First and early second-trimester diagnosis of fetal urinary tract anomalies using transvaginal sonography

Predictive accuracy of prenatal ultrasound findings for lower urinary tract obstruction: A systematic review and Bayesian meta-analysis

BACKGROUND

Lower urinary tract obstruction (LUTO) is a rare but critical fetal diagnosis. Different ultrasound markers have been reported with varying sensitivity and specificity.

AIMS

The objective of this systematic review and meta-analysis was to identify the diagnostic accuracy of ultrasound markers for LUTO.

MATERIALS AND METHODS

We performed a systematic literature review of studies reporting on fetuses with hydronephrosis or a prenatally suspected and/or postnatally confirmed diagnosis of LUTO. Bayesian bivariate random effects meta-analytic models were fitted, and we calculated posterior means and 95% credible intervals for the pooled diagnostic odds ratio (DOR).

RESULTS

A total of 36,189 studies were identified; 636 studies were available for full text review and a total of 42 studies were included in the Bayesian meta-analysis. Among the ultrasound signs assessed, megacystis (DOR 49.15, [15.28, 177.44]), bilateral hydroureteronephrosis (DOR 41.33, [13.36,164.83]), bladder thickening (DOR 13.73, [1.23, 115.20]), bilateral hydronephrosis (DOR 8.36 [3.17, 21.91]), male sex (DOR 8.08 [3.05, 22.82]), oligo- or anhydramnios (DOR 7.75 [4.23, 14.46]), and urinoma (DOR 7.47 [1.14, 33.18]) were found to be predictive of LUTO (Table 1). The predictive sensitivities and specificities however are low and wide study heterogeneity existed.

DISCUSSION

Classically, LUTO is suspected in the presence of prenatally detected megacystis with a dilated posterior urethra (i.e., the keyhole sign), and bilateral hydroureteronephrosis. However, keyhole sign has been found to have modest diagnostic performance in predicting the presence of LUTO in the literature which we confirmed in our analysis. The surprisingly low specificity may be influenced by several factors, including the degree of obstruction, and the diligence of the sonographer at searching for and documenting it during the scan. As a result, providers should consider this when establishing the differential for a fetus with hydronephrosis as the presence or absence of keyhole sign does not reliably rule in or rule out LUTO.

CONCLUSIONS

Megacystis, bilateral hydroureteronephrosis and bladder wall thickening are the most accurate predictors of LUTO. Given the significant consequences of a missed LUTO diagnosis, clinicians providing counselling for prenatal hydronephrosis should maintain a low threshold for considering LUTO as part of the differential diagnosis.

Two novel deleterious variants of Angiotensin-I-converting Enzyme gene identified in a family with recurrent anhydramnios

Background

Anhydramnios results from the poor development of the placenta or problems with intrauterine development of the kidneys or urinary tract. Complete lack of amniotic fluid indicates a severe problem with the organs of the urinary system. The genes associated with anhydramnios show very diversity and are not yet well defined.

Methods

Whole‐exome sequencing (WES) was used for an aborted male case around the 20th week of gestation diagnosed with anhydramnios. The resulted deleterious variants were verified by Sanger sequencing. Pathogenicity of deleterious variants was explored by in silico analysis.

Results

A maternally inherited deleterious frameshift variant, c.1454_1455insC, p.(S486Ffs29) in exon 9 and two paternally inherited missense variants c.1037C > G, p.(Ser346Trp) in exon 7 and c.1465A > G, p.(Asn489Asp) in exon 9 of Angiotensin‐I‐Converting Enzyme (ACE) gene were found and confirmed by Sanger sequencing. c.1454_1455insC, p.(S486Ffs29) and c.1037C > G, p.(Ser346Trp) were identified as two novel compound heterozygous deleterious variants. The pathogenicity of these deleterious variants was determined by in silico analysis and both the deleterious variants disrupt the structure of the ACE protein.

Conclusion

Two novel compound heterozygous variants were identified in the case with anhydramnios, which may be associated with pathogenicity of anhydramnios. Our data also revealed that the WES approach may provide helpful information for genetic counseling of the families with anhydramnios.

[Ultrasound of the fetal urinary system during the first trimester of pregnancy]

The detection of abnormalities of the fetal urinary system in the first trimester of pregnancy is constantly improving, namely owing to the improved resolution of the image, the use of the endovaginal approach and thanks to sonographers' constant training. The pathological aspects, usually detected in the second trimester of pregnancy, can be suspected early in the first trimester and range from kidneys' cavity dilation to bilateral renal agenesis, polycystic kidney disease, multi-cystic dysplasia and bladder megavessia or bladder exstrophy. A poly-malformative syndrome is to be found out. The detection of an abnormality of the urinary tract requires a close ultrasound check. Very often, the pathological aspects tend to disappear spontaneously. In particular, the non-visualization of the bladder requires repeated examinations during the same session or even a little later in the pregnancy. We will carry out a review of the literature by pointing out the usual and unusual aspects of the fetal urinary system visible in the first trimester and we will as well propose an algorithm describing how to deal with abnormalities of the urinary tract that can be found out at first trimester ultrasound.

The recurrence of sonographic 'soft markers': ominous sign or 'just' genetics?

OBJECTIVES

'Soft markers' (SMs) are nonspecific findings that might convey a higher risk for Down syndrome. We sought to determine the recurrence rate of the most common SM in subsequent pregnancies.

METHODS

This is a retrospective study of all women who underwent early or late fetal sonographic anatomical screening in our ultrasound unit. The examined SMs were pyelectasis, thickened nuchal fold (TNF) and echogenic intracardiac foci (EIF). Data on recurrence and pregnancy outcome were retrieved retrospectively.

RESULTS

The database included 20 672 singleton pregnancies; SMs were detected in 2347 (11.1%) of the fetuses and were isolated in 1739 (74%). Rates of solitary findings in the pregnancies were 6.5% (1360/20 672) EIF, 3% (624/18 850) TNF and 1.7% (363/20 672) pyelectasis. The recurrence rate of EIF, TNF and pyelectasis in subsequent consecutive pregnancies was 21%, 27% and 16%, respectively. Overall, 62 cases of Down syndrome were diagnosed in (1 : 333 pregnancies). No cases were diagnosed in patients with recurrent SMs.

CONCLUSION

The high recurrence rate of solitary SM implies for genetic predisposition. These results might improve our counseling for pregnant women affected by the reappearance of solitary SM. Further studies are needed to assess the likelihood ratio for SM if recurrence occurs. © 2017 John Wiley & Sons, Ltd.

Impact of antepartum diagnostic amnioinfusion on targeted ultrasound imaging of pregnancies presenting with severe oligo- and anhydramnios: An analysis of 61 cases

OBJECTIVES

The primary objective our study was to assess the role of diagnostic antepartum amnioinfusion on the yield from targeted ultrasounds performed in pregnancies with severe oligo- and anhydramnios.

STUDY DESIGN

This was a retrospective and descriptive study, conducted in the fetal medicine units of two private tertiary care referral centers in south India. The details of all the cases of diagnostic amnioinfusion performed at these two centers from January 2009 to June 2016 were collected and analyzed. Inclusion criteria were pregnancies between 17 and 26 weeks of gestational age with severe oligo- or anhydramnios. Pregnancies with obvious preterm premature rupture of membranes (PPROM) were excluded. The primary outcome measure was the improvement in diagnostic information pertaining to cause of severe oligo- and anhydramnios, and the nature of such anomalies.

RESULTS

A total of 61 cases of were identified. The median gestational age at performance of the procedure was 22 weeks [IQR, 19.5-23]. The mean volume of normal saline infused was 314±54ml. A significant increase in the single vertical pocket (SVP) was observed following the procedure (pre-procedure SVP=0.6±0.9cm, post procedure SVP=3.4±1.7; paired t test, p<0.001). In 37 cases (37/61, 60.7%), there were no pre-procedure ultrasound findings. There was significant overall detection of abnormalities post procedure (mean pre-procedure findings=0.39±0.49, mean post procedure findings=1.59±1.24; paired t test, p<0.001). The most frequent group of anomalies/abnormalities were renal (36/61, 59%), followed by PPROM (13/61, 21.3%) and finally fetal growth restriction (11/61, 18%).

CONCLUSION(S)

Antepartum amnioinfusion is a valuable ancillary technique in prenatal diagnosis as it increases the diagnostic yield from pregnancies presenting with severe oligo- and anhydramnios.

Amniotic Fluid and Maternal Serum Metabolic Signatures in the Second Trimester Associated with Preterm Delivery

Preterm delivery (PTD) represents a major health problem that occurs in 1 in 10 births. The hypothesis of the present study was that the metabolic profile of different biological fluids, obtained from pregnant women during the second trimester of gestation, could allow useful correlations with pregnancy outcome. Holistic and targeted metabolomics approaches were applied for the complementary assessment of the metabolic content of prospectively collected amniotic fluid (AF) and paired maternal blood serum samples from 35 women who delivered preterm (between 29 weeks + 0 days and 36 weeks +5 days gestation) and 35 women delivered at term. The results revealed trends relating the metabolic content of the analyzed samples with preterm delivery. Untargeted and targeted profiling showed differentiations in certain key metabolites in the biological fluids of the two study groups. In AF, intermediate metabolites involved in energy metabolism (pyruvic acid, glutamic acid, and glutamine) were found to contribute to the classification of the two groups. In maternal serum, increased levels of lipids and alterations of key end-point metabolites were observed in cases of preterm delivery. Overall, the metabolic content of second-trimester AF and maternal blood serum shows potential for the identification of biomarkers related to fetal growth and preterm delivery.

Complementary role of magnetic resonance imaging after ultrasound examination in assessing fetal renal agenesis: a case report

INTRODUCTION

Ultrasonography is used routinely during pregnancy to screen and detect fetal abnormalities. However, there are some conditions like anhydramnios (a prevalent state in renal agenesis) or maternal obesity that may limit the diagnostic accuracy of ultrasonography. Magnetic resonance imaging has proven to be useful when ultrasound alone is insufficient to make a correct diagnosis.

CASE PRESENTATION

We present the case of a 22-year-old Caucasian woman who was admitted to our unit at the 26th week of gestation for a detailed anatomy scan. Anhydramnios and failure to visualize the kidneys, bladder and renal vessels were confirmed with the use of sonography in our department. Since the lack of amniotic fluid limited the acoustic window for fetal ultrasonography, a magnetic resonance imaging scan was requested to confirm suspected renal agenesis. A fetal magnetic resonance imaging scan was performed and confirmed the suspected diagnosis. A baby boy was born by breech vaginal delivery after spontaneous onset of labor at the 34th week of gestation. The boy weighed 1690g, with Apgar scores of 6 and 4 at two and five minutes respectively, and died one hour after delivery. The diagnosis of bilateral renal agenesis was confirmed on autopsy.

CONCLUSIONS

The aim of this study was to evaluate the potential contribution of magnetic resonance imaging in diagnostic procedure after inconclusive ultrasound examination during the assessment of fetal urinary tract abnormalities in the third trimester.

Detection of structural abnormalities in the first trimester using ultrasound

During the past 25 years, embryonic and early fetal ultrasound and diagnosis have increasingly gained attention in pregnancy care. Modern high-frequency ultrasound transducers make it possible to obtain detailed images of the early conceptus and its organs, and thus move part of the anatomy and anomaly scan from the second to the first trimester. Today, detection of embryonic and fetal structural abnormalities in the first trimester has frequently been reported. One has to distinguish between diagnosis during the early period until about 10 weeks when the embryo or early fetus is small and transvaginal ultrasound is applied, and diagnosis during the late period at the nuchal translucency screening, usually carried out using transabdominal ultrasound. Early first-trimester abnormalities are often diagnosed by chance on clinical indications, whereas late first-trimester diagnoses are the result of systematic screening using ultrasound markers.

Early pregnancy scanning for fetal anomalies--the new standard?

For many years, significant efforts have been made toward attempts at early detection of chromosomal and structural malformations, to lower the rate of these defects in newborns. Traditionally, the main ultrasound examination during pregnancy was performed in the second trimester, using transabdominal transducers. The development of high-frequency and high-resolution (5 to 9 MHz; 6 to 12 MHz) transvaginal probes along with substantial improvements in image and signal processing have opened new possibilities for the investigation of early pregnancy. Up until the recent past, many defects were considered unidentifiable early in pregnancy. A large number of those can now be diagnosed already in the first trimester. Early detection of fetal anomalies enables karyotyping by chorionic villus sampling and, in those patients in whom findings are abnormal, simpler procedures for termination of pregnancy may be performed. This may reduce physical and psychological morbidity associated with second-trimester abortions.

First trimester ultrasound: current approaches and practical pitfalls

Revolutionary technological improvements and high-frequency transvaginal scanning have enabled the resolution of ultrasound imaging in the first trimester to increase such that detailed early fetal development can now be well visualized. This investment in imaging technology has enabled not only normal embryonic development but also chromosomal abnormalities and structural anomalies to be more easily and accurately diagnosed before the second trimester. This article is intended to help radiologists in the interpretation and clinical application of normal and abnormal first trimester ultrasound findings in early pregnancy. We review the current literature and applications and interpretations of first trimester ultrasound.

[Early fetal megacystis at first trimester: a six-year retrospective study]

OBJECTIVE

A fetal megacystis is defined by a longitudinal bladder diameter more than 7 mm. The purpose of this study is to describe the prenatal ultrasound findings of this early fetal pathology and to assess pronostic and aetiologycal criteria.

PATIENTS AND METHODS

Between January 2003 and December 2008, 12 cases of early fetal megacystis were identified in our referral fetal medicine unit (Saint-Etienne hospital, France).

RESULTS

There were two cases of spontaneous resolution and one case wasn't a fetal megacystis. Termination of pregnancy for medical indications was realised for another cases because of associated malformations and bad evolution (six cases) and three chromosomal abnormalities (two cases of trisomy 18 and one of trisomy 21).

DISCUSSION AND CONCLUSION

Sonographic follow-up and fetal karyotyping are important to evaluate prognosis. However, our data suggest that fetal megacystis is a severe condition when diagnosed in early pregnancy.

First-trimester ultrasound: current uses and applications

This article is aimed to aid the sonographer and medical care provider in better interpretation and clinical application of first-trimester ultrasound findings in early pregnancy. We review current uses, applications, and interpretations of first-trimester ultrasound. A discussion of basic embryology and normal as well as abnormal first-trimester sonographic findings are discussed. We also cover the utility of the first-trimester ultrasound in screening for fetal aneuploidy. Attention is also given to the role of the first-trimester ultrasound in the prediction of adverse perinatal and maternal outcomes.

First trimester ultrasonography in screening and detection of fetal anomalies

An obstetrical ultrasound examination provides invaluable information regarding the fetus. Until the mid-1980s, ultrasound in the first trimester was limited to localization of the pregnancy, establishing viability, and accurate dating. With the advent of high-resolution ultrasound and transvaginal scanning, a significant amount of information about the fetus can be gained and provided to the patient at a very early stage in gestation. This article provides an overview of the role of first trimester (11-13 + 6 weeks' gestation) ultrasound in screening and diagnosis of fetal anomalies. The first trimester is an ideal time for screening for aneuploidy, primarily due to the advantages that nuchal translucency (NT) measurement provides. NT measurement is also useful in establishing the risk of congenital cardiac disorders and a number of genetic and non-genetic syndromes. Significant NT thickening is associated with an increase in perinatal morbidity and mortality. Potential mechanisms resulting in increased NT are discussed. A number of new ultrasound markers for fetal aneuploidy have been investigated over the past several years, some of which appear to improve the screening efficacy of early ultrasonography. The role of these is reviewed. A number of fetal anomalies can now be consistently diagnosed in the first trimester. Their appearance at this early gestational age is discussed as well. It is clear that, data obtained by first trimester ultrasound are useful in counseling expectant parents and in planning the appropriate follow-up.

Prenatal diagnosis of horseshoe kidney by measurement of the renal pelvic angle

OBJECTIVE

The aim of this study was to evaluate the usefulness of measurement of the angle between bilateral renal pelves on axial views in the prenatal ultrasonographic diagnosis of horseshoe kidney.

METHODS

We retrospectively measured the renal pelvic angle in 19 fetuses with horseshoe and 20 fetuses with normal kidneys in the second and third trimesters. Renal pelvic angle was defined as the angle between the long axis of the renal pelves on the axial view of the abdomen. We compared the renal pelvic angles of horseshoe and normal kidneys with unpaired t-test. Taking 140 degrees as a cut-off value, we calculated the sensitivity, specificity and accuracy of pelvic angle measurement for the prenatal diagnosis of horseshoe kidney.

RESULTS

The mean pelvic angles in the fetuses with horseshoe kidney were 116 degrees and 110 degrees in the second and third trimester, respectively. In the normal fetuses, the equivalent angles were 172 degrees and 161 degrees. The difference between the two groups was statistically significant (P < 0.01). Using 140 degrees as the discriminating criterion, the sensitivity, specificity and accuracy of renal pelvic angle measurement for the prenatal diagnosis of horseshoe kidney were all 100%. Fifteen of 19 fetuses with horseshoe kidney had no other abnormality. Four (21%) fetuses had severe complex abnormalities which were associated with trisomy 18 in three cases.

CONCLUSION

Observation and measurement of the renal pelvic angle is a simple and useful method in the prenatal diagnosis of the horseshoe kidney.

Determining the incidence of horseshoe kidney from radiographic data at a single institution

PURPOSE

An estimated 150,000 children are born with birth defects each year. One of the most frequent genitourinary abnormalities is horseshoe kidney (HSK). The incidence of HSK in the population is estimated to be 1/400 to 1,600 births based on autopsy data from the 1940s and 1950s. We prospectively evaluated the incidence of HSK based on radiographic studies to determine the contemporary incidence of HSK.

MATERIALS AND METHODS

In a 6-month period patients undergoing abdominal computerized tomography, renal ultrasonography and excretory urography were screened for HSK. After identification medical charts were reviewed for demographics, history, study indication and findings. A literature review of 12 studies of 825 patients with HSK was compared with the current series with regard to common associated findings.

RESULTS

From 15,320 radiographs 23 patients were identified with HSK for an overall incidence of 1/666. Computerized tomography, excretory urography and ultrasound identified 16, 5 and 2 patients, respectively, while 16 were male, 7 were female, 20 were adults and 3 were children. The most common concomitant urological disorder was nephrolithiasis in 9 patients (39%), prompting operative intervention in 4. The radiographic incidence of HSK closely matched data from autopsy series and yet it differed from that in current radiographic series using ultrasound in the perinatal period.

CONCLUSIONS

Our radiographic evaluation of the HSK incidence closely matches past autopsy series. This finding suggests that the incidence of HSK remains stable despite an increasing number of birth defects. Moreover, it appears that radiographic studies can accurately estimate the incidence of congenital anatomical disorders. Our data suggest that HSK is a relatively benign condition with a low requirement for operative intervention in these incidentally identified patients.

Ultrasound detection of first trimester malformations: a pictorial essay

Knowledge of normal and abnormal anatomy in the first trimester aids in early detection of anomalies and the avoidance of potential pitfalls.

First trimester anatomy scan: pushing the limits. What can we see now?

PURPOSE OF REVIEW

The aim of this review article is to familiarize the reader with the current developments dealing with ultrasound during the first trimester of pregnancy.

RECENT FINDINGS

The main emphasis of this article is to review the anatomy seen during the first trimester and to bring to the reader the fact that the first anatomical survey of the fetus does not have to wait until the 18th to 20th week of gestation. The fetus can be surveyed adequately as early as the 12th week of gestation and ideally between the 13th and 14th weeks. Of course, not all malformations will be detected during the first trimester, and a follow-up scan between 20 and 23 weeks is indicated.

SUMMARY

The ongoing improvements in ultrasound technology allow us to see more details of the embryo or fetus at earlier gestational ages than ever before. This is resulting in a rethinking of when the first anatomical survey should be performed.

Vesicocentesis at 10-14 weeks of gestation for treatment of fetal megacystis

This report of four cases shows that fetal vesicocentesis at 10-14 weeks of gestation is a useful treatment option in some cases with megacystis. Although megacystis at this gestation has been reported, there are few studies examining the role of early vesicocentesis. The natural history of the condition and outcome following treatment is reviewed with reference to the literature.

Prenatal diagnosis and management of abnormalities in the urologic system

We have reviewed the prenatal diagnosis and management of abnormalities in the urologic system. Urologic anomalies may be caused by embryologic aberrations, genetic disease, or a nonrandom association with other structural abnormalities. There is a wide range of prognoses, depending on the cause and the impact of the anomaly on the production of amniotic fluid. Management focuses on obtaining an accurate prenatal diagnosis, providing appropriate counseling, and ensuring the proper surveillance or treatment before and after birth.

First trimester malformation screening

First trimester fetal malformation screening still represents a diagnostic challenge in modem obstetrics. Being solely dependent on ultrasound instrumentation, and the skill and experience of the operator, recently improved by introducing high frequency transvaginal approach and digital image processing. This opens a new field of ultrasound in obstetrics called sonoembriology. Until now sonoembriology in routine clinical practice resulted in numerous reports about early detection of rare anomalies and uncommon syndromes. The reported sensitivity of sonoembriology with a respect to a final pregnancy outcome was more than 60% of all malformations in total, while in combination with ultrasound screening in second trimester, increases to in excess of 80%. The commonest anomalies detected by sonoembriology are anomalies of the head and brain, heart, abdominal wall, unbilical cord, urinary tract and skeleton. There is an important role of sonoembriology in the assessment of the nuchal translucency in the screening programme for chromosomal anomalies. This changes the well-known concept "fetus as a patient" to "embryo as a patient" and opens new frontiers in fetal diagnosis and therapy.

Involution rate of multicystic renal dysplasia

OBJECTIVE

To document the involution rate and long-term results of management of multicystic dysplastic kidney.

MATERIALS AND METHODS

Data were collected retrospectively for all 23 infants (16 boys) with multicystic dysplastic kidney who were treated at our center over the last 19 years (1977-1995). The diagnosis was based on prenatal ultrasound in 18 patients and on palpable abdominal mass in 5, and confirmed in all patients by postnatal ultrasound and radioisotope scan. Voiding cystography was performed in 18 patients to exclude vesicoureteral reflux. Mean follow-up was 46 months (range, 3 months to 5 years) and included serum creatinine measurements and renal ultrasonography.

RESULTS

Two groups of patients were identified. Ten (43.6%) with other urologic abnormalities (group A) and 13 patients without other urologic abnormalities (group B). Vesicoureteral reflux was observed in 4 patients. Nephrectomy was performed in 4 patients, all from group B. The other 19 patients were treated conservatively. Complete involution was observed in 8 patients in group A and 6 in group B after a mean follow-up period of 9.2 and 10 months, respectively. Two patients, 1 from each group, later underwent nephrectomy not because of no involution but because of an increase in the size of the kidney involved.

CONCLUSION

Patients with multicystic renal dysplasia have significant associated urologic malformations, and the natural history of the disease is unpredictable. All patients require appropriate investigation of the urinary tract and long-term follow-up. The most outstanding finding of the study is the much higher involution rate of multicystic renal dysplasia and the rate of associated urologic abnormalities than that reported in the literature. Surgery remains an option for the patients in the absence of no involution. multicystic dysplastic kidney, surgery, conservative.

Prenatal diagnosis. Therapeutic implications

Prenatal diagnosis of structural anomalies provides the opportunity to influence the postnatal outcome. The greatest value of antenatal screening is, in fact, the awareness of the urogenital abnormalities, such as presumed UPJ obstruction, so that appropriate investigation and treatment can be offered immediately after birth and before permanent damage occurs owing to obstruction or infection. Crombleholme and coworkers reported that prenatal consultation impacted favorably on outcomes by preventing early termination of pregnancy owing to misconceptions about the existing condition. It also permitted delivery of complex cases in a tertiary care setting, thereby preventing a delay in postnatal management. A systematic approach to the infant in the prenatal and postnatal periods is important. The natural history of prenatally detected hydronephrosis continues to be defined, and there is no ideal test to predict the outcome of UPJ obstruction. Several investigators are evaluating various markers in urine that may help to identify fetuses who require early postnatal intervention. More complete understanding regarding the natural history of unilateral pediatric UPJ obstruction and its response to surgery will not be available until several randomized, prospective clinical studies are completed. The collaborative effort of obstetricians, neonatologists, geneticists, radiologists, and pediatric urologists should provide answers to many questions surrounding prenatally diagnosed UPJ obstruction.

First trimester ultrasonographic diagnosis of fetal structural abnormalities in a low risk population

OBJECTIVES

Ultrasonographic screening between 12(+0) and 13(+6) weeks for fetal structural abnormalities using transabdominal sonography and, where necessary, transvaginal sonography in a low risk population.

DESIGN

A prospective observational study.

SETTING

London teaching hospital.

METHODS

Pregnant women with a total of 1632 low risk viable fetuses between 12(+0) and 13(+6) weeks of gestation were scanned using transabdominal and, where necessary, transvaginal sonography (40%). If the anatomical survey was normal, the women underwent routine 18-20 week anomaly scans. Pregnancy outcomes were obtained from radiological and neonatal computerised databases, and postal or telephone patient enquiry.

RESULTS

Seventeen (1.0%) major structural abnormalities were diagnosed in the study group. Of these, 11 (64.7%) were diagnosed at the 12-13 week scan, three diagnosed in the mid-trimester and three postnatally. Of the fetal abnormalities diagnosed antenatally, 78.6% were diagnosed in the first trimester. The sensitivity of abnormality detection by the combination of both first and second trimester scans was 82.3%. In addition, a significant number of missed abortions (n = 36) were also diagnosed by the first trimester scan.

CONCLUSION

This study has demonstrated the potential of screening a low risk population for fetal abnormalities at 12-13 weeks of gestation using transabdominal sonography and, where necessary, transvaginal sonography. Larger studies are required to establish the clinical value of the first trimester scan.

Postnatal management of hydronephrosis diagnosed in utero

In this review we identify the causes of antenatal hydronephrosis and detail management options. A large majority of these patients can be treated safely and effectively after birth.

Minimal hydronephrosis in the fetus: clinical significance and implications for management

PURPOSE

We further define the natural history and management of minimal fetal hydronephrosis.

MATERIALS AND METHODS

Experience with minimal fetal hydronephrosis (renal pelvic diameter 4 to 10 mm. before 20 weeks of gestation and 5 to 10 mm. from 20 to 24 weeks) was reviewed for 18 months at New England Medical Center.

RESULTS

The incidence of minimal fetal hydronephrosis was 2.2% in the 5,900 fetuses screened by ultrasound. In 63% of cases prenatal ultrasound was done more than once, and revealed that dilatation of the urinary tract was stable during gestation in 31 (25%), and became normal in 35 (29%) and worse in 11 (9%). A total of 63 patients (103 renal units) followed for up to 1 year underwent postnatal sonography. Those with abnormalities were screened with a voiding cystourethrogram and renal scan, including 40 with normal postnatal ultrasound and no changes on subsequent evaluation. Of the 23 patients with abnormal findings 4 had functionally significant ureteropelvic junction obstruction and 1 had severe vesicoureteral reflux. A retrospective analysis of the sonograms of patients with minimal fetal hydronephrosis and persistence or progression of hydronephrosis revealed calicectasis, progression of minimal fetal hydronephrosis in utero and/or abnormal renal echogenicity in each fetus.

CONCLUSIONS

Our study shows that in a small but significant number of fetuses minimal fetal hydronephrosis will progress, whereas in most it will resolve.

The significance of early second-trimester sonographic detection of minor fetal renal anomalies

A study of 6350 consecutive transvaginal ultrasound examinations was performed as part of a routine fetal evaluation. Twenty-one cases (0.33 per cent) of early second-trimester sonographic detection of minor renal abnormalities (unilateral renal agenesis, pelvic kidney, and double collecting system) are presented. The sonographic diagnosis was made at 14-18 weeks of pregnancy and confirmed, in all of the 21 fetuses, postnatally or by post-mortem. A high incidence of associated fetal anomalies (24 per cent) and parental renal abnormalities (14 per cent) was demonstrated. Transvaginal sonography was found to be a useful tool for diagnosing these renal anomalies as early as 14 weeks of pregnancy. The likelihood of various associated anomalies and long-term implications on renal function raise questions concerning the prenatal management of such patients.

The early prenatal sonographic diagnosis of renal agenesis: techniques and possible pitfalls

Out of 13,252 cases in which fetal bilateral echogenic kidneys were detected by transvaginal sonography between 12 and 18 weeks' gestation, there were nine fetuses where oval hypoechogenic masses were detected in the renal bed. In five fetuses where hypoechogenic masses in the renal bed were sonographically visualized, postabortal examination was compatible with renal agenesis and the hypoechogenic masses proved to be enlarged adrenals. In three additional cases, unilateral renal agenesis was accompanied by unilateral enlarged adrenals, radiologically confirmed postnatally. In one case, a false-positive sonographic diagnosis of Potter syndrome was made because of bilateral hypoechogenic masses in the renal bed. Postabortal examination detected hypoplastic kidneys, but of normal histology, in a dyskaryotic fetus with trisomy 22. In four cases of renal agenesis, the amniotic fluid was of normal volume until the 17th week. In two of the five cases of Potter syndrome, a cystic structure, compatible with the urinary bladder, was detected in the pelvis at 14 weeks. The diagnostic criteria for renal agenesis in the early fetus differ from those used in the second half of gestation.

Pathogenesis of megalourethra

Idiopathic megalourethra in infants is an enlargement of the pendulous urethra with no evidence of distal obstruction. Two aborted fetuses at 14 and 19 weeks of gestational age exhibited megalourethra with definite complete distal obstruction. The urethras of these 2 fetuses were studied histologically confirming the presence of an uncanalized epithelial core in the glans obstructing the lumen of the patent urethra. Embryologically, this epithelial core is normal but early canalization achieves continuity with the lumen of the penile urethra. In these 2 fetuses canalization was arrested or delayed with complete obstruction of the urethra in the glans and dilatation of the pendulous urethra. In living children with this form of megalourethra the urethra of the glans is patent. Canalization of the epithelial core in the glans of the survivors may have been delayed rather than arrested and may be a cause of megalourethra.

Transvaginal sonography-detection of findings suggestive of fetal chromosomal anomalies in the first and early second trimesters

Over a 4-year period, 14 dyskaryotic fetuses were diagnosed by amniocentesis, performed after early detection of malformations using transvaginal sonography (TVS). These 14 dyskaryotic fetuses were detected out of 4878 sonographic screenings performed by TVS between 9 and 16 weeks' gestation. Twenty-eight per cent of the referrals were at high risk and 72 per cent were at low risk for fetal malformations. Two hundred and twenty-nine fetuses (4.7 per cent) of the screened population had 265 anomalies, 39 per cent of them being transient. In 7 of the 14 dyskaryotic fetuses (50 per cent), the sonographically detected anomalies were transient, being undetected by follow-up sonographic screenings at later gestational ages (greater than or equal to 18 weeks). Postponing the first sonographic scan aimed at malformation detection to a later gestational age may lead to transient anomalies and their associated dyskaryosis being missed.

Clues and pitfalls in the early prenatal diagnosis of 'late onset' infantile polycystic kidney

Infantile polycystic kidney disease (IPKD) is an autosomal recessive inherited disorder, IPKD has been previously diagnosed by us as early as the 14th week of gestation. 'Late onset' (third trimester) IPKD has been previously described by several authors. We present here a case of intrauterine detection of 'late onset' IPKD, suggesting that elongated hyperechogenic kidneys (with normal transverse and anteroposterior diameters) should be considered as an early sign of 'late onset' presenting IPKD.