Ultrasound Diagnosis of Malformations of the Fetal Kidneys and Urinary System

Malformations of the fetal kidneys and urinary system are common and easily visualized and diagnosed on ultrasound. This article presents the typical sonographic findings of these abnormalities during the various stages of pregnancy. Because malformations of the urogenital tract often have an association with genetic diseases/ciliopathies, these are also discussed. To complete the article, we provide a brief overview of the normal anatomy of the kidneys and urinary system. The normal anatomy and malformations of the genitalia will not be discussed in this article due to their complexity.

DEGUM Recommendations on Diagnostic Puncture in Prenatal Medicine

Diagnostic puncture (amniocentesis, chorionic villus sampling, and fetal blood sampling) is an essential part of prenatal diagnostics and the only established and sufficiently scientifically evaluated possibility of diagnosing genetic diseases from pregnancy-specific cells. The number of diagnostic punctures in Germany, as in other countries, has fallen significantly. This is largely due to the introduction of first-trimester screening with further detailed ultrasound examination of the fetus and the analysis of cf-DNA (cell-free DNA) from maternal blood (noninvasive prenatal test - NIPT). On the other hand, knowledge about the incidence and appearance of genetic diseases has increased. The development of modern molecular genetic techniques (microarray and exome analysis) makes a differentiated investigation of these diseases increasingly possible. The requirements for education and counseling regarding these complex correlations have thus increased. The studies performed in recent years make it clear that diagnostic puncture performed in expert centers is associated with a low risk of complications. In particular, the procedure-related miscarriage risk hardly differs from the background risk for spontaneous abortion. In 2013, the Section of Gynecology and Obstetrics of the German Society for Ultrasound in Medicine (DEGUM) published recommendations on diagnostic puncture in prenatal medicine 1. The developments described above and new findings in recent years make it necessary to revise and reformulate these recommendations. The aim of this review is to compile important and current facts regarding prenatal medical puncture (including technique, complications, genetic examinations). It is intended to provide basic, comprehensive, and up-to-date information on diagnostic puncture in prenatal medicine. It replaces the publication from 2013 1.

Basic Gynecologic Ultrasound Examination (Level I): DEGUM, ÖGUM, and SGUM Recommendations

Ultrasound has become an essential diagnostic tool in gynecology, and every practicing gynecologist must be able to differentiate normal from pathologic findings, such as benign or malignant pelvic masses, adnexal torsion, pelvic inflammation disease, endometriosis, ectopic pregnancies, and congenital uterine malformations at least on a basic level. A standardized approach to the correct settings of the ultrasound system, the indications for gynecologic ultrasound investigations, and the sonographic appearance of normal anatomy and common pathologic findings in the standard planes are important prerequisites for safe and confident clinical management of gynecologic patients. Based on current publications and different national and international guidelines, updated DEGUM, ÖGUM, and SGUM recommendations for the performance of basic gynecologic ultrasound examinations were established.

Basic Gynecologic Ultrasound Examination (Level I): DEGUM, ÖGUM, and SGUM Recommendations

Ultrasound has become an essential diagnostic tool in gynecology, and every practicing gynecologist must be able to differentiate normal from pathologic findings, such as benign or malignant pelvic masses, adnexal torsion, pelvic inflammation disease, endometriosis, ectopic pregnancies, and congenital uterine malformations at least on a basic level. A standardized approach to the correct settings of the ultrasound system, the indications for gynecologic ultrasound investigations, and the sonographic appearance of normal anatomy and common pathologic findings in the standard planes are important prerequisites for safe and confident clinical management of gynecologic patients. Based on current publications and different national and international guidelines, updated DEGUM, ÖGUM, and SGUM recommendations for the performance of basic gynecologic ultrasound examinations were established.

Multicenter clinical experience with non-invasive cell-free DNA screening for monosomy X and related X-chromosome variants

OBJECTIVE

We aimed to investigate how the presence of fetal anomalies and different X chromosome variants influences Cell-free DNA (cfDNA) screening results for monosomy X.

METHODS

From a multicenter retrospective survey on 673 pregnancies with prenatally suspected or confirmed Turner syndrome, we analyzed the subgroup for which prenatal cfDNA screening and karyotype results were available. A cfDNA screening result was defined as true positive (TP) when confirmatory testing showed 45,X or an X-chromosome variant.

RESULTS

We had cfDNA results, karyotype, and phenotype data for 55 pregnancies. cfDNA results were high risk for monosomy X in 48/55, of which 23 were TP and 25 were false positive (FP). 32/48 high-risk cfDNA cases did not show fetal anomalies. Of these, 7 were TP. All were X-chromosome variants. All 16 fetuses with high-risk cfDNA result and ultrasound anomalies were TP. Of fetuses with abnormalities, those with 45,X more often had fetal hydrops/cystic hygroma, whereas those with "variant" karyotypes had different anomalies.

CONCLUSION

Both, 45,X or X-chromosome variants can be detected after a high-risk cfDNA result for monosomy X. When there are fetal anomalies, the result is more likely a TP. In the absence of fetal anomalies, it is most often an FP or X-chromosome variant.

Turner syndrome-omphalocele association: Incidence, karyotype, phenotype and fetal outcome

OBJECTIVE

Omphalocele is known to be associated with genetic anomalies like trisomy 13, 18 and Beckwith-Wiedemann syndrome, but not with Turner syndrome (TS). Our aim was to assess the incidence of omphalocele in fetuses with TS, the phenotype of this association with other anomalies, their karyotype, and the fetal outcomes.

METHOD

Retrospective multicenter study of fetuses with confirmed diagnosis of TS. Data were extracted from a detailed questionnaire sent to specialists in prenatal ultrasound.

RESULTS

680 fetuses with TS were included in this analysis. Incidence of small omphalocele in fetuses diagnosed ≥12 weeks was 3.1%. Including fetuses diagnosed before 12 weeks, it was 5.1%. 97.1% (34/35) of the affected fetuses had one or more associated anomalies including increased nuchal translucency (≥3 mm) and/or cystic hygroma (94.3%), hydrops/skin edema (71.1%), and cardiac anomalies (40%). The karyotype was 45,X in all fetuses. Fetal outcomes were poor with only 1 fetus born alive.

CONCLUSION

TS with 45,X karyotype but not with X chromosome variants is associated with small omphalocele. Most of these fetuses have associated anomalies and a poor prognosis. Our data suggest an association of TS with omphalocele, which is evident from the first trimester.

Quality Requirements for gynecological ultrasound examinations of DEGUM level II - Recommendations of the Sections/Working Groups Gynecology and Obstetrics of DEGUM, ÖGUM and SGUM

Gynecological sonography is the central and most frequently used technical examination method used by gynecologists. Its focus is on the clarification of masses of the uterus and the adnexa, fertility diagnosis, clarification of bleeding disorders and chronic and acute pelvic problems, pelvic floor and incontinence diagnosis as well as the differential diagnosis of disturbed early pregnancy. The indication for diagnostic and therapeutic interventions, preoperative planning and postoperative controls are largely based on the findings of gynecological sonography. These examinations are particularly dependent on the experience of the examiner.Based on the proven multi-stage concept of obstetric diagnostics, gynecological sonography should primarily be performed by an experienced and specialized examiner in patients for whom the initial gynecological examinations have not yet led to a sufficient assessment of the findings. So that the expert status required for this has an objective basis, the Gynecology and Obstetrics Section of DEGUM in cooperation with ÖGUM and SGUM implemented the option of acquiring DEGUM Level II for gynecological sonography. The effectiveness of the care in the multi-level concept depends on the quality of the ultrasound examination at level I. Quality requirements for the basic examination and the differentiation between the basic and further examination have therefore already been defined by DEGUM/ÖGUM. The present work is intended to set out quality requirements for gynecological sonography of DEGUM level II and for the correspondingly certified gynecologists.Common pathologies from gynecological sonography and requirements for imaging and documentation are described.

Doppler ultrasound in pregnancy - quality requirements of DEGUM and clinical application (part 2)

This second part on Doppler sonography in prenatal medicine and obstetrics reviews its clinical applications. While this has not become the initially anticipated screening tool, it is used for the diagnosis and surveillance of a variety of fetal pathologies. For example, the sonography-based determination of uterine artery blood flow indices is an important parameter for the first trimester multimodal preeclampsia risk assessment, increasing accuracy and providing indication for the prophylactic treatment with aspirin. It also has significant implications for the diagnosis and surveillance of growth-restricted fetuses in the second and third trimesters through Doppler-sonographic analysis of umbilical artery, middle cerebral artery and ductus venosus. Here, especially the hemodynamics of the ductus venosus provides a critical criterium for birth management of severe, early-onset FGR before 34 + 0 weeks of gestation. Further, determination of maximum blood flow velocity of the middle cerebral artery is a central parameter in fetal diagnosis of anemia which has been significantly improved by this analysis. However, it is important to note that the mentioned improvements can only be achieved through highest methodological quality. Importantly, all these analyses are also applied to twins and higher order multiples. Here, for the differential diagnosis of specific complications such as TTTS, TAPS and TRAP, the application of Doppler sonography has become indispensable. To conclude, the successful application of Doppler sonography requires both exact methodology and precise pathophysiological interpretation of the data.

Editorial

Dear Colleagues,

Now you get a new Issue of Ultrasound International Open. As always you can find a mixture of different articles dealing with the main topic ultrasound.

Ratio of fetal choroid plexus to head size: simple sonographic marker of open spina bifida at 11-13 weeks' gestation

OBJECTIVES

To measure the ratio of choroid plexus (CP) size to head size in normal fetuses and to compare it to that in fetuses with open spina bifida (OSB) and quantify the subjective sign of a 'dry brain'.

METHODS

This was a retrospective study of ultrasound images, obtained during first-trimester screening between 11 and 13 weeks of gestation, from 34 fetuses with OSB and 160 normal fetuses. From the hospital databases, we retrieved images of the fetal head in the transventricular axial plane. We measured the areas of both CPs and the head and calculated the ratio between them. We also measured the longest diameter of each CP and calculated their mean (CP length), and measured the occipitofrontal diameter (OFD) and calculated the ratio of CP length to OFD. Measurements from the OSB fetuses were plotted on crown-rump length (CRL) reference ranges constructed using data from the normal fetuses, and Z-scores were calculated.

RESULTS

In the normal fetuses, the CP area increased, while the ratios of CP area to head area and CP length to OFD decreased, with increasing CRL. In 30 of the 34 (88%) fetuses with OSB, both ratios were increased significantly and the CPs filled the entirety of the head, giving the impression of a dry brain. In these cases, the borders of the lateral ventricles could not be identified.

CONCLUSIONS

At 11-13 weeks, the majority of fetuses with OSB have reduced fluid in the lateral ventricles such that the CPs fill the head. The dry brain sign is easily visualized during routine first-trimester ultrasound examination while measuring the biparietal diameter, and can be quantified by comparing the size of the CPs to the head size. Until prospective data confirm the usefulness of this sign in screening for OSB, it should be considered as a hint to prompt the examiner to assess thoroughly the posterior fossa and spine. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

[Doppler Sonography during Pregnancy - DEGUM Quality Standards and Clinical Applications]

Doppler sonography is widely established in prenatal medicine and obstetrics and is commonly used in screening for aneuploidy and preeclampsia during the first trimester. More importantly, during the 2nd and 3 rd trimester, it is used in the assessment of fetal health as well as the surveillance of underlying fetal conditions such as IUGR and anemia. Correct use of the method is vital for correct data interpretation and the inferred clinical decision process. Therefore, we aim to provide all users of doppler sonography with a guide for meeting the required quality standards. These quality standards will further be the basis of DEGUM-certified training courses. In the first part, we will introduce the technical principles of the method and potential error sources, vascular disciplines to which the method can be applied, analysis of the spectral curves, patient safety and the needed requirements for successful certification.

Cavum septi pellucidi (CSP) ratio: a marker for partial agenesis of the fetal corpus callosum

OBJECTIVE

While complete agenesis of the corpus callosum is often suspected on fetal ultrasound due to absence of the cavum septi pellucidi (CSP), suspicion of partial agenesis of the corpus callosum (pACC) is a challenge since the CSP is almost always present. The aim of this study was to measure the length and width of the CSP and calculate the length-to-width ratio (CSP ratio), and compare these between fetuses with pACC and normal fetuses.

METHODS

In this retrospective case-control study, the length and width of the CSP were measured in the axial plane of the fetal head, and the CSP length-to-width ratio calculated, in 323 normal fetuses and in 20 fetuses with pACC between 20 and 34 weeks' gestation. From the normal population we constructed reference ranges in relation to biparietal diameter (BPD). For all fetuses we calculated Z-scores for the CSP ratio.

RESULTS

In the normal population, the length and width of the CSP increased with increasing BPD, while the CSP ratio decreased. The CSP was short (< 5^th centile) in 85% (17/20) of fetuses with pACC and wide (> 95^th centile) in 65% (13/20). The CSP ratio was small (< 5^th centile) in 95% (19/20) of pACC fetuses, with 16/20 (80%) having a ratio below an empirical cut-off of 1.5. Analysis of Z-scores showed that fetuses with pACC had a significantly smaller CSP ratio (P < 0.0001) compared with the normal population.

CONCLUSIONS

Fetuses with a normal-sized corpus callosum have a rectangular-shaped CSP, with a CSP ratio > 1.5 in the second half of gestation. Most fetuses with pACC have an abnormally shaped, wide and short CSP, with a decreased CSP ratio. This simple ratio has the potential to identify fetuses at high risk for pACC. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Ultrasound of the Fetal Veins Part 3: The Fetal Intracerebral Venous System

The study of the intracerebral venous system in the fetus can only be achieved by means of high-resolution ultrasound equipment with sensitive color Doppler. In the past two decades, there has been a growing interest in the ultrasound examination of the fetal brain with few studies reporting on the brain vasculature during various stages of gestation. In comparison to other fetal venous systems, reports on the assessment of the fetal cerebral venous system are still scarce. This article presents a review on the fetal intracranial venous system with detailed discussions on the anatomy of the superficial and deep cerebral veins. Color Doppler of the main fetal cerebral veins to include the superior sagittal sinus, the straight sinus, the vein of Galen, the internal cerebral veins, the transverse sinuses and others is also discussed. Furthermore, this article highlights abnormal clinical conditions such as aneurysm of the vein of Galen, thrombosis of the dural sinus and variation in the course of some veins such as the straight sinus and falcine sinus. The role of pulsed Doppler examination in normal and growth-restricted fetuses is also discussed.

Maxillary gap at 11-13 weeks' gestation: marker of cleft lip and palate

OBJECTIVE

To describe a new sign of cleft lip and palate (CLP), the maxillary gap, which is visible in the mid-sagittal plane of the fetal face used routinely for measurement of nuchal translucency thickness.

METHODS

This was a retrospective study of stored images of the mid-sagittal view of the fetal face at 11-13 weeks' gestation in 86 cases of CLP and 86 normal controls. The images were examined to determine if a maxillary gap was present, in which case its size was measured.

RESULTS

In 37 (43.0%) cases of CLP the defect was isolated and in 49 (57.0%) there were additional fetal defects. In the isolated CLP group, the diagnosis of facial cleft was made in the first trimester in nine (24.3%) cases and in the second trimester in 28 (75.7%). In the group with additional defects, the diagnosis of facial cleft was made in the first trimester in 46 (93.9%) cases and in the second trimester in three (6.1%). A maxillary gap was observed in 96% of cases of CLP with additional defects, in 65% of those with isolated CLP and in 7% of normal fetuses. There was a large gap (>1.5 mm) or complete absence of signals from the maxilla in the midline in 69% of cases of CLP with additional defects, in 35% of those with isolated CLP and in none of the normal controls.

CONCLUSIONS

The maxillary gap is a new simple marker of possible CLP, which could increase the detection rate of CLP, especially in isolated cases.

Ultrasound of the fetal veins part 1: the intrahepatic venous system

Advances in high-resolution ultrasound combined with color Doppler and three-dimensional (3 D) rendering have contributed to an increasing understanding of the fetal venous circulation in recent years. Still the sonographic evaluation of the venous system in the fetus remains difficult. This article reviews the normal and abnormal intrahepatic venous system. Normal anatomy and abnormal findings of the umbilical vein (UV), the ductus venosus (DV), portal veins, hepatic veins and the inferior vena cava are demonstrated by grayscale, color Doppler and 3D ultrasound and explained by numerous schemes. Typical variants and abnormalities such as agenesis of the DV and portal venous system, persistence of the right UV, UV varix are explained and the clinical value of normal and abnormal Doppler findings in the DV is discussed. Many of these abnormal findings can be detected by a targeted examination of the intrahepatic vasculature with means of color Doppler.

Small biparietal diameter in fetuses with spina bifida on 11-13-week and mid-gestation ultrasound

OBJECTIVES

To assess whether, at 11-13-week and mid-trimester ultrasound examinations, the biparietal diameter (BPD) in fetuses with open spina bifida is smaller than the reference range.

METHODS

In a multicenter retrospective analysis of data from 23 fetuses with open spina bifida diagnosed at 16-24 weeks, BPD at diagnosis was compared with that measured at 11-13 weeks, before diagnosis. Z-scores were calculated for comparison of BPD deviations from the reference range within the groups at 11-13 weeks and 16-24 weeks, and between these two time intervals.

RESULTS

BPD Z-scores at 11-13 weeks and 16-24 weeks were significantly lower (P < 0.0001) in fetuses with open spina bifida when compared to the reference range, with mean values of - 1.29 and - 2.14, respectively, corresponding to the 10(th) and 1.5(th) centiles, respectively. At 11-13 weeks only six of the 23 (26%) fetuses with open spina bifida had BPD below the 5(th) centile, in comparison to 16 (69%) at mid-gestation. This was confirmed by paired t-test comparing the first-trimester with the second-trimester BPD measurements, which showed significantly slower growth of the BPD in fetuses with spina bifida.

CONCLUSION

In fetuses with open spina bifida, BPD is smaller not only in the second trimester, as previously reported, but also in the first trimester. This is most likely due to loss of cerebrospinal fluid. We suggest that a BPD value < 10(th) centile in an otherwise normally grown fetus at 11-13 weeks' gestation should be considered as a potential subtle early marker for open spina bifida.

[Fetal neurosonography using 3-dimensional multiplanar sonography]

This review focuses on the examination of the fetal brain, using three-dimensional (3D) ultrasound and the multiplanar rendering mode (MPR). The routine examination of the brain is achieved with axial planes but a dedicated fetal neurosonogram requires additional coronal and sagittal views, in order to provide a complete view of the different brain structures. Because these planes are difficult to obtain under many conditions, the present paper shows how 3D MPR allows one to obtain 1 or multiple reconstructed images from a digital volume. The display can be either as orthogonal planes, tomographic planes with parallel slices or as one single plane of the region of interest, which can be selected by the examiner. This approach allows easily the demonstration of the corpus callosum, the cerebellar vermis, the three-horn view, the foetal hippocampus and other regions. In addition, early neurosonography of the developing brain from the 7th week of pregnancy onwards can be achieved.

Prospective detection of open spina bifida at 11-13 weeks by assessing intracranial translucency and posterior brain

We describe a case series of six fetuses with open spina bifida (OSB) from four different prenatal units, where the anomaly was detected at the routine 11-13-week ultrasound examination. Crown-rump length ranged from 49 to 78 mm. All cases were first suspected during nuchal translucency thickness measurement in the mid-sagittal plane of the face. OSB was lumbosacral in five fetuses and cervical in one. The intracranial translucency (IT) was obliterated in two cases, but some fluid was found in the other four cases. However, in all cases the typical landmarks of a normal posterior brain and normal IT were absent. In all six cases the ratio of brainstem diameter to brainstem-occipital bone distance was increased (≥ 1). This detection of an abnormal posterior brain led to a targeted examination and detection of the spinal lesion during the same examination in five cases, whereas in one suspicious case the patient was recalled at 17 weeks, when the abnormality was detected. Two fetuses had both multiple anomalies and trisomy 18. These prospective cases demonstrate the feasibility of using the standard mid-sagittal plane commonly used for NT measurement to assess the IT and the posterior brain and to determine the presence of OSB during NT screening.

Assessment of intracranial translucency (IT) in the detection of spina bifida at the 11-13-week scan

OBJECTIVE

Prenatal diagnosis of open spina bifida is carried out by ultrasound examination in the second trimester of pregnancy. The diagnosis is suspected by the presence of a 'lemon-shaped' head and a 'banana-shaped' cerebellum, thought to be consequences of caudal displacement of the hindbrain. The aim of the study was to determine whether in fetuses with spina bifida this displacement of the brain is evident from the first trimester of pregnancy.

METHODS

In women undergoing routine ultrasound examination at 11-13 weeks' gestation as part of screening for chromosomal abnormalities, a mid-sagittal view of the fetal face was obtained to measure nuchal translucency thickness and assess the nasal bone. In this view the fourth ventricle, which presents as an intracranial translucency (IT) between the brain stem and choroid plexus, is easily visible. We measured the anteroposterior diameter of the fourth ventricle in 200 normal fetuses and in four fetuses with spina bifida.

RESULTS

In the normal fetuses the fourth ventricle was always visible and the median anteroposterior diameter increased from 1.5 mm at a crown-rump length (CRL) of 45 mm to 2.5 mm at a CRL of 84 mm. In the four fetuses with spina bifida the ventricle was compressed by the caudally displaced hindbrain and no IT could be seen.

CONCLUSION

The mid-sagittal view of the face as routinely used in screening for chromosomal defects can also be used for early detection of open spina bifida.

Follow-up of unilateral multicystic kidney dysplasia after prenatal diagnosis

OBJECTIVES

Since the introduction of antenatal diagnostic screening, multicystic kidney dysplasia (MCKD) has been diagnosed in 1 of 4300 live births. We analyze our own experience and demonstrate a management regime based on these results and existing studies.

METHODS

Retrospective data analysis was carried out in 110 patients, prenatally diagnosed with MCDK. A total of 93 patients with confirmed diagnosis of unilateral MCDK were born alive and followed up in our institutions.

RESULTS

A total of 110 unilateral cystic kidneys were prenatally diagnosed; 93 were confirmed postnatally. These children were retrospectively allocated to two treatment groups: 51 were operated upon; 42 were treated conservatively. A micturition cystourethrogram was performed 88 times, yielding 20 pathological findings. Vesicoureteral reflux was identified 11 times (12.5%). Eleven children (12%) had associated non-urological abnormalities. Cardiac and musculoskeletal malformations predominated. After 1995, nephrectomy was performed only when clinically indicated. Thirty-seven children were treated conservatively for between 4 months and 6 years (mean 33 months); 28 dysplastic kidneys exhibited size reduction. Complete involution was noted in 16 of 28 children between 7 and 29 months (mean 16.2 months).

CONCLUSION

This study provides evidence that neonatal nephrectomy of unilateral MCDK is rarely required. It also shows that the discussed malformation is not an isolated developmental abnormality. In a high proportion, associated urogenital abnormalities were present and therapeutically relevant, and determined the overall prognosis.

Three-dimensional ultrasound in prenatal diagnosis

PURPOSE OF REVIEW

Several technological advances have greatly improved three-dimensional sonography, which have improved acquisition and display capabilities. This review describes these technical changes as well as current applications of 3D sonography in prenatal diagnosis.

RECENT FINDINGS

Recently published papers have emphasized the potential of getting a precise 'any plane of choice' from a three-dimensional volume, as a new way of scanning, based on the off-line analysis of a volume dataset. Surface mode has been used to demonstrate malformations and genetic diseases. The maximum rendering mode, which highlights bones, has great potential for imaging the nasal bones and the frontal bones with the metopic suture. Organ volume can be measured, but the utility of this in clinical practice remains to be determined. Three-dimensional ultrasound needs to be standardized.

SUMMARY

Three-dimensional ultrasonography is the most rapidly developing technique in fetal imaging. New features will permit the transition from the era of 'sonography in two-dimensional planes' to 'volume ultrasound'.

[Basics of 3D and 4D fetal echocardiography using spatial and temporal image correlation (STIC) software]

Spatio-temporal image correlation (STIC) is a new 3D technique allowing the acquisition of a volume of the beating fetal heart. It is the first reliable technique allowing a routine 4D fetal echocardiography. This paper reviews the principles of this new technique and its potential. Once a volume is acquired and stored, it can be rendered in different display modes. The volume information can be displayed as a multiplanar image (A, B, and C planes) and allows the visualisation of an "anyplane". The information in the volume can be used to reconstruct a 3D rendering of the heart according to an examiner-defined volume of interest. Some of these rendering modes are explained in this paper, such as surface rendering, minimum mode, inversion mode and glass body mode (combination of STIC with colour or power Doppler).

New developments in fetal heart scanning: three- and four-dimensional fetal echocardiography

This article reviews the possibilities of three- and four-dimensional (3- and 4D) fetal echocardiography. A volume data set of a fetal heart can be acquired as a static volume, as a real-time 3D volume or as an offline 4D volume cine using spatial and temporal image correlation (STIC) software. STIC is explained and the potentials of this modality are emphasized. The display of a fetal heart volume data set demonstrates the cross-sections of interest, using the multiplanar mode or tomographic multislice imaging, and different volume rendering tools. The latter include: surface, minimum, inversion and glass body modes. This review highlights the potential of acquiring a digital volume data set of a heart cycle for later offline evaluation, either for an offline diagnosis, a second opinion (e.g. via Internet link) or for teaching fetal echocardiography to trainees and sonographers.

[Prenatal diagnosis of right atrial isomerism (asplenia-syndrome): case report]

Right atrial isomerism (earlier known as asplenia) is a group of malformations including anomalies of the heart and the visceral organs. Complex defects of the heart are normally found, but these are non-specific. The suspected diagnosis can be confirmed most easily by focusing on a specific and segmental examination of the heart. We report on a fetus referred at 22 weeks in whom AV-septal defect was detected. Heart and stomach were on the left side, but the segmental approach allowed the detection of juxtaposed descending aorta and inferior vena cava as typical signs of right isomerism. The suspected malformation could be verified by the additional detection of infra-diaphragmatic total anomalous pulmonary venous drainage by using colour Doppler. Howell-Jolly bodies from fetal blood supported the diagnosis of asplenia. Autopsy after termination of pregnancy demonstrated the typical signs of right isomerism. The paper reviews the typical prenatal findings which lead to the detection of right isomerism in the fetus. Segmental approach should be performed in each fetus with an anomaly of the heart especially in the presence of complex defects.

Reliability of the lung-to-head ratio in predicting outcome and neonatal ventilation parameters in fetuses with congenital diaphragmatic hernia

OBJECTIVES

The ratio of the lung area (on the contralateral side of the hernia) to the head circumference, the lung-to-head ratio (LHR), has been proposed as a reliable tool in the assessment of the prognosis of congenital diaphragmatic hernia (CDH). An LHR < 0.6 has been associated with poor outcome whereas one > 1.4 has been associated with survival. We aimed to analyze the role of LHR in predicting fetal outcome and ventilation parameters in cases of isolated CDH in our center.

METHODS

During the 40-month study period, 22 fetuses with an isolated CDH were delivered alive under optimized conditions at our perinatal center. LHR was measured at the time of diagnosis (median, 27 weeks' gestation). In addition to survival, postnatal ventilation parameters including pCO2, pO2, inspiratory O2 partial pressure, inspiratory pressure and oxygenation index were determined, as was the occurrence of pulmonary hypertension.

RESULTS

The overall survival rate was 59%. The LHR was not able to predict fetal outcome reliably. There was no correlation between the liver herniation, LHR and fetal outcome. The prenatally determined lung size reflected in the LHR did not show any significant association with individual ventilation parameters. Eleven of 17 infants examined had signs of pulmonary hypertension and the LHR did not predict this condition.

CONCLUSION

Our study cannot support the optimistic results reported by other groups on the use of LHR as a reliable predictor of outcome in fetuses with CDH. The LHR, as a reflection of lung size, correlates neither with survival patterns nor with various postnatal ventilation parameters.

Aberrant right subclavian artery as a new cardiac sign in second- and third-trimester fetuses with Down syndrome

OBJECTIVE

The right subclavian artery arises normally as the first vessel from the brachiocephalic artery of the aortic arch. An aberrant right subclavian artery arises as a separate vessel from the aortic isthmus and crosses to the right, behind the trachea. This variant is present in <1% of the normal population; however, in subjects with Down syndrome, an incidence between 19% and 36% was reported. The purpose of this study was to assess the possibility of the detection of an aberrant right subclavian artery in fetuses with Down syndrome.

STUDY DESIGN

Fourteen consecutive fetuses with prenatally detected Down syndrome were examined between 18 and 33 weeks of gestation. The presence of an aberrant right subclavian artery was determined by visualization of the transverse 3-vessel trachea view of the upper thorax with color Doppler ultrasonography.

RESULTS

The right subclavian artery was visualized in 100% of fetuses (14/14) with Down syndrome. An aberrant right subclavian artery was identified in 35.7% of trisomy 21 fetuses (5/14). In 1 fetus, the aberrant right subclavian artery was the only abnormal ultrasound finding. In 3 fetuses, an aberrant right subclavian artery was associated with an intracardiac echogenic focus plus additional extracardiac markers. In the fourth fetus, an aberrant right subclavian artery was associated with an atrioventricular septal defect. All 9 fetuses with Down syndrome with a normal origin of the right subclavian artery had additional cardiac and/or extracardiac abnormalities. In 12 cases, pregnancy was terminated; 2 fetuses were live born.

CONCLUSION

This preliminary study suggests that the in utero identification of an aberrant right subclavian artery may be a new ultrasound marker to be found in fetuses with Down syndrome. Further studies are required to assess the incidence of aberrant right subclavian artery in normal fetuses.

Posterior Urethral Valves: Prenatal Diagnostic Signs and Outcome

INTRODUCTION

Urethral valves can be of enormous clinical importance. Both the prognosis for an affected fetus and the indication for a prenatal therapeutic intervention depend to a high degree on the accuracy of the prenatal diagnosis.

PATIENTS AND METHODS

The sonographic findings and the results of the postnatal diagnostic workup of 24 boys treated for urethral valves in our institute are analyzed in the present paper.

RESULTS

Out of a group of 900 children, diagnosed prenatally as having urinary tract anomalies, the postnatal diagnostic workup revealed 24 boys suffering from posterior urethral valves. The combination of megacystis, oligohydramnios, and bilateral renal abnormalities was present in 3 boys, and it was only in these cases that urethral valves were correctly identified as the underlying pathology. The largest group (n = 16) of these fetuses presented with bilateral hydronephrosis with and without megaureter. Megacystis in any combination with other findings was detected only in 4 patients. Oligohydramnios as a sign of impaired renal function was observed in four pregnancies. Four children suffered postnatally from beginning renal insufficiency. Eight infants (33%) required some form of respiratory support. This group included the 4 newborns with oligohydramnios during the pregnancy.

CONCLUSIONS

Posterior urethral valves represent a rare but severe congenital malformation. They can disrupt the development of the entire urinary tract and may be life-limiting to the affected boy. Only rarely, however, are they manifested as the complete pathological picture on prenatal ultrasound. In most cases, bilateral impairment of the fetal renal development suggests severe subvesical obstruction. Thus in cases with bilateral renal impairment on prenatal ultrasonography, posterior urethral valves are to be excluded postnatally. Oligohydramnios is a predictor of a poor outcome of the renal function.

Advanced dynamic flow -- a new method of vascular imaging in prenatal medicine. A pilot study of its applicability

INTRODUCTION

Vascular imaging by means of colour Doppler sonography is an established method in prenatal diagnostics, especially in fetal echocardiography. In recent years, new techniques for the imaging of vessels have been developed, attaining B-scan quality. One example of such techniques is the Advanced Dynamic Flow. The goal of the study was the comparison of the practical application of ADF under routine conditions with the established colour Doppler method, on the same machine.

AIM OF THE STUDY

Comparison of conventional colour Doppler sonography with Advanced Dynamic Flow.

STUDY DESIGN

a prospective, systematic study.

PATIENTS AND METHOD

We used a representative cross-section through the fetal vessels and also carried out complete fetal echocardiography. Between January 1 (st), 2002 and December 31 (st), 2002, 100 pregnant women between the 12 (th) to 40 (th) gestational week were examined.

RESULTS

The success rate for visualisation of blood flow was the same or higher for Advanced Dynamic Flow in all areas, compared with conventional colour Doppler. These results could also be achieved in fetal echocardiography.

CONCLUSION

The Advanced Dynamic Flow technique is a new method for vascular imaging with B-scan quality. It offers high resolution, good lateral discrimination and high sensitivity. The present prospective study has demonstrated that ADF achieves better vascular imaging than conventional colour Doppler sonography. The fact that ADF offers an almost three-dimensional imaging of vessels is particularly valuable. The ease of use of the ADF technique qualifies this method as a serious alternative to conventional colour Doppler sonography.

Three-dimensional (3D) and 4D color Doppler fetal echocardiography using spatio-temporal image correlation (STIC)

OBJECTIVE

Color Doppler echocardiography is used to visualize three transverse planes: the four-chamber, five-chamber, and three vessels and trachea views. Color Doppler spatio-temporal image correlation (STIC) is a new three-dimensional (3D) technique allowing the acquisition of a volume of data from the fetal heart that is displayed as a cineloop of a single cardiac cycle. The aim of the study was to examine the potential of color Doppler STIC to evaluate normal and abnormal fetal hearts.

METHODS

This prospective study included 35 normal fetuses and 27 fetuses with congenital heart defects (CHD) examined between 18 and 35 weeks of gestation. Volume acquisition was achieved by initiating the image capture sequence from the transverse four-chamber view. Volumes were stored for later offline evaluation using a personal computer-based workstation in a multiplanar mode and as spatial volume rendering.

RESULTS

Successful acquisition was possible in all 62 cases. The three planes could be demonstrated in 31/35 healthy fetuses and in 24/27 fetuses with CHD. Spatial volume rendering was attempted in 18 fetuses with CHD. In the four normal fetuses with inadequate visualization using color Doppler STIC, the region of interest was perpendicular to the ultrasound beam. In two fetuses with CHD inadequate visualization was related to an enlarged heart in late gestation, in which the entire cardiac volume could not be acquired. The third case was an 18-week fetus with complex CHD and transposed great vessels in which artifacts were related to confluent color signals as a result of low resolution in the reconstructed plane.

CONCLUSIONS

STIC in combination with color Doppler ultrasound is a promising new tool for multiplanar and 3D/4D rendering of the fetal heart. Limitations may be found later in gestation in fetuses with large hearts and early in gestation as a result of low discrimination of signals. In addition, insonation perpendicular to the structure of interest does not image color Doppler signals and should be avoided during acquisition.

Detection of an aneurysm of the vein of Galen following signs of cardiac overload in a 22-week old fetus

OBJECTIVES

To present early prenatal diagnosis of an aneurysm of the Vein of Galen by detecting signs of cardiac overload in a 22-week old fetus.

CASE

We report on a 22-week old fetus presenting with dilation of the heart, tricuspid and mitral valve regurgitation, reversed flow in the aortic arch and dilated neck vessels. Evaluation of the fetal brain revealed a dilated left ventricle, signs of brain hemorrhage and an anechoic structure between the two hemispheres.

METHODS

By using the conventional Doppler technique, an intracerebral fistula and dilated vein of Galen was visualized. The complex vascular structure was demonstrated using 3-D color power angiography (3-D CPA). To our knowledge, this is the earliest diagnosis of this vascular malformation.

CONCLUSION

Although signs of cardiac overload rarely appear before the third trimester in cases of arteriovenous fistulae, it was shown that these signs could lead to the correct diagnosis of an aneurysm of the vein of Galen. Additionally, we show that 3-D CPA is a promising technique to visualize complex vascular structures and make them easier to understand.

Meconium peritonitis and pseudo-cyst formation: prenatal diagnosis and post-natal course

OBJECTIVES

Intra-uterine bowel perforation can occur secondary to a variety of abnormalities and cause sterile peritonitis in the fetus (generalised = type I). If sealing of the perforation does not take place, a thick-walled pseudo-cyst can form (type II).

METHODS

Over a 12-year period, 21 616 pregnancies were screened for gastro-intestinal malformations using prenatal ultrasound. We identified 1077 cases suspicious of surgically correctable malformations. Post-natal diagnoses and outcome were worked up retrospectively.

RESULT

We found 96 fetuses with suspected gastro-intestinal malformations. Prenatal bowel perforation with meconium peritonitis was confirmed in 11 cases. In 5 of these 11, the correct diagnosis had been predicted prenatally. One child presented as a fetal and neonatal emergency (case report). Ten of the eleven infants were operated on during their first day of life. Intra-operative findings were atresia (n = 4), meconium ileus (n = 6) and no obvious cause (n = 1). Two children suffered fatal complications.

CONCLUSION

Meconium peritonitis and meconium pseudo-cysts as its special manifestation are assessable by prenatal diagnosis but present in different ways. They can present as fetal ascites or echogenic bowel and cause fetal or neonatal distress, requiring close observation and highly specialised care.

[Retrospective analysis of differential therapeutic measures in children with double kidney and ureter and hydronephrosis]

In this study, we analyzed the findings of 79 duplex kidneys in 64 children treated at our institution between 1987 and 1999. Several reasons for impaired urine transport in a duplex kidney were clarified. A total of 55% of all patients manifested a variety of abnormal findings during prenatal screening. In the course of postnatal diagnostic work-up, renal units were classified according to their leading pathomorphological features: 44% showed a ureterocele, 29% nonfunctioning units at first diagnosis, and 27% vesicoureteric reflux. Nonfunctioning moieties had been heminephrectomized in most cases. In such nonfunctioning cases in the presence of associated ureteroceles, relief drainage was unsuccessful in our study. Reflux rarely matures. Ureterocystoneostomy is successful in 80% of our cases. In functioning units with a ureterocele, endoscopic therapy may be the one and only intervention needed. However, they commonly require secondary reconstructive measures.

Caliber of the coronary sinus in fetuses with cardiac defects with and without left persistent superior vena cava and in growth-restricted fetuses with heart-sparing effect

OBJECTIVE

To assess reference ranges for fetal coronary sinus (CS) diameter and to compare them with values from fetuses showing heart defects with and without left superior vena cava (LSVC) as well as with severe intrauterine growth retardation and heart-sparing effect on color Doppler.

METHODS

The coronary sinus was visualized on two-dimensional ultrasound in a plane slightly caudal to the apical four-chamber view. For the normal range of the size of the CS in relation to gestational age, data was collected from 108/114 (95%) normal fetuses with good visualization between 20 weeks' gestation and term. Abnormal conditions comprised two groups: group 1 consisted of 52 fetuses with heart anomalies, including three subgroups: 11 fetuses with isolated LSVC emptying into the coronary sinus, 12 fetuses with LSVC associated with structural heart defects and 29 fetuses with structural heart defects but without LSVC. Group 2 consisted of 11 fetuses with severe intrauterine growth retardation and dilated coronary arteries as seen by color Doppler ultrasound.

RESULTS

Under normal conditions, there was a significant increase in the CS diameter with advancing gestational age (1.2-2.7 mm). Significant dilatation was found only in the two groups with LSVC (range 2.7-6.5 mm), independent of whether the finding was isolated or associated with cardiac defects.

CONCLUSION

CS visualization and measurements are easily feasible in the human fetus in the apical four-chamber view. Significant dilatation of the CS is a sign of LSVC. The examiner should be aware of this condition as such dilatation is commonly falsely diagnosed as atrial or atrioventricular septal defect.