New insights into human functional ultrasound imaging

Ultrasound imaging is a vital tool for exploring in vivo the placental function which is essential to understand pathological phenomena such as preeclampsia or intrauterine growth restriction. As technology advances including ready availability of three-dimensional (3D) probes and novel software, new markers of placental function become possible. The objective of this review was to provide an overview of the new ultrasound markers of placental function with a focus on the potential clinical application of three-dimensional power Doppler (3DPD). A broad-free text literature search was undertaken based on human placental studies and sixty full-text studies were included in this review. Three-dimensional power Doppler is a promising technique to predict preeclampsia in the first trimester. However, the influence of external factors such as body mass index, parameter standardisation and machine settings still need to be addressed. Contrast-enhanced ultrasound is currently reserved for research, because the required injected contrast mediums are not currently approved for use in pregnancy, although the safety data is reassuring.

The Impact of Technology on the Diagnosis of Congenital Malformations

As technology improves and becomes more widely accessible, more subclinical congenital malformations are being detected. Using a cohort of 1,780,156 pregnant women and their offspring nested in the 2000-2013 US Medicaid Analytic eXtract, we contrasted time trends in malformations which do not necessarily present with overt clinical symptoms early in life and are more likely to be diagnosed via imaging (secundum atrial septal defect, patent ductus arteriosus, ventricular septal defect, pulmonary artery anomalies, pulmonary valve stenosis, hydrocephalus) with trends in malformations that are unlikely to escape clinical diagnosis (tetralogy of Fallot, coarctation of the aorta, transposition of the great vessels, hypoplastic left heart syndrome, oral cleft, abdominal wall defect). Logistic regression was used to account for trends in risk factors while assessing the impact of increased screening intensity. Prevalence of the diagnosis of secundum atrial septal defect rose from 2.3‰ in 2000-2001 to 7.5‰ in 2012-2013, of patent ductus arteriosus from 1.9‰ to 4.1‰, and of ventricular septal defect from 3.6‰ to 4.5‰. Trends were not explained by changes in the prevalence of risk factors but were attenuated when accounting for screening tests. The other malformations showed no temporal trends. Findings suggest that increased screening partially explains the observed increase in diagnosis of milder cases of select common malformations.

[Prenatal first trimester fetal diagnosis in Sweden today and in the future]

Prenatal first trimester fetal diagnosis in Sweden today and in the future The combined first trimester test for detection of trisomy 21 has been available in Sweden the last 10 years but the uptake among pregnant women is still less than 50% and varies largely between different regions. The non-invasive prenatal test (NIPT) has been introduced and is currently recommended to be used as a secondary test only in those women who have an increased risk following the combined test. With falling costs for NIPT and a general offer of this test as a primary screening tool to all women there is concern that the first trimester ultrasound scan will be abandoned. There are however many arguments for retaining the scan and use this examination to clarify unclear NIPT results, detect major structural malformations, date pregnancies, determine chorionicity in twins and predict and treat preeclampsia already in the first trimester.

Ultrasound in Africa: what can really be done?

Today we are living in a globalized world in which information on what is happening in one part of the world is easily communicated to other parts of the world. This happens thanks to advancement in science and technology. One area where technology has made the greatest impact is heath care provision. Ultrasound technology is now playing a critical role in health care provision particularly in Obstetrics and Gynaecology. This has significantly assisted in provision of quality health care to pregnant women and their unborn infants and in reducing maternal and neonatal morbidity and mortality in the developed world. Africa the continent with greatest health care challenges and with the highest maternal and neonatal mortalities is yet to fully utilize this important technology. The need for this technology is great as the conditions requiring its application abound. The effective application of Ultrasound however faces serious challenges in Africa. To successfully entrench Ultrasound in quality Obstetrics and Gynaecology care various approaches must be adopted to overcome the challenges. The aim of this paper is to identify the benefits and the challenges inimical to the application Ultrasound in Obstetrics and Gynecology in Africa. It also examines what needs to be done to achieve better application of Ultrasound in Obstetrics and Gynecology.

The Fetal Modified Myocardial Performance Index: Is Automation the Future?

The fetal modified myocardial performance index (Mod-MPI) is a noninvasive, pulsed-wave Doppler-derived measure of global myocardial function. This review assesses the progress in technical refinements of its measurement and the potential for automation to be the crucial next step. The Mod-MPI is a ratio of isovolumetric to ejection time cardiac time intervals, and the potential for the left ventricular Mod-MPI as a tool to clinically assess fetal cardiac function is well-established. However, there are wide variations in published reference ranges, as (1) a standardised method of selecting cardiac time intervals used in Mod-MPI calculation has not been established; (2) cardiac time interval measurement currently requires manual, inherently subjective placement of callipers on Doppler ultrasound waveforms; and (3) ultrasound machine settings and ultrasound system type have been found to affect Mod-MPI measurement. Collectively these factors create potential for significant inter- and intraobserver measurement variability. Automated measurement of the Mod-MPI may be the next key development which propels the Mod-MPI into routine clinical use. A novel automated system of Mod-MPI measurement is briefly presented and its implications for the future of the Mod-MPI in fetal cardiology are discussed.

Prenatal diagnosis of transposition of the great arteries over a 20-year period: improved but imperfect

OBJECTIVE

To evaluate temporal trends in the prenatal diagnosis of transposition of the great arteries with intact ventricular septum (TGA/IVS) and its impact on neonatal morbidity and mortality.

METHODS

We included in this study cohort newborns with TGA/IVS who were referred for surgical management to our center over a 20-year period (1992-2011). The study period was divided into five 4-year periods and the primary outcome was rate of prenatal diagnosis. Secondary outcomes included neonatal preoperative status and perioperative survival.

RESULTS

Of the 340 patients with TGA/IVS, 81 (23.8%) had a prenatal diagnosis. The rate of prenatal diagnosis increased over the study period, from 6% in 1992-1995 to 41% in 2008-2011 (P < 0.001). Compared to patients with a postnatal diagnosis, balloon atrial septostomy (BAS) was performed earlier in patients with a prenatal diagnosis (0 days after delivery vs 1 day after delivery, respectively; P < 0.001) and fewer prenatally diagnosed neonates required mechanical ventilation (55.6% vs 68.0%; P = 0.03). Between patients with a prenatal or postnatal diagnosis of TGA/IVS, there were no statistically significant differences in the incidence of preoperative acidosis (16.0% vs 25.5%; P = 0.1), need for preoperative extracorporeal membrane oxygenation (2.5% vs 2.7%; P = 1.0) or mortality (one preoperative and no postoperative deaths among prenatally diagnosed patients compared with four preoperative and six postoperative deaths among postnatally diagnosed patients).

CONCLUSIONS

The prenatal detection rate of TGA/IVS has improved but still remains below 50%, suggesting the need for strategies to increase detection rates. The mortality rate was not statistically significantly different between prenatally and postnatally diagnosed patients, however, there were significant preoperative differences with regard to earlier BAS and fewer neonates that required mechanical ventilation. Ongoing work is required to ascertain whether prenatal diagnosis confers long-term benefits.

Past and present in omphalocele treatment in Romania

BACKGROUND

Omphalocele is a congenital abnormality whose prognosis has improved significantly over the last few decades, reaching a survival rate of 80-90% in developed countries. Currently, in Romania no comprehensive study on the incidence, treatment, and survival of patients with this defect of the anterior abdominal wall has been carried out.

METHODS

This retrospective analytical study was conducted over a period of 23 years and included 105 children with omphalocele. Prenatal diagnosis, referral to our hospital, children age upon admission, associated diseases, medical and surgical management, early and late postoperative complications, and the length of hospital stay were analysed.

RESULTS

The low rate of antenatal diagnosis (13.3%), the high frequency of associated congenital malformations (71.4%) and chromosomal abnormalities (27.6%), inadequate and delayed transport to a specialized pediatric surgery center together with an increased rate of sepsis (37.1%)resulted in a high mortality rate (54.3%).

CONCLUSIONS

The significantly reduced length of hospital stay and higher survival rate despite the apparently more frequent medical complications plead for the surgical treatment of omphalocele whenever not contraindicated by the presence of severe pulmonary hypoplasia, cardiac defects, immaturity and other severe congenital anomalies, when conservative treatment is indicated.

Recent advances in sonographic imaging of fetal thoracic structures

Recent ultrasonographic methods applied in the evaluation of fetal thoracic structures and anomalies are presented. Fetal lung volumetric assessment by 3D ultrasonography, analysis of the thoracic wall by 3D-rendered image and 3D skeletal-mode imaging, intrathoracic vessel evaluation by 3D power Doppler ultrasonography, analysis of heart anatomy and abnormalities by 4D spatiotemporal image correlation, identification of normal and abnormal intrathoracic almost isoechogenic structures by volume contrast imaging and evaluation of the heart and great vessels by 3 and 4D inverse mode will be reviewed.

Color Doppler sonography in obstetrics and gynecology

This review aims to provide the reader with an overview of the present and future clinical applications in color Doppler sonography for the evaluation of vascularity and blood flow within the uterus (both gravid and nongravid), ovaries, fetus and placenta. The clinical use of color Doppler sonography has been demonstrated within many organ systems. Color Doppler sonography has become an integral part of cardiovascular imaging. Significant improvements have recently occurred, improving the visualization and evaluation of intra-organ vascularity, resulting from enhancements in delineation of tissue detail through electronic compounding and harmonics, as well as enhancements in signal processing of frequency- and/or amplitude-based color Doppler sonography. Spatial representation of vascularity can be improved by utilizing 3D and 4D (live 3D) processing. Greater sensitivity of color Doppler sonography to macro- and microvascular flow has provided improved anatomic and physiologic assessment throughout pregnancy and for pelvic organs. The potential use of contrast enhancement is also mentioned as a means to further differentiate benign from malignant ovarian lesions. The rapid development of these new sonographic techniques will continue to enlarge the scope of clinical applications in a variety of obstetric and gynecologic disorders.

Normative data for fetal cisterna magna length measurement between 18 and 24 weeks of pregnancy

PURPOSE

The aim of this study was to determine normative data for fetal cisterna magna length (CML) measurement in a Brazilian population.

METHODS

This was a retrospective cross-sectional study on 3,862 normal singleton pregnancies between the 18th and 24th weeks of pregnancy. Fetal CML was measured in the axial plane of the fetal head, at lateral ventricle level, including the cavum septum pellucidum, thalamus, third ventricle, and transverse cerebellar diameter. The anteroposterior measurement was made between the posterior border of the cerebellar vermis and the internal face of the occipital bone. To assess the correlation between CML and gestational age (GA), polynomial equations were calculated, with adjustments using determination coefficient (R2).

RESULTS

The mean CML ranged from 4.29±0.93 mm at 18 to 18+6 weeks to 5.58±1.23 mm at 24 to 24+6 weeks of pregnancy. There was a good correlation between CML and GA, best represented by a linear equation: CML=0.535+0.208*GA (R2=0.084).

CONCLUSION

We established normative data for fetal CML in the second trimester of pregnancy, in a large Brazilian population.

Trends in diagnostic ultrasound acoustic output from data reported to the US Food and Drug Administration for device indications that include fetal applications

OBJECTIVES

A survey was conducted of acoustic output data received by the US Food and Drug Administration for diagnostic ultrasound devices whose indications for use include fetal applications to assess trends in maximum available acoustic output over time.

METHODS

Data were collected from 124 regulatory submissions received between 1984 and 2010. Data collection excluded transducers not indicated for diagnostic fetal imaging. The output parameters of ultrasonic power, mean center frequency, and bone thermal index (TIB) were extracted or computed from the submissions for 3 periods: 1984-1989, 1992-1997, and 2005-2010. The data were stratified according to the following imaging modes: M-mode, B/M-mode, pulsed wave Doppler, color flow Doppler, and continuous wave Doppler.

RESULTS

Ultrasonic power and maximum TIB values have increased roughly an order of magnitude from pre-1991 to post-1991 periods; the center frequency has decreased somewhat (4.2 to 3.4 MHz). The percentage of Doppler-mode transducers has increased substantially over time, with the majority of the diagnostic fetal imaging transducers currently designed to operate in Doppler modes; this increase is particularly important, since Doppler modes generate much higher TIB levels than B/M-modes. Color flow Doppler ultrasound currently operates at the highest mean ultrasonic power level (with a 14-fold increase over time).

CONCLUSIONS

The observed trends in increased acoustic output for both Doppler and non-Doppler modes underscore the widely recognized importance of adherence to the ALARA (as low as reasonably achievable) principle and prudent use in fetal ultrasound imaging.

The fetal three-vessel and tracheal view revisited

The routine use of four-chamber screening of the fetal heart was pioneered in the early 1980s and has been shown to detect reliably mainly univentricular hearts in the fetus. Many conotruncal anomalies and ductal-dependent lesions may, however, not be detected with the four-chamber view alone and additional planes are needed. The three-vessel and tracheal (3VT) view is a transverse plane in the upper mediastinum demonstrating simultaneously the course and the connection of both the aortic and ductal arches, their relationship to the trachea and the visualization of the superior vena cava. The purpose of the article is to review the two-dimensional anatomy of this plane and the contribution of colour Doppler and to present a checklist to be achieved on screening ultrasound. Typical suspicions include the detection of abnormal vessel number, abnormal vessel size, abnormal course and alignment and abnormal colour Doppler pattern. Anomalies such as pulmonary and aortic stenosis and atresia, aortic coarctation, interrupted arch, tetralogy of Fallot, common arterial trunk, transposition of the great arteries, right aortic arch, double aortic arch, aberrant right subclavian artery, left superior vena cava are some of the anomalies showing an abnormal 3VT image. Recent studies on the comprehensive evaluation of the 3VT view and adjacent planes have shown the potential of visualizing the thymus and the left brachiocephalic vein during fetal echocardiography and in detecting additional rare conditions. National and international societies are increasingly recommending the use of this plane during routine ultrasound in order to improve prenatal detection rates of critical cardiac defects.

Prenatal diagnosis of fetal congenital cystic adenomatoid malformation of the lung using three-dimensional ultrasound: comparison between the 20th and 21st centuries

OBJECTIVE

Congenital cystic adenomatoid malformation of the lung (CCAML) is one of the most common lung lesions diagnosed prenatally. In order to compare the trends and improvements of prenatal diagnosis of CCAML, we herein retrospectively reviewed our cases of fetal CCAML detected by three-dimensional ultrasound (3-D US) between two centuries.

MATERIALS AND METHODS

We reviewed our computer database of prenatal diagnosis of CCAML in National Cheng Kung University Hospital from October 1994 to November 2011. All of the fetuses were initially scanned by two-dimensional (2-D) US to locate the region-of-interest (ROI). Then, the 3-D probe was used to scan all of the ROI systematically and mechanically, and the images were stored in the laser discs for further 3-D visualization and reconstruction. To compare the characteristics at prenatal diagnosis of CCAML between the 20th and 21st centuries in our hospital, Chi-square tests were undertaken. A p value <0.05 was considered as statistically significant.

RESULTS

In total, 58 fetuses with CCAML were depicted by 3-D US in utero (12 cases were diagnosed in the 20th century and 46 cases in the 21st century). The ranges of gestational age at prenatal diagnosis of CCAML by 3-D US in the 20th century were between 15 and 36 weeks (mean=24 weeks), and were between 16 and 31 weeks (mean=22 weeks) in the 21st century. Moreover, nine cases (75%) were diagnosed at the second trimester in the 20th century, whereas 44 cases (96%) were diagnosed at the second trimester in the 21st century.

CONCLUSION

The advancement of 3-D US has remarkable advantages in adding novel visual depiction of a 3-D lesion of a 3-D fetus in 3-D US after reconstruction, and thus assists substantially in the prenatal diagnosis and genetic consultation of CCAML. Furthermore, the trend analysis in this series showed a significantly earlier gestational age at prenatal diagnosis of CCAML in the 21st century than that in the 20th century.

Narrowed beam width in newer ultrasound machines shortens measurements in the lateral direction: fetal measurement charts may be obsolete

OBJECTIVES

Fetal ultrasound measurements are made in axial, lateral and oblique directions. Lateral resolution is influenced by the beam width of the ultrasound system. To improve lateral resolution and image quality, the beam width has been made narrower; consequently, measurements in the lateral direction are affected and apparently made shorter, approaching the true length. The aims of this study were to explore our database to reveal time-dependent shortening of ultrasound measurements made in the lateral direction, and to assess the extent of beam-width changes by comparing beam-width measurements made on old and new ultrasound machines.

METHODS

A total of 41,941 femur length measurements, collected during the time-period 1987-2005, were analyzed, with time as a covariate. Using three ultrasound machines from the 1990s and three newer machines from 2007, we performed 25 series of blinded beam-width measurements on a tissue-mimicking phantom, measuring at depths of 3-8 cm with a 5-MHz transducer.

RESULTS

Regression analysis showed time to be a significant covariate. At the same gestational age, femur length measurement was 1.15 (95% CI, 1.08-1.23) mm shorter in the time-period 1999-2005 than in the time-period 1987-1992. Overall, the beam width was 1.08 (95% CI, 0.50-1.65) mm narrower with the new machines than with the old machines.

CONCLUSIONS

Technical improvements in modern ultrasound machines that have reduced the beam width affect fetal measurements in the lateral direction. This has clinical implications and new measurement charts are needed.

[First trimester ultrasound screening for fetal anomalies--classics and novelties]

The aim of this paper is to provide an up-to-date review of the possibilities for ultrasound screening for chromosomal and structural fetal anomalies in the first trimester. The major ultrasound and biochemical markers used in the assessment of risk for fetal abnormalities between 11+0-13+6 w.g. are described. The role of the first trimester fetal morphology scan in the in the echographic follow up of the pregnancy is discussed.

Doppler ultrasound in canine pregnancy

OBJECTIVE

The aim of this article is to review the current knowledge of Doppler ultrasound in canine pregnancy. A brief introduction of Doppler principles and their applications in human obstetrics is also included.

METHODS

A review of the peer-reviewed published literature was conducted of the articles pertaining to the use of Doppler ultrasound in canine pregnancy, general Doppler principles, and Doppler applications in human obstetrics.

RESULTS

In bitches, Doppler ultrasound has been used to assess ovarian, uterine, umbilical, fetal aorta, common carotid artery, and fetal caudal vena cava blood flow during normal gestation. Most of these vessels increase their blood flow during normal pregnancy. The resistive index and systolic/diastolic ratio of the uterine arteries have been recently described in an experimental pharmacologically induced model of abnormal canine gestation. Both indices progressively increase up to abortion, probably because of progesterone deprivation. Moreover, resistive index abnormalities have been found in canine cases of spontaneous abnormal gestations as described in human medicine.

CONCLUSIONS

Doppler ultrasound is a useful method for assessing development of the placental and fetal circulation during normal and abnormal canine pregnancy. Further studies are still necessary to widely use this technique in clinical practice.

Use of the genetic sonogram in the United States in 2001 and 2007

OBJECTIVE

The purpose of this study was to determine whether there have been changes in the use of second-trimester genetic sonograms and in the second-trimester sonographic markers used to screen for fetal aneuploidy by maternal-fetal medicine specialists in the United States from 2001 to 2007.

METHODS

A survey was mailed to Society for Maternal-Fetal Medicine members in the United States in April 2007 inquiring about their practice patterns regarding the genetic sonogram. Specific sonographic markers used for risk adjustment as part of the genetic sonogram were also assessed. The responses from 2007 were compared with responses from a similar survey administered in 2001 (Am J Obstet Gynecol 2002; 187:1230-1234) using descriptive statistics, the chi(2) test, and the Wilcoxon rank sum test.

RESULTS

A total of 991 responses were analyzed: 543 of 1638 (32%) in 2001 and 448 of 1756 (26%) in 2007. Significant increases (P < .0001) were noted in the number of specialists who used the genetic sonogram as a screening tool for Down syndrome and for every single sonographic marker used to adjust a woman's risk for having a fetus with Down syndrome during a genetic sonogram, except for choroid plexus cyst, clinodactyly, sandal gap toes, and widened pelvic angle.

CONCLUSIONS

Practitioners in the United States are using an increasing number of second-trimester sonographic markers to help identify aneuploid fetuses. The growing acceptance of sonography to screen for fetal aneuploidy and the recommendation by the American College of Obstetricians and Gynecologists for universal screening suggest that more resources may be necessary to meet the growing demand for second-trimester sonograms.

Safety assurance in obstetrical ultrasound

Safety assurance for diagnostic ultrasound in obstetrics began with a tacit assumption of safety allowed by a federal law enacted in 1976 for then-existing medical ultrasound equipment. The implementation of the 510(k) pre-market-approval process for diagnostic ultrasound resulted in the establishment of guideline upper limits for several examination categories in 1985. The obstetrical category has undergone substantial evolution from initial limits (ie, 46 mW/cm2 spatial peak temporal average [SPTA] intensity) set in 1985. Thermal and mechanical exposure indices, which are displayed onscreen according to an Output Display Standard, were developed for safety assurance with relaxed upper limits. In 1992, with the adoption of the Output Display Standard, the allowable output for obstetrical ultrasound was increased in terms of both the average exposure (eg, to a possible 720 mW/cm2 SPTA intensity) and the peak exposure (via the Mechanical Index). There has been little or no subsequent research with the modern obstetrical ultrasound machines to systematically assess potential risks to the fetus using either relevant animal models of obstetrical exposure or human epidemiology studies. The assurance of safety for obstetrical ultrasound therefore is supported by three ongoing means: (1) review of a substantial but uncoordinated bioeffect research literature; (2) the theoretical evaluation of diagnostic ultrasound exposure in terms of thermal and nonthermal mechanisms for bioeffects; and (3) the skill and knowledge of professional sonographers. At this time, there is no specific reason to suspect that there is any significant health risk to the fetus or mother from exposure to diagnostic ultrasound in obstetrics. This assurance of safety supports the prudent use of diagnostic ultrasound in obstetrics by trained professionals for any medically indicated examination.

Life and death before birth: 4D ultrasound and the shifting frontiers of the abortion debate

The development of 4D ultrasound technology has democratised fetal imagery by offering direct visual access to realistic images of the fetus in utero. These images, which purport to show a responsive being capable of complex behaviour, have renewed debate about the personhood of the fetus and the adequacy of current abortion regulation. This article considers recent abortion law reform initiatives in the United Kingdom and the United States and observes two shifts in the frontiers of these debates. The first concerns a shift from viability to sentience as a criterion of legal significance. The second concerns a shift toward constructing abortion in terms of feticide as distinct from the termination of pregnancy. Both strategies seek to deploy morphological similarities between the sentient fetus and newborn baby as a basis for extending law's dominion over the fetus.

Visual function at 11 years of age in preterm-born children with and without fetal brain sparing

OBJECTIVE

We have demonstrated earlier an accelerated maturation of the visual evoked potential in the first year of life in preterm infants with antenatal brain sparing. We have now assessed visual functioning at 11 years of age in the same cohort and compared the groups with and without brain sparing.

DESIGN/METHODS

One hundred sixteen survivors included in a study on the outcome of preterm infants born at <33 weeks' gestation with and without fetal brain sparing and admitted to the NICU were followed extensively. Ninety-eight infants (85%) were again assessed at 11 years of age. Data were available for fetal Doppler measurements indicating brain sparing, neonatal cerebral ultrasound scanning, and developmental outcome in the first 5 years. Mean birth weight was 1303 g; mean gestational age was 29.8 weeks. The infants were divided into 2 groups with and without brain sparing. Visual functioning was estimated by measuring visual acuity, visual fields, eye position, and binocular function and by visual motor tests.

RESULTS

Six percent of the children were found to have a visual acuity of <0.8, 12% had strabismus, and 14% to 46% showed abnormal results on the visual motor tests. No statistical differences were found between the 2 groups. However, children with severe cerebral ultrasound diagnoses in the neonatal period were found to have significantly more abnormalities on visual functioning and lower scores on visual motor tests than children without these morbidities.

CONCLUSIONS

Children with fetal brain sparing do not demonstrate a different development of their visual functioning at late school age. However, an abnormal cerebral ultrasound in the neonatal period is associated with impaired visual function in later life.

Ultrasound screening for fetal major abnormalities at 11–14 weeks

BACKGROUND

This study was planned to evaluate the efficiency of the 11-14 week scan in detecting fetuses with major fetal structural abnormalities.

METHODS

Some 1,290 pregnant women were submitted to a routine ultrasound scan between the 11th and 14th week after the detection of the fetal viability. The fetal anatomy was examined transabdominally, and in suspected cases transvaginally. Following the scans, the patients were examined in the second or third trimester of pregnancy. Fetal structural abnormalities classified as major and early onset were noted. Isolated choroid plexus cysts, cardiac defects not requiring treatment, mild ventriculomegaly, and mild renal pelviectasis in second trimester were not included.

RESULTS

Twenty-four (1.86%) fetuses with various defects were identified, and 17 of these were diagnosed at the 11-14 week scan. The antenatal ultrasound detection rate of the fetuses with major anomalies was 95%, and 70% were detected in the first-trimester assessment. Four cardiac defects associated with genetic syndromes or requiring operation were included (0.31%) in this series. Two of the fetuses with cardiac defects (50%) had an increased nuchal translucency thickness. In this group, none of the fetuses with karyotype anomalies was born alive.

CONCLUSIONS

The first-trimester scan is important in routine antenatal care for early detection of fetal defects, and determination of the fetuses at risk of cardiac anomalies and genetic syndromes.

Neue Möglichkeiten in der pränatalen Diagnostik

Mit den technischen Entwicklungen erweiterten sich in den letzten Jahren die Einsatzmöglichkeiten des pränatalen Ultraschalls. So konnten in den 80er und 90er-Jahren zunehmend fetale Fehlbildungen diagnostiziert und spezifiziert werden. Die Untersuchung mit der sonographischen Nackentransparenzmessung in der 11. bis 14. Schwangerschaftswoche findet nunmehr als wichtiges pränatales Screening zur individuellen Risikoabschätzung für Chromosomenstörungen Eingang in die pränatale Medizin. Neben der standardisierten Untersuchungstechnik sollte größter Wert auf die ausführliche Information und Beratung der Schwangeren sowie auf die Qualitätssicherung gelegt werden. Durch die Verbesserung der individuellen Risikospezifizierung mittels Sonographie, biochemischen Markern und dem mütterlichen Alter können unnötige invasive Untersuchungen vermieden und ihre Zahl insgesamt deutlich reduziert werden. Ein Trend, der sich auch anhand des nicht-invasiven Nachweises des fetalen Rhesus D Status und mit dem Einsatz der Dopplersonographie im Management fetaler Anämien verfolgen lässt.

Fetal Mouse Imaging Using Echocardiography: A Review of Current Technology

Advances in genetic research have led to the need for phenotypic analysis of small animal models. However, often these genetic alterations, especially when affecting the cardiovascular system, can result in fetal or perinatal death. Noninvasive ultrasound imaging is an ideal method for detecting and studying such congenital malformations, as it allows early recognition of abnormalities in the living fetus and the progression of disease can be followed in utero with longitudinal studies. Two platforms for fetal mouse echocardiography exist, the clinical systems with 15-MHz phased array transducers and research systems with 20-55-MHz mechanical transducers. The clinical ultrasound system has limited two-dimensional (2D) resolution (axial resolution of 440 microm), but the availability of color and spectral Doppler allows quick interrogations of blood flows, facilitating the detection of structural abnormalities. M-mode imaging further provides important functional data, although, the proper imaging planes are often difficult to obtain. In comparison, the research biomicroscope system has significantly improved 2D resolution (axial resolution of 28 microm). Spectral Doppler imaging is also available, but in the absence of color Doppler, imaging times are increased and the detection of flow abnormalities is more difficult. M-mode imaging is available and equivalent to the clinical ultrasound system. Overall, the research system, given its higher 2D resolution, is best suited for in-depth analysis of mouse fetal cardiovascular structure and function, while the clinical ultrasound systems, equipped with phase array transducers and color Doppler imaging, are ideal for high-throughput fetal cardiovascular screens.

Evolution of fetal ultrasonography

The authors wish to highlight the evolution that has occurred in fetal ultrasound in recent years. A first significant evolution lies in the increasing contribution of first trimester ultrasound for the detection of fetal anomalies. Malformations of several organs and systems have been diagnosed during the first trimester. Furthermore the systematic measurement of the fetal neck translucency has led to increasing rate of detection of aneuploidies and heart malformations. For several years now, three-dimensional (3D) and 4D ultrasound (US) have been used as a complementary tool to 2D US for the evaluation of fetal morphology. This brings an improved morphologic assessment of the fetus. Applications of the techniques are increasing, especially for the fetal face, heart and extremities. The third field where fetal US is continuously providing important information is the knowledge of the natural history of diseases. This has brought significant improvement in the postnatal management of several diseases, especially urinary tract dilatation and broncho-pulmonary malformation.

Trends in fetal echocardiography and implications for clinical practice: 1985 to 2003

OBJECTIVE

The purpose of this study was to determine whether patterns of referral for fetal echocardiography (FE) and the subsequent yield for structural congenital heart disease (CHD) have changed between 1985 and 2003.

METHODS

All FE performed between 1985 and 2003 at Yale-New Haven Hospital was reviewed. The primary indication for study and the presence of structural CHD were recorded, and data were analyzed for trends. Linear regression with Pearson coefficient calculation and Mantel-Haenszel chi(2) analysis were performed (P < .05 significant).

RESULTS

Between 1985 and 2003, 10,806 patients had FE at Yale-New Haven Hospital, and 774 cases of structural CHD were detected. The annual number of studies and rate of detected structural CHD remained constant through the study period. There was a significant increase in the proportion of studies for diabetes, maternal structural CHD, suspicious 4-chamber heart, and family history of cardiac disease. There was a significant decrease in the proportion of studies for a previous child with structural CHD, cardiac teratogen exposure, other fetal anomalies, aneuploidy, fetal arrhythmia, and nonimmune hydrops. The percentage of structural CHD detected by indication remained constant through the study period. Subgroup analysis of diabetes revealed an increase in class B diabetes, while classes C and D remained stable.

CONCLUSIONS

This is one of the largest series of FE and suggests that the pattern of indications has changed since 1985. Specifically, referral for diabetes (mostly class B) has increased without a change in yield of structural CHD by indication for sonography. The changing referral patterns reflect a change in obstetric demographics and has implications for obstetric care.

Three- and 4-dimensional ultrasound in obstetric practice: does it help?

OBJECTIVE

The purpose of this article was to review the published literature on 3-dimensional ultrasound (3DUS) and 4-dimensional ultrasound (4DUS) in obstetrics and determine whether 3DUS adds diagnostic information to what is currently provided by 2-dimensional ultrasound (2DUS) and, if so, in what areas.

METHODS

A PubMed search was conducted for articles reporting on the use of 3DUS or 4DUS in obstetrics. Seven-hundred six articles were identified, and among those, 525 were actually related to the subject of this review. Articles describing technical developments, clinical studies, reviews, editorials, and studies on fetal behavior or maternal-fetal bonding were reviewed.

RESULTS

Three-dimensional ultrasound provides additional diagnostic information for the diagnosis of facial anomalies, especially facial clefts. There is also evidence that 3DUS provides additional diagnostic information in neural tube defects and skeletal malformations. Large studies comparing 2DUS and 3DUS for the diagnosis of congenital anomalies have not provided conclusive results. Preliminary evidence suggests that sonographic tomography may decrease the examination time of the obstetric ultrasound examination, with minimal impact on the visualization rates of anatomic structures.

CONCLUSIONS

Three-dimensional ultrasound provides additional diagnostic information for the diagnosis of facial anomalies, evaluation of neural tube defects, and skeletal malformations. Additional research is needed to determine the clinical role of 3DUS and 4DUS for the diagnosis of congenital heart disease and central nervous system anomalies. Future studies should determine whether the information contained in the volume data set, by itself, is sufficient to evaluate fetal biometric measurements and diagnose congenital anomalies.

Three- and 4-dimensional ultrasound in obstetrics and gynecology: proceedings of the American Institute of Ultrasound in Medicine Consensus Conference

The American Institute of Ultrasound in Medicine convened a panel of physicians and scientists with interest and expertise in 3-dimensional (3D) ultrasound in obstetrics and gynecology to discuss the current diagnostic benefits and technical limitations in obstetrics and gynecology and consider the utility and role of this type of imaging in clinical practice now and in the future. This conference was held in Orlando, Florida, June 16 and 17, 2005. Discussions considered state-of-the-art applications of 3D ultrasound, specific clinical situations in which it has been found to be helpful, the role of 3D volume acquisition for improving diagnostic efficiency and patient throughput, and recommendations for future investigations related to the utility of volume sonography in obstetrics and gynecology.

Tomographic ultrasound imaging of the fetal heart: a new technique for identifying normal and abnormal cardiac anatomy

OBJECTIVE

In 2003 and 2004, the American College of Radiology, the American Institute of Ultrasound in Medicine, and the American College of Obstetricians and Gynecologists published guidelines for the standard ultrasound examination of the fetus. Each group recommended that the outflow tracts of the fetal heart be examined if technically feasible. One method to accomplish this task is to perform a free-hand sweep of the transducer beam directed in a transverse plane from the 4-chamber view to the fetal neck. One problem with this approach is that the examiner may not direct the beam transversely and, therefore, may not accurately identify the outflow tract anatomy.

METHODS

A new technology, tomographic ultrasound imaging (TUI), allows the examiner to obtain a volume data set that simultaneously displays multiple images at specific distances from the 4-chamber view. This study examined TUI technology for identifying normal and abnormal fetal cardiac anatomy with the use of either static or spatiotemporal image correlation volume data sets.

RESULTS

The 4 views used in the screening examination of the outflow tracts of the fetal heart (4-chamber, 5-chamber, 3-vessel, and tracheal views) could be identified with the use of TUI technology in fetuses between 13 and 40 weeks' gestation. Examples of fetuses with abnormal cardiac anatomy of the outflow tracts (tetralogy of Fallot, transposition of the great vessels, and pulmonary stenosis) all showed abnormal anatomy on TUI.

CONCLUSIONS

Tomographic ultrasound imaging technology enables the fetal examiner to evaluate the 4-chamber view and the outflow tracts in a systematic manner to identify normal and abnormal cardiac anatomy.