnancy.

[In utero measurement of the umbilical cord in full term pregnancy]. / Mesure in utero de la longueur du cordon ombilical au cours de grossesses à terme.

OBJECTIVE: The length of the umbilical cord varies widely from one pregnancy to another. Although its average length is 50 cm, this measurement could vary from as little as 20 cm to more than one metre. The purpose of our study was to evaluate, in utero, the length of the umbilical cord during the third trimester of pregnancy knowing the propagation velocity of the pressure wave along the cord. MATERIAL AND METHODS: The computation of the apparent length requires two ultrasound transducers, one situated at the aortic fetal arch, the other at the placental extremity of the umbilical artery. Knowing the velocity of the pressure wave (v), as well as the time interval between the systolic peak of two waves (delta t), we can deduce the length of the umbilical cord (delta t x v). RESULTS: The comparison between the calculated length and the actual length measured shows a significant correlation with a probability of 1%. CONCLUSION: The knowledge of the length of the umbilical cord is quite useful in the physio-pathological interpretation of the placental resistance index. It is also of interest, before the delivery, to know the length of the cord in order to foresee dystocy and how it relates cord which is either too short or too long.

[Ethical problems raised by the current French practice of therapeutic abortions. Part I: prospective study for 24 months at the University Hospital of Tours (76 cases)]. / Problèmes éthiques soulevés par les pratiques françaises actuelles de l'interruption médicale de grossesse. 1re Partie: Etude prospective sur 24 mois au CHU de Tours (76 cas).

OBJECTIVE: Determine the circumstances and conditions concerning ethical problems raised by medical abortions treated in a University hospital. METHODS: Prospective study for 2 years (1 Sept 1991--31 Aug 1993) conducted with a consulting Committee for the antenatal diagnosis and fetal medicine at the University Hospital at Tours. Each discussion of the medical file for proposed medical abortions, the conditions leading to the decision and the ethical recommendations formulated were registered as well as the outcome of the pregnancy and for the infant. RESULTS: There were 76 cases raising ethical problems. They were divided into 3 categories of recommendations: medical abortion (55 cases), abstention with acceptation of possible fetal death in utero (11 cases), conservation of the pregnancy (10 cases). CONCLUSION: A practical attitude could usually be decided after discussion between parents and physicians. A few cases of disagreement were observed which led to uncertainty [correction of incertainty] and diverging opinions concerning the diagnosis and prognosis for the fetal pathology.

The use of perioperative Doppler ultrasound as a screening test for acute tubular necrosis.

For many years Doppler ultrasound has helped to identify the cause of renal allograft dysfunction. However, Doppler examinations were often performed after the onset of acute renal failure. In the present study we used Doppler ultrasound during grafting to follow changes in renovascular resistance. As early as 30 min after the renal artery had been unclamped, the calculated resistance index (RI) at the hilar part of the renal artery was significantly higher in the group of patients who developed acute tubular necrosis (ATN) than in the group of patients with early normalization of renal function (P = 0.05). This result did not correlate with raised cold and warm ischemia times and serum creatinine level on discharge in patients who presented with ATN. RI higher than 0.730 min after unclamping allows for an identification of those grafts at greater risk for the development of ATN and should be an indication for the early introduction of intensive therapy.

[Modeling of feto-placental circulation. Clinical applications apropos of 21 patients having no or inverse diastolic umbilical flow]. / Modélisation de la circulation foeto-placentaire. Applications cliniques à propos de 21 patientes ayant un flux ombilical diastolique nul ou inversé.

The placental resistance index: (S-D)/S (S: represents the amplitude of the systolic peak and D: the amplitude of the telediastolic peak) is constantly inferior to one from the 14th-16th week of amenorrhea during a normal pregnancy. The diastolic umbilical arterial blood flow is continuous because of low placental vascular resistance. From a clinical study of 21 patients with an absent or reversed end diastolic flow in umbilical artery waveforms, an obliterative process in the placental vascular tree was observed. A computer model was used to stimulate the reversed end diastolic flow in umbilical artery waveforms when the placental resistance increased. This haemodynamic approach shows that the placental blood flow decreased, and that the arterial blood pressure, as well as the pulse wave velocity increased when the placental resistance increased. The increase in the difference between the umbilical resistance and the placental resistance caused a reduction of the diastolic flow owing to a progressive increase of the pulse wave velocity reflected. It was concluded that there is a relation between perturbations in placental vascular bed and the flow in umbilical artery waveforms.

[Cerebral lesions observed in a twin after the in utero death of the other twin. Fetal anoxia-ischemia can be the possible mechanism (3 cases)]. / Lésions cérébrales observées chez un jumeau après mort in utero de l'autre jumeau. Une anoxie-ischémie foetale peut être le mécanisme causal (3 observations).

BACKGROUND: The death of one twin in utero may result in visceral lesions, of possible vascular origin, in the surviving twin when the pregnancy is monochorionic and diamniotic. CASES REPORT: Case n. 1: The death of one twin and enlargement of the ventricular system in the other were seen by ultrasonography at 24 weeks of pregnancy, 8 weeks after the mother had a fall on the stairs. The heterogeneous imaging in the inferior part of placenta suggested a clot in this area. The pregnancy was terminated at 28 weeks because the ventricular dilatation continued to increase. The newborn died a few minutes later and examination of the placenta showed that the pregnancy was monochorionic and monoamniotic. Case n. 2: The death of one twin with macerating features was seen by ultrasonography at 31 weeks. The other twin was born at 32 weeks of a dichorionic, diamniotic pregnancy. Injection of milk into the placental vasculature failed to visualize any vascular anastomoses between the two placentas, but ultrasonography showed bilateral cystic lesions in the frontal lobes of the brain. Case n. 3: Acute polyhydramnios developed at 21 weeks of pregnancy; it was treated by 3 amniocenteses, while ultrasonography of the twins was normal. A fetal transfusion syndrome was observed at birth, the pregnancy being monochorionic and diamniotic. Cranial ultrasound on day 6 was normal in the recipient twin, but showed numerous cerebral cavities in the donor, which was confirmed at autopsy after that this twin suddenly died at 2 months of age. CONCLUSIONS: Brain lesions of vascular origin, can be observed in any type of twin pregnancies. They may be the result of transfusion of clot or thromboplastin-rich blood from the donor fetus through vascular anastomoses in a monochorionic placenta. They also may be due to anoxo-ischemic lesions in the absence of such anastomoses, or, in the fetal transfusion syndrome, to circulatory difficulties in one of the twins, as observed in premature singletons. In the cas of anoxo-ischemic lesions, anticipating the birth of the surviving twin is not justified.

Influence of the measurement location on the resistance index in the umbilical arteries: a hemodynamic approach.

A computer model was used to study the primary factors generating the reduction in resistance index, (S-D)/S, values observed by ultrasonic Doppler measurements in the umbilical artery, from the fetal insertion to the placental insertion (S represents the amplitude of the systolic peak and D the amplitude of the diastolic peak). This hemodynamic approach shows that the placental resistance is the primary factor, the viscosity and the cord length playing secondary roles. Clinically, the position of the measurement along the cord is an important factor. To increase the sensitivity of the index, the Doppler measurement must be performed near the fetal insertion, whereas a measurement near the placental insertion will make the Doppler examination more specific.

[Value of ultrasonic diagnosis of fetal malformations in the detection of chromosomal abnormalities]. / Intérêt du diagnostic échographique des malformations foetales dans le dépistage des anomalies chromosomiques.

We report 118 foetal karyotypes studied on the basis of ultrasonographic warning signs which appeared in pregnancies with no significant risk of chromosomal abnormalities, judging from the personal and familial histories. Foetal karyotyping was performed either in amniotic fluid (AF) or in foetal blood. The ultrasonographic warning signs fell into 3 categories: (1) intrauterine growth retardation (IUGR) which was harmonious and below the 5th percentile, without foetal malformation at ultrasonography and without maternal cause (doppler examination, normal Pourcelot's index): 30 cases (24.4%). IUGR was isolated in 22 cases and associated in 8 cases with abnormal amounts of amniotic fluid: oligoamnios 6, hydramnios 2; (2) Isolated abnormality of AF volume: 22 cases (18.8%); hydramnios 19 and oligoamnios 3; (3) Foetal malformations in 66 cases (56%), including 16 central nervous system malformations, 4 cystic hygromas, 10 urinary tract malformations, 9 foetal effusions, 9 abdominal wall abnormalities, 7 gastrointestinal malformations, 5 malformations of the limb and 3 cardiac malformations. The mothers' mean age was 27.5 +/- 4.5 years; the mean term of pregnancy at the time of foetal karyotyping was 28 +/- 6.5 AW. In 51% of the cases the ultrasonographic warning sign was discovered after 29 AW. Among the 118 foetal karyotypes studied, 12 chromosomal abnormalities (10.6%) were detected. During the same period, 712 foetal karyotypes were studied in women aged 38 or more and 18 chromosomal abnormalities (2.53%) were detected. This study confirms that more chromosomal abnormalities can be detected by ultrasonographic warning signs than by relying on the mother's age which is the most frequent reason for foetal karyotype studies. Ultrasonography performed during the second trimester of pregnancy is of value to evaluate foetal growth and the amount of AF and to investigate for possible foetal malformations.

[The contribution of color-coded Doppler in early vascular complications of kidney transplantation]. / Apport du Doppler à codage couleur dans les complications vasculaires précoces de la transplantation rénale.

Ultrasound techniques and radionuclide studies are very often used to assess vascularization of renal transplants. Although, in acute tubular necrosis or acute rejection, it is difficult to choose between these two techniques, in 3 recent cases of renal artery thrombosis, we conclude that color coded Doppler is preferable to nuclear medicine or duplex system to diagnose this form of thrombosis.

[Doppler examination of the umbilical arteries. Its role in the surveillance of pregnancy]. / L'examen Doppler des artères ombilicales. Sa place dans la surveillance de la grossesse.

Pregnancies with a high risk of fetal growth retardation are at present watched by using clinical observations and biological parameters including ultrasound and estimation of the fetal heart rate. The Doppler waveform in the umbilical arteries provides information about circulatory resistance in the placenta. An index of resistance "R" is evaluated on the Doppler trace. The purpose of this study is to describe the score (with its possibilities and limitations) for this parameter "R" to follow-up pregnancies with fetal growth retardation and to compare it with ultrasound, biological and clinical parameters that are commonly used. Two groups of pregnancies have been explored: pregnancies with hypertension and pregnancies with idiopathic fetal growth retardation. Abnormal values of "R" correlate well with failure of fetal growth. Furthermore pathological values of "R" do not correspond to the same population as abnormal values of the other parameters. In some cases "R" is disturbed before the others are. In conclusion, this study shows that the index increases the accuracy of detection and the follow-up of chronic fetal growth retardation, particularly in cases of pregnancies with vascular placental pathology.

[Tentative classification of the ultrasound symptomatology of the prostate by an anatomo-ultrasonic comparison of 34 cases]. / Tentative de classification de la sémiologie échographique de la prostate par confrontation anatomo-ultrasonique de trente-quatre cas.

Ultrasound and histological sections were taken of 34 prostate units removed from fresh cadavers. Ultrasonography seems to raise more problems than it solves; only 73% of the normal prostates were homogeneous under ultrasound. Ultrasonography visualized nodular structures requiring biopsy in 71% of the cases of prostatic adenoma. There were too few cases of malignant tumors in the sample to warrant a conclusion. They were highly evolved. Ultrasonography gave strong grounds for suspicion, but they could be easily diagnosed clinically.

[Ultrasound in the study of fetoplacental circulation]. / Les ultrasons dans l'exploration de la circulation foeto-placentaire.

Exploration of fetal vessels is performed with a duplex system which combines a real-time linear imaging system 3.5 MHz and a pulsed Doppler (2.5 MHz). The transducers of the imaging and Doppler systems are associated in the same probe. Umbilical and aortic circulation have been investigated on 100 pregnancies. The umbilical artery Doppler spectrum shows an important diastolic flow which increases all along the pregnancy. A decrease of this flow occurs when the placental circulatory resistances increase. In case of severe hypertension one can note a decrease or the disappearance of the diastolic flow related to the existence of vascular placental defects (infarctus). This was observed in pathological pregnancies with hypotrophy or fetal death. The placental resistances can be quantified with the Pourcelot index R = A - D divided by A, where A is the maximum systolic amplitude and D the maximum end diastolic amplitude, both measured on the umbilical artery spectrum. Fetal blood flow measurements were performed with the same device. The mean value of the blood flow is about 170 ml/min/kg in the aorta and 120 ml/min/kg in the umbilical arteries at the end of the pregnancy. The possibility to record simultaneously fetal aorta and inferior vena cava enable us to detect abnormal heart rate such as the atrioventricular block.