Doppler assessment of the placental circulation plays an important role in screening for impaired placentation and its complications of pre-eclampsia, intrauterine growth restriction and perinatal death. Assessment of the fetal circulation is essential in the better understanding of the pathophysiology of a wide range of pathological pregnancies and their clinical management. This book provides a comprehensive account of Doppler ultrasound in Obstetrics and will be of value to those involved in antenatal care and fetal medicine.The first chapter explains how the competent use of Doppler ultrasound techniques requires an understanding of the hemodynamics within vessels, the capabilities and limitations of Doppler ultrasound, and the different parameters which contribute to the flow display. Chapter 2 examines how ultrasound can cause thermal and mechanical effects in the body and emphasizes the responsibility of sonographers in ensuring that ultrasound is used safely. Chapter 3 describes the methodology for obtaining and analyzing flow velocity waveforms from the uterine and umbilical arteries and fetal heart, arteries and veins and explains the physiological changes that occur during pregnancy. Chapter 4 reviews the effects of impaired placental perfusion on fetal oxygenation and the hemodynamic responses to fetal hypoxemia. Chapter 5 summarizes the results of screening studies involving assessment of impedance to flow in the uterine arteries in identifying pregnancies at risk of the complications of impaired placentation, and examines the value of prophylactic treatment with low-dose aspirin, vitamins C and E and nitric oxide donors in reducing the risk for subsequent development of pre-eclampsia. The hemodynamic responses to fetal anemia and the value of Doppler ultrasound in the management of red cell isoimmunized pregnancies are described in Chapter 6. Chapter 7 outlines the relation between impedance to flow in the uterine and umbilical arteries and maternal glycemic control or maternal nephropathy and vasculopathy in diabetes mellitus. It also describes the hemodynamic consequences of fetal acidemia and hypertrophic cardiomyopathy. Chapter 8 discusses the potential value of Doppler ultrasound in the management of pregnancies with preterm prelabor amniorrhexis, both in terms of distinction between infected and non-infected cases and in the prediction of pulmonary hypoplasia. The value of uterine and umbilical artery Doppler in identifying pregnancies at risk of pre-eclampsia, intrauterine growth restriction and perinatal death in systemic lupus erythematosus and antiphospholipidsyndrome is summarized in Chapter 9. Chapter 10 reviews the Doppler findings in the placental and fetal circulations in post-term pregnancies and examines the value of Doppler in the prediction of perinatal death. Chapter 11 presents the Doppler findings in twin pregnancies and the hemodynamic changes associated with discordant fetal growth due to placental insufficiency and twin-to-twin transfusion syndrome. Chapter 12 and Chapter 13 describe the application of color Doppler in the diagnosis of cardiac and extracardiac abnormalities, respectively.As with the introduction of any new technology into routine clinical practice, it is essential that those undertaking Doppler assessment of the placental and fetal circulations are adequately trained and their results are subjected to rigorous audit. The Fetal Medicine Foundation, under the auspices of the International Society of Ultrasound in Obstetrics and Gynecology, has introduced a process of training and certification to help to establish high standards of scanning on an international basis. The Certificates of Competence in Doppler assessment of the placental and fetal circulations are awarded to those sonographers that can perform these scans to a high standard, can demonstrate a good knowledge of the indications and limitations of Doppler and can interpret the findings in both high-risk and low-risk pregnancies.
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