Prenatal diagnosis of bilateral isolated fetal hyperechogenic kidneys. Is it possible to predict long term outcome?

Reversed cortico-medullary differentiation in the fetal and neonatal kidneys: an indicator of poor prognosis?

BACKGROUND

Bilateral reversed cortico-medullary differentiation is rarely observed on fetal or neonatal renal ultrasound and is therefore a diagnostic challenge.

OBJECTIVE

Our purpose was to widen the differential diagnoses of fetal and neonatal nephropathies introducing reversed cortico-medullary differentiation as a clue either on obstetric US or during follow-up of hyperechoic kidneys in order to improve the management of such rare clinical situations.

MATERIALS AND METHODS

We retrospectively reviewed the US images of 11 patients showing bilateral reversed cortico-medullary differentiation on prenatal examination or in which this pattern developed postnatally in the follow-up of fetal hyperechoic kidneys. For each patient, a precise diagnosis was established either on clinical assessment or, when available, on histological or genetic findings.

RESULTS

Six fetuses displayed bilateral reversed cortico-medullary differentiation on obstetric examination, and the pattern persisted throughout pregnancy. In the five other fetuses, the kidneys appeared initially homogeneously hyperechoic; this evolved into reversed cortico-medullary differentiation during the third trimester in two cases and shortly after birth in three cases. Two pregnancies were terminated because of estimated poor prognosis. In the nine surviving neonates, four died of renal failure in the post-natal period. The clinical evolution was more favorable in the remaining five newborns.

CONCLUSIONS

Six different diagnoses were established in patients presenting with a reversed cortico-medullary differentiation renal pattern. This finding was associated with poor outcome in six cases. An acute prenatal diagnosis of reversed cortico-medullary differentiation improves pre- and postnatal work-up and guides counseling and genetic testing.

Fetal hyperechoic kidney cohort study and a meta-analysis

Objective: To investigate the positive rate of chromosomal and monogenic etiologies and pregnancy outcomes in fetuses with hyperechoic kidney, and to provide more information for genetic counseling and prognosis evaluation. Methods: We performed a retrospective analysis of 25 cases of hyperechoic kidney diagnosed prenatal in the Second Affiliated Hospital of Harbin Medical University and Harbin Red Cross Central Hospital (January 2017-December 2022). Furthermore, we conducted a meta-analysis of a series of hyperechoic kidneys (HEK) in the literature to assess the incidence of chromosomal and monogenic etiologies, mortality, and pooled odds ratio (OR) estimates of the association between the incidence of these outcomes and other associated ultrasound abnormalities. Results: 25 fetuses of HEK were enrolled in the cohort study, including 14 with isolated hyperechoic kidney (IHK) and 11 with non-isolated hyperechoic kidney (NIHK). Chromosomal aneuploidies were detected in 4 of 20 patients (20%). The detection rate of pathogenic or suspected pathogenic copy number variations (CNVs) was 29% (4/14) for IHK and 37% (4/11) for NIHK. Whole exome sequencing (WES) was performed in 5 fetuses, and pathogenic genes were detected in all of them. The rate of termination of pregnancy was 56% in HEK. 21 studies including 1,178 fetuses were included in the meta-analysis. No case of abnormal chromosome karyotype or (intrauterine death)IUD was reported in fetuses with IHK. In contrast, the positive rate of karyotype in NIHK was 22% and that in HEK was 20%, with the ORs of 0.28 (95% CI 0.16-0.51) and 0.25, (95% CI 0.14-0.44), respectively. The positive rate of (chromosome microarray analysis) CMA in IHK was 59% and that in NIHK was 32%, with the ORs of 1.46 (95% CI 1.33-1.62) and 0.48 (95% CI, 0.28-0.85), respectively. The positive rate of monogenic etiologies in IHK was 31%, with the OR of 0.80 (95% CI 0.25-2.63). In IHK, the termination rate was 21% and neonatal mortality was 13%, with the ORs of 0.26 (95% CI, 0.17-0.40), 1.72 (95% CI, 1.59-1.86), and that in NIHK was 63%, 0.15 (95% CI, 0.10-0.24); 11%, 0.12 (95% CI, 0.06-0.26), respectively. The intrauterine mortality in NIHK group was 2%, with the OR of 0.02 (95% CI, 0.01-0.05). HNF1B variant has the highest incidence (26%) in IHK. Conclusion: The positive rate of karyotype was 20% in HEK and 22% in NIHK. The positive rate of CMA was 32% in NIHK and 59% in IHK. The positive rate of IHK monogenic etiologies was 31%. HNF1B gene variation is the most common cause of IHK. The overall fetal mortality rate of NIHK is significantly higher than that of IHK. The amount of amniotic fluid, kidney size and the degree of corticomedullary differentiation have a great impact on the prognosis, these indicators should be taken into consideration to guide clinical consultation and decision-making.

Prenatal diagnosis in the fetal hyperechogenic kidneys: assessment using chromosomal microarray analysis and exome sequencing

Fetal hyperechogenic kidneys (HEK) is etiologically a heterogeneous disorder. The aim of this study was to identify the genetic causes of HEK using prenatal chromosomal microarray analysis (CMA) and exome sequencing (ES). From June 2014 to September 2022, we identified 92 HEK fetuses detected by ultrasound. We reviewed and documented other ultrasound anomalies, microscopic and submicroscopic chromosomal abnormalities, and single gene disorders. We also analyzed the diagnostic yield of CMA and ES and the clinical impact the diagnosis had on pregnancy management. In our cohort, CMA detected 27 pathogenic copy number variations (CNVs) in 25 (25/92, 27.2%) fetuses, with the most common CNV being 17q12 microdeletion syndrome. Among the 26 fetuses who underwent further ES testing, we identified 7 pathogenic/likely pathogenic variants and 8 variants of uncertain significance in 9 genes in 12 fetuses. Four novel variants were first reported herein, expanding the mutational spectra for HEK-related genes. Following counseling, 52 families chose to continue the pregnancy, and in 23 of them, postnatal ultrasound showed no detectable renal abnormalities. Of these 23 cases, 15 had isolated HEK on prenatal ultrasound. Taken together, our study showed a high rate of detectable genetic etiologies in cases with fetal HEK at the levels of chromosomal (aneuploidy), sub-chromosomal (microdeletions/microduplications), and single gene (point mutations). Therefore, we speculate that combined CMA and ES testing for fetal HEK is feasible and has good clinical utility. When no genetic abnormalities are identified, the findings can be transient, especially in the isolated HEK group.

A meta-analysis of pregnancy outcomes in the diagnosis of isolated foetal renal parenchyma by prenatal ultrasonography

BACKGROUND

To effectively circumvent foetal structural abnormalities and serious newborn sequelae, antenatal ultrasound evaluation can support making an early diagnosis for potential prenatal management or the termination of pregnancy.

OBJECTIVE

This study systematically evaluated a meta-analysis of different pregnancy outcomes in the diagnosis of isolated foetal renal parenchymal echogenicity (IHEK) by prenatal ultrasonography.

METHODS

Two researchers conducted a literature search following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The following databases were included in the search: China National Knowledge Infrastructure, Wanfang Medical Network, China Academic Journals Full-text Database, PubMed, Web Of Science and Springer Link; additional library websites were also included, and the search reviewed different pregnancies among patients with IHEK. The outcome indicators were the live birth rate, the incidence of polycystic renal dysplasia and the incidence of pregnancy termination/neonatal death. The meta-analysis was performed using the Stata/SE 12.0 software.

RESULTS

A total of 14 studies were included in the meta-analysis (total sample content, 1,115 cases). The combined effect size of prenatal ultrasound diagnosis of pregnancy termination/neonatal mortality in patients with IHEK was 0.289 (confidence interval (CI) 95%; range, 0.102-0.397). The combined effect size of the live birth rate of pregnancy outcomes was 0.742 (CI 95%; range, 0.634-0.850. The combined effect size of the polycystic kidney dysplasia rate was 0.066 (CI 95%; range, 0.030-0.102). The heterogeneity of all three results was > 50%; accordingly, a random-effects model was used.

CONCLUSION

The indications for eugenic labour should not be included in a prenatal ultrasound diagnosis of patients with IHEK. In the results of this meta-analysis, the live birth and polycystic dysplasia rates were optimistic in terms of pregnancy outcomes. Therefore, under the condition of excluding other unfavourable factors, it is necessary to A thorough technical inspection is required to make an accurate judgment.

Antenatally Diagnosed Kidney Anomalies

Congenital anomalies of the kidney and urinary tract encompass a broad spectrum of developmental conditions that together account for the majority of childhood chronic kidney diseases. Kidney abnormalities are the most commonly diagnosed congenital anomaly in children, and detection of this anomaly is increasing as a result of improved antenatal care and widespread access to more sensitive screening ultrasonography. Most paediatricians will encounter children with congenital kidney anomalies across a wide spectrum of disorders, and a broad understanding of the classification, investigation, and basis of management is important to appropriately direct their care.

Differential Diagnosis and Prognosis of Fetuses with Bilateral Enlarged, Hyperechogenic Kidneys: Renal Volume and Amniotic Fluid Volume with Advancing Gestation

INTRODUCTION

This study's objective was to identify prenatal criteria helping differential diagnosis of bilateral enlarged, hyperechogenic kidneys, especially looking at development of renal volume and amniotic fluid volume with increasing gestational age.

METHOD

Retrospective analysis (single-center database) of all bilateral enlarged, hyperechogenic kidneys between 2000-2018. Renal enlargement was defined as renal volume>90^th percentile. Evaluation included development of renal and amniotic fluid volume during pregnancy and fetal outcome.

RESULTS

23 cases fulfilled the inclusion criteria. 12 pregnancies were terminated. For 11 continued pregnancies, longitudinal information on amniotic fluid volume and renal volume were available. 4 cases with oligohydramnios showed a progressive reduction; 6 cases with normal/increased amniotic fluid volume remained stable; in 1 case amniotic fluid volume normalized from initially being oligohydramnios. Regarding renal volume, 4 cases showed exponential enlargement, 3 cases linear progression; in 2 cases renal volume stabilized after initial progression; 2 cases showed initial progression and secondary regression. 4 fetuses survived: 3 autosomal dominant polycystic kidney diseases, 1 Bardet-Biedl syndrome.

CONCLUSION

Progressive reduction of amniotic fluid volume with exponential increase of renal volume is highly suggestive for autosomal recessive polycystic kidney disease. Cases of autosomal dominant polycystic kidney disease show a linear progression of renal volume>90^th percentile and mostly normal amniotic fluid volume.

Perinatal and infant outcome of fetuses with prenatally diagnosed hyperechogenic kidneys

OBJECTIVE

Hyperechogenic kidneys are a relatively rare antenatal finding, which can generate significant parental anxiety due to uncertain prognosis. We report on the perinatal and infant outcomes of a large cohort of fetuses with antenatally diagnosed hyperechogenic kidneys.

METHODS

This was a retrospective analysis of all cases diagnosed prenatally with hyperechogenic kidneys between 2002 and 2017 in a large tertiary fetal medicine unit. Hyperechogenicity was defined as kidney parenchyma with greater echogenicity than that of the liver. Pregnancy, pathological and postnatal outcomes were collected from hospital and general practitioner records up to 1 year of age. Abnormal renal outcome was defined as elevated creatinine beyond 6 months of age, hypertension requiring medication or major kidney surgery, such as nephrectomy. Severe abnormal renal outcome was defined as the need for dialysis or kidney transplant at any stage.

RESULTS

Three-hundred and sixteen fetuses with hyperechogenic kidneys were identified at a mean gestational age of 21 (range, 13-37) weeks. The majority of cases (97%) had bilateral hyperechogenic kidneys. In the 265 cases with available follow-up data, other associated renal tract abnormalities were identified prenatally in 36%, concomitant extrarenal structural abnormalities in 39% and abnormal karyotype in 15% of cases. Of the 316 included cases, 139 did not survive, including 105 terminations of pregnancy, five intrauterine deaths and 29 early neonatal deaths. Only 4.3% (6/139) of these fetuses had isolated hyperechogenic kidneys while 28.1% (39/139) had associated multiple renal tract abnormalities alongside hyperechogenic kidneys and over two-thirds (67.6%; 94/139) had concomitant extrarenal abnormalities. Of the 177 cases that survived beyond 1 month of age, outcome data were available in 126. Of these, based on the antenatal findings, 60 (47.6%) cases had isolated hyperechogenic kidneys, 56 (44.4%) had associated renal structural abnormalities and 10 (7.9%) had additional extrarenal abnormalities. Considering renal outcome alone, kidney function was abnormal in 13 (21.7%), 10 (17.9%) and 0 (0%) infants in these three groups, respectively, although concurrent pathology clearly affected global outcome in the more complex cases. Neonatal mortality of 1.6% was observed in the isolated renal hyperechogenicity group. The presence of oligohydramnios or abnormal renal volume was not associated significantly with abnormal renal function (odds ratio (OR), 2.32 (99% CI, 0.54-10.02) and OR, 0.74 (99% CI, 0.21-2.59), respectively) in this group.

CONCLUSIONS

Hyperechogenic kidneys are often complicated by associated renal tract and extrarenal abnormalities, aberrant karyotype and genetic disease, and these factors have a greater effect on overall outcome than does kidney echogenicity. The renal outcome of fetuses with isolated hyperechogenic kidneys is good generally, with over 70% of cases having normal renal function postpartum. Importantly, for prognostic counseling, all of the fetuses in this non-selected series with isolated hyperechogenic kidneys and normal amniotic fluid levels had normal renal outcome in infancy. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Etiologies and outcomes of prenatally diagnosed hyperechogenic kidneys

OBJECTIVES

To determine etiologies and outcomes of fetal hyperechogenic kidneys (HEK).

METHODS

We conducted a retrospective chart review of HEK in British Columbia (January 2013-December 2019) and literature review.

RESULTS

We identified 20 cases of HEK without other anomalies (isolated) in our provincial cohort, one was lost to follow-up. Eight had testable genetic etiologies (autosomal dominant polycystic kidney disease [ADPKD], autosomal recessive polycystic kidney disease [ARPKD], Bardet-Biedl syndrome [BBS], and HNF1B-related disorder). The remaining seven did not have an identifiable genetic etiology. Of cases without a genetic etiology with postnatal follow-up (n = 6) there were no abnormalities of blood pressure, creatinine/estimated glomerular filtration rate or urinalysis identified with follow-up from 2-71 months. We report 11 cases with extrarenal anomalies (nonisolated), with outcomes and etiologies. We identified 224 reported cases of isolated HEK in the literature. A potentially testable genetic etiology was found in 128/224 (57.1%). The neonatal death rate in those with testable etiologies was 17/128 (13.3%) compared to 2/96 (2.1%) when testable etiologies were excluded.

CONCLUSIONS

Genetic etiologies (ARPKD, ADPKD, BBS, HNF1B-related disorder, Beckwith-Wiedemann syndrome, tubular dysgenesis, familial nephroblastoma, and cytogenetic abnormalities) account for approximately half of prenatally isolated HEK; once excluded there are few neonatal deaths and short-term renal outcomes may be normal. There remains a paucity of knowledge about long-term renal outcomes.

[Kidney Cysts and Cystic Nephropathies in Children - A Consensus Guideline by 10 German Medical Societies]

This consensus-based guideline was developed by all relevant German pediatric medical societies. Ultrasound is the standard imaging modality for pre- and postnatal kidney cysts and should also exclude extrarenal manifestations in the abdomen and internal genital organs. MRI has selected indications. Suspicion of a cystic kidney disease should prompt consultation of a pediatric nephrologist. Prenatal management must be tailored to very different degrees of disease severity. After renal oligohydramnios, we recommend delivery in a perinatal center. Neonates should not be denied renal replacement therapy solely because of their age. Children with unilateral multicystic dysplastic kidney do not require routine further imaging or nephrectomy, but long-term nephrology follow-up (as do children with uni- or bilateral kidney hypo-/dysplasia with cysts). ARPKD (autosomal recessive polycystic kidney disease), nephronophthisis, Bardet-Biedl syndrome and HNF1B mutations cause relevant extrarenal disease and genetic testing is advisable. Children with tuberous sclerosis complex, tumor predisposition (e. g. von Hippel Lindau syndrome) or high risk of acquired kidney cysts should have regular ultrasounds. Even asymptomatic children of parents with ADPKD (autosomal dominant PKD) should be monitored for hypertension and proteinuria. Presymptomatic diagnostic ultrasound or genetic examination for ADPKD in minors should only be done after thorough counselling. Simple cysts are very rare in children and ADPKD in a parent should be excluded. Complex renal cysts require further investigation.

Management of delivery of a fetus with autosomal recessive polycystic kidney disease: a case report of abdominal dystocia and review of the literature

Background

Autosomal recessive renal polycystic kidney disease occurs in 1 in 20,000 live births. It is caused by mutations in both alleles of the PKHD1 gene. Management of delivery in cases of suspected autosomal recessive renal polycystic kidney disease is rarely discussed, and literature concerning abdominal dystocia is extremely scarce. We present a case of a patient with autosomal recessive renal polycystic kidney disease whose delivery was complicated by abdominal dystocia, and we discuss the factors that determined the route and timing of delivery.

Case presentation

A 23-year-old Caucasian woman, G2 P0, with a prior unremarkable pregnancy was referred to our tertiary center at 31 weeks of gestation because of severe oligoamnios (amniotic fluid index = 2) and hyperechogenic, dedifferentiated, and enlarged fetal kidneys. She had no other genitourinary anomaly. Fetal magnetic resonance imaging showed enlarged, hypersignal kidneys and severe pulmonary hypoplasia. We had a high suspicion of autosomal recessive renal polycystic kidney disease, and after discussion with our multidisciplinary team, the parents opted for conservative care. Ultrasound performed at 35 weeks of gestation showed a fetal estimated weight of 3550 g and an abdominal circumference of 377 mm, both above the 90th percentile. Because of the very rapid kidney growth and suspected risk of abdominal dystocia, we proposed induction of labor at 36 weeks of gestation after corticosteroid administration for fetal lung maturation. Vaginal delivery was complicated by abdominal dystocia, which resolved by continuing expulsive efforts and gentle fetal traction. A 3300-g (P50–90) male infant was born with Apgar scores of 1-7-7 at 1, 5, and 10 minutes, respectively, and arterial and venous umbilical cord pH values of 7.23–7.33. Continuous peritoneal dialysis was started at day 2 of life because of anuria. Currently, the infant is 1 year old and is waiting for kidney transplant that should be performed once he reaches 10 kg. Molecular analysis of PKHD1 performed on deoxyribonucleic acid (DNA) from the umbilical cord confirmed autosomal recessive renal polycystic kidney disease.

Conclusions

Management of delivery in cases of suspected autosomal recessive renal polycystic kidney disease needs to be discussed because of the risk of abdominal dystocia. The route and timing of delivery depend on the size of the fetal abdominal circumference and the gestational age. The rate of kidney growth must also be taken into account.

Prenatal detection of isolated bilateral hyperechogenic kidneys: Etiologies and outcomes

OBJECTIVES

To delineate the etiology and outcome of prenatally diagnosed isolated bilateral hyperechogenic kidneys (IBHK).

STUDY DESIGN

Pregnancies with IBHK on prenatal ultrasound identified and followed by us between January 1, 2000 and January 1, 2015 were evaluated regarding the etiology and outcome by evaluation of family history, targeted AR-PKD and AD-PKD DNA analysis, and microarray analysis, according to renal size and amniotic fluid volume.

RESULTS

Of the 52 identified cases, there were 34 cases with enlarged kidneys, 16 with normal size kidneys, and two with small kidneys. There were seven cases with AD-PKD, six inherited, and one with de novo causative variants in the PKD1 gene. Fifteen had AR-PKD, and microarray analysis showed two inherited findings: one with 17q12 deletion including the HNF1B/TCF2 gene inherited from asymptomatic mother and a duplication at 3p26.1 inherited from a healthy father. Of the remaining four cases, three cases had bilateral multicystic dysplastic kidneys, and one had unilateral renal agenesis.

CONCLUSION

Microarray analysis and mutation analysis for PKD1 and PKHD1 have an important contribution to the diagnostic investigation of IBHK and to the management of affected and future pregnancies. Poor outcome was associated with large hyperechoic kidneys with oligohydramnios.

Prenatal hyperechogenic kidneys in three cases of infantile hypercalcemia associated with SLC34A1 mutations

BACKGROUND

Prenatal diagnosis of hyperechogenic kidneys is associated with a wide range of etiologies and prognoses. The recent advances in fetal ultrasound associated with the development of next-generation sequencing for molecular analysis have enlarged the spectrum of etiologies, making antenatal diagnosis a very challenging discipline. Of the various known causes of hyperechogenic fetal kidneys, calcium and phosphate metabolism disorders represent a rare cause. An accurate diagnosis is crucial for providing appropriate genetic counseling and medical follow-up after birth.

METHODS

We report on three cases of fetal hyperechogenic kidneys corresponding to postnatal diagnosis of nephrocalcinosis. In all cases, antenatal ultrasound showed hyperechogenic kidneys of normal to large size from 22 gestational weeks, with a normal amount of amniotic fluid. Postnatal ultrasound follow-up showed nephrocalcinosis associated with hypercalcemia, hypercalciuria, elevated 1,25(OH)₂-vitamin D, and suppressed parathyroid hormone levels.

RESULTS

Molecular genetic analysis by next-generation sequencing performed after birth in the three newborns revealed biallelic pathogenic variants in the SLC34A1 gene, encoding the sodium/phosphate cotransporter type 2 (Npt2a), confirming the diagnosis of infantile hypercalcemia.

CONCLUSIONS

Nephrocalcinosis due to infantile hypercalcemia can be a cause of fetal hyperechogenic kidneys, which suggests early antenatal anomaly of calcium and phosphate metabolism. This entity should be considered in differential diagnosis. Postnatal follow-up of infants with hyperechogenic kidneys should include evaluation of calcium and phosphate metabolism.

[PKHD1 mutations in autosomal recessive polycystic kidney disease (ARPKD): Genotype-phenotype correlations from a series of 308 cases to improve prenatal counselling]

OBJECTIVES

ARPKD is a recessive rare disease due to PKHD1 mutation. The main objective of the study was to characterize the phenotypic variability according to the different types of PKHD1 mutations.

METHODS

This study was performed in 308 ARPKD patients with a genetic diagnosis from our genetic center. Related physicians provided minimal clinical and biological data.

RESULTS

Patients were divided into three genotypic groups: the first group (G1; n=65) consisted of patients with two truncating mutations, the second group (G2; n=117) of patients with one truncating and one non-truncating mutation, and the third group (G3; n=126) of patients with two non-truncating mutations. In the entire cohort, the outcomes consisted of 31% of pregnancy termination, 18% of neonatal deaths and 51% of patient survival after the neonatal period. The proportion of severe ARPKD (pregnancy termination or neonatal death) was significantly greater in G1: 94% versus 47% in G2 and 27% in G3 (P<0.001).

CONCLUSION

The presence of two truncating mutations in PKHD1 is associated with the most severe perinatal phenotype. However, the phenotypic variability observed in the other genotypic groups requires caution for prenatal counseling.

Causes of renal oligohydramnios: impact on prenatal counseling and postnatal outcome

The presence of renal oligohydramnios (ROH) in a fetus has been associated in the past with a poor prognosis for survival, although recent studies have shown that survival has improved considerably due to the advances in neonatology and pediatric nephrology. In an article recently published in Pediatric Nephrology, evaluation of a large series by Mehler and colleagues confirms the improved prognosis, showing a survival rate of 32 of 38 (84%). In addition, only 12 of 35 (34%) neonates required renal replacement therapy. In five of these 12 children the dialysis could be terminated after the neonatal period. This study has important implications on the decision-making process and counseling of families. While 37% of families of the study opted for termination of pregnancies, palliative care was chosen by 8% of the families, representing an important option when a decision cannot be made rapidly by affected families. A multidisciplinary approach is not only necessary in the active treatment of neonates with a history of ROH but also in antenatal counseling. In this regard future efforts should establish consensus on an ethical framework for the decision-making process in ROH.

Prenatal ultrasound, genotype, and outcome in a large cohort of prenatally affected patients with autosomal-recessive polycystic kidney disease and other hereditary cystic kidney diseases

PURPOSE

To investigate the sonographic and clinical genotype-phenotype correlations in autosomal recessive polycystic kidney disease (ARPKD) and other cystic kidney diseases (CKD) in a large cohort of prenatally detected fetuses with hereditary CKD.

METHODS

We retrospectively studied the clinical and diagnostic data of 398 patients referred with prenatal ultrasound findings suggestive of CKD between 1994 and 2010. Cases with confirmed hereditary CKD (n = 130) were analyzed as to their prenatal ultrasound findings, genotype, and possible predictors of clinical outcome.

RESULTS

ARPKD was most common in our non-representative sample. Truncating PKHD1 mutations led to a significantly reduced neonatal prognosis, with two such mutations being invariably lethal. Sonographically visible kidney cysts occurred in only 3% of ARPKD cases. Renal abnormalities in Meckel syndrome (MKS) appeared earlier than in ADPKD (19.6 ± 3.7 vs. 29.8 ± 5.1 GW) or ARPKD (19.6 ± 3.7 vs. 30.2 ± 1.2 GW). Additional CNS malformations were not found in ARPKD, but were highly sensitive for MKS. Pulmonary hypoplasia, oligo/anhydramnios (OAH), and kidney enlargement were associated with a significantly worse neonatal prognosis.

CONCLUSION

Genotype, sonographic signs of OAH, enlarged kidney size, and pulmonary hypoplasia can be useful predictors of neonatal survival. We propose sonographic morphological criteria for ARPKD, ADPKD, MKS, and renal cyst and diabetes syndrome (RCAD). We further propose a clinical diagnostic algorithm for differentiating cystic kidney diseases.

Renal tubular dysgenesis: antenatal ultrasound scanning and molecular investigations in a Saudi Arabian family

Autosomal recessive renal tubular dysgenesis (RTD) is a rare lethal disease affecting renal development before birth. RTD is manifested by anuria and severe hypotension resulting in oligohydramnios and birth defects known as Potter's syndrome. Homozygous or compound heterozygous mutations in genes encoding components of the renin-angiotensin system (ACE, AGT, AGTR1 and REN) have been reported to cause RTD. A consanguineous family with a history of multiple stillbirths was investigated using prenatal ultrasound and molecular genetic analysis of an affected foetus. Prenatal ultrasound scan suggested RTD, and a novel homozygous frameshift mutation c.299_300delAA (p.Lys100Serfs*4) in the REN gene was identified by whole-exome sequencing, which segregated with parental DNA samples. RTD remains a rare but important cause of prenatal and perinatal death and may present with antenatally hyperechogenic kidneys.

HNF1B-associated clinical phenotypes: the kidney and beyond

Mutations in HNF1B, the gene encoding hepatocyte nuclear factor 1β are the most commonly identified genetic cause of renal malformations. HNF1B was first identified as a disease gene for diabetes (MODY5) in 1997, and its involvement in renal disease was subsequently noted through clinical observations in pedigrees affected by MODY5. Since then, a whole spectrum of associated phenotypes have been reported, including genital malformations, autism, epilepsy, gout, hypomagnesaemia, primary hyperparathyroidism, liver and intestinal abnormalities and a rare form of kidney cancer. The most commonly identified mutation, in approximately 50 % of patients, is an entire gene deletion occurring in the context of a 17q12 chromosomal microdeletion that also includes several other genes. Some of the associated phenotypes, especially the neurologic ones, appear to occur only in the context of this microdeletion and thus may not be directly linked to HNF1B. Here we review the spectrum of associated phenotypes and discuss potential implications for clinical management.

Severe antenatally diagnosed renal disorders: background, prognosis and practical approach

Nowadays most renal disorders, especially urinary tract malformations and renal cystic disease, are diagnosed antenatally. In cases of severe bilateral disease, intrauterine renal dysfunction may lead to renal oligohydramnios (ROH), resulting in pulmonary hypoplasia which affects perinatal mortality and morbidity as well as the long-term outcome. However, some infants may only have mild pulmonary and renal disease, and advances in postnatal and dialysis treatment have resulted in improved short- and long-term outcome even in those infants with severe ROH. Here, we review the current state of knowledge and clinical experience of patients presenting antenatally with severe bilateral renal disorders and ROH. By addressing underlying mechanisms, intrauterine tools of diagnosis and treatment as well as published outcome data, we hope to improve antenatal counselling and postnatal care. KEY SUMMARY POINTS: 1. Nowadays most renal disorders are diagnosed antenatally, especially urinary tract malformations and renal cystic disease. 2. Severe kidney dysfunction may lead to renal oligohydramnios, which can cause pulmonary hypoplasia and is a risk factor of perinatal mortality and postnatal renal outcome. However, as considerable clinical heterogeneity is present, outcome predictions need to be treated with caution. 3. Advances in postnatal and dialysis treatment have resulted in improved short- and long-term outcomes even in infants with severe renal oligohydramnios. 4. A multidisciplinary approach with specialist input is required when counselling a family with an ROH-affected fetus as the decision-making process is very challenging.

Consensus expert recommendations for the diagnosis and management of autosomal recessive polycystic kidney disease: report of an international conference

Autosomal recessive polycystic kidney disease (ARPKD; MIM 263200) is a severe, typically early onset form of cystic disease that primarily involves the kidneys and biliary tract. Phenotypic expression and age at presentation can be quite variable1 . The incidence of ARPKD is 1 in 20,000 live births2 , and its pleotropic manifestations are potentially life-threatening. Optimal care requires proper surveillance to limit morbidity and mortality, knowledgeable approaches to diagnosis and treatment, and informed strategies to optimize quality of life. Clinical management therefore is ideally directed by multidisciplinary care teams consisting of perinatologists, neonatologists, nephrologists, hepatologists, geneticists, and behavioral specialists to coordinate patient care from the perinatal period to adulthood. In May 2013, an international team of 25 multidisciplinary specialists from the US, Canada, Germany, and the United Kingdom convened in Washington, DC, to review the literature published from 1990 to 2013 and to develop recommendations for diagnosis, surveillance, and clinical management. Identification of the gene PKHD1, and the significant advances in perinatal care, imaging, medical management, and behavioral therapies over the past decade, provide the foundational elements to define diagnostic criteria and establish clinical management guidelines as the first steps towards standardizing the clinical care for ARPKD patients. The key issues discussed included recommendations regarding perinatal interventions, diagnostic criteria, genetic testing, management of renal and biliary-associated morbidities, and behavioral assessment. The meeting was funded by the National Institutes of Health and an educational grant from the Polycystic Kidney Disease Foundation. Here we summarize the discussions and provide an updated set of diagnostic, surveillance, and management recommendations for optimizing the pediatric care of patients with ARPKD. Specialist care of ARPKD-related complications including dialysis, transplantation, and management of severe portal hypertension will be addressed in a subsequent report. Given the paucity of information regarding targeted therapies in ARPKD, this topic was not addressed in this conference.”

Fetal genitourinary imaging

The fetal urinary tract is routinely evaluated sonographically beginning in the first trimester with documentation of fetal bladder visualization. Fetal MR might be indicated to further clarify abnormalities found sonographically. The primary imaging modality for evaluation of the fetal kidney is US, which plays an important role in the detection of collecting system dilatation and parenchymal diseases that influence counseling and postnatal care. A commonly seen birth defect affecting the fetal kidney is pyelectasis. The significance of this finding has been extensively evaluated by a number of fetal imaging centers and will be presented in this review. Further topics of interest within the fetal genitourinary system include fetal renal parenchymal disorders and fetal bladder abnormalities. Characteristic imaging features, as well as developmental pathology and differential considerations, are discussed here.

Nonvisualization of fetal gallbladder increases the risk of cystic fibrosis

OBJECTIVE

The aim of our study is to evaluate the prevalence of cystic fibrosis (CF) in fetuses referred for genetic testing because of ultrasonographic sign (nonvisualized fetal gallbladder--NVFGB).

METHOD

We reviewed the results of CFTR gene analysis over the period 2002 to 2009 in all consecutive cases referred because of NVFGB in Western France. We correlated these data with the presence of a more classical ultrasonographic finding (fetal echogenic bowel - FEB).

RESULTS

Cystic fibrosis was diagnosed in 5 of the 37 fetuses with NVFGB (13.5%, 95% confidence interval (CI): [2.5%; 24.5%]) and in only 9 of the 229 other cases referred because of FEB (3.9%, 95% CI: [3.2%; 14.7%]). In our series, all CF-affected fetuses with NVFGB also had FEB. The risk of CF was 11.6-fold higher in fetuses with both indications (NVFGB + FEB) than in fetuses with isolated FEB (45.5% vs 3.9%, RR = 11.6, 95% CI: [4.7%; 28.8%], p = 0.0001). We also estimated that the residual risk of CF was less than 1 in 68 (1.5%) when a single mutation was identified in the fetus by our molecular protocol.

CONCLUSION

Ultrasonographic evidence of NVFGB is an additional risk factor for CF in cases with FEB.

Fetal surgery for severe lower urinary tract obstruction

Fetal interventions have been proposed for treatment of severe lower urinary tract obstruction (LUTO), as this condition is associated with high rates of perinatal mortality and postnatal renal impairment. The rationale for in utero treatment for those cases is based on the possibility of relieving the obstruction, improving the amniotic fluid volume, and preventing renal and bladder damage. Candidates for fetal intervention should be rigorously selected based on the confirmation of severe LUTO (dilated bladder and bilateral hydronephrosis), oligohydramnios or anyhydramnios and 'favorable' fetal urinalysis (dependent on gestational age). Nowadays there are two different therapeutic options with specific technical approaches. Vesico-amniotic shunting is an easier procedure, but with a higher frequency of related complications. Fetal cystoscopy can be used for diagnostic purpose and for treatment of posterior urethral valves, with suggestive advantage of allowing a more physiological release of the obstruction. According to the literature, estimated survival rates and postnatal normal renal function frequencies are approximately 40 and 50% after vesico-amniotic shunting and 75 and 65% after fetal cystoscopy, respectively.

Renal cystic diseases in children: new concepts

This review highlights the changes that have occurred in the general approach to cystic renal diseases in children. For instance, genetic mutations at the level of the primary cilia are considered as the origin of many renal cystic diseases. Furthermore, these diseases are now included in the spectrum of the hepato-renal fibrocystic diseases. Imaging plays an important role as it helps to detect and characterize many of the cystic diseases based on a detailed sonographic analysis. The diagnosis can be achieved during fetal life or after birth. Hyperechoic kidneys and/or renal cysts are the main sonographic signs leading to such diagnosis. US is able to differentiate between recessive and dominant polycystic kidney diseases, hepatocyte nuclear factor 1 Beta mutation, glomerulocystic kidneys and nephronophtisis. MR imaging can, in selected cases, provide additional information including the progressive associated hepatic changes.

[Management of antenatal fetal abdominal tumors. Clues for the diagnosis of a congenital mesoblastic nephroma]

The prenatal diagnosis of abdominal mass poses the problem of its origin. Renal tumors are rarer than neuroblastoma but they are most often congenital mesoblastic nephroma. The congenital mesoblastic nephroma has a good forecast in spite of a sonographic impressive aspect. MRI can help to locate tumor but cannot tell difference between the different kinds of renal tumor. Prenatal forecast is especially linked with hydramnios and hydrops fetalis. Histolological study of the tumor is important for the prognosis. Two morphological subtypes are currently distinguished: the classic type with a good forecast and the atypical or cellular type. Distant metastases have been related only to the cellular form but especially in infants aged more than 3 months and never in the newborns. The diagnosis of the tumor does not change the mode of delivery except in case of an important volume. Complications are searched during the first days of life: hypertension, hypercalcemia, vomiting, hyperreninemia. Radical nephrectomy is performed after the end of the first week. In case of a classic form, the healing is always obtained. In case of cellular form, distant metastases are searched. In any rate, the follow-up is recommended until the end of the growth.

Anomalies of the TCF2 gene are the main cause of fetal bilateral hyperechogenic kidneys

Prenatal discovery of fetal bilateral hyperechogenic kidneys is very stressful for pregnant women and their family, and accurate diagnosis of the cause of the moderate forms of this pathology is very difficult. Hepatocyte nuclear factor-1beta that is encoded by the TCF2 gene is involved in the embryonic development of the kidneys. Sixty-two pregnancies with fetal bilateral hyperechogenic kidneys including 25 fetuses with inaccurate diagnosis were studied. TCF2 gene anomalies were detected in 18 (29%) of these 62 patients, and 15 of these 18 patients presented a complete heterozygous deletion of the TCF2 gene. Family screening revealed de novo TCF2 anomalies in more than half of the patients. TCF2 anomalies were associated with normal amniotic fluid volume and normal-sized kidneys between -2 and +2 SD in all patients except for two sisters. Antenatal cysts were detected in 11 of 18 patients, unilaterally in eight of 11. After birth, cysts appeared during the first year (17 of 18), and in patients with antenatal cysts, the number increased and developed bilaterally with decreased renal growth. In these 18 patients, the GFR decreased with longer follow-up and was lower in patients with solitary functioning dysplastic kidney. Heterozygous deletion of the TCF2 gene is an important cause of fetal hyperechogenic kidneys in this study and showed to be linked with early disease expression. The renal phenotype and the postnatal evolution were extremely variable and need a prospective long-term follow-up. Extrarenal manifestations are frequent in TCF2-linked pathologies. Therefore, prenatal counseling and follow-up should be multidisciplinary.

Perinatal assessment of hereditary cystic renal diseases: the contribution of sonography

The aims of this review article were to clarify the steps that may lead to a proper diagnosis of fetal and neonatal renal cystic diseases. All the hereditary cystic diseases are reviewed and a classification is proposed. The various sonographic patterns that can be used to ascertain the diagnosis are also reviewed. Finally, tables with differential diagnoses are presented to help the reader in the work-up of such pathologies.

Fetal hyperechogenic kidney with normal amniotic fluid volume: a diagnostic dilemma

OBJECTIVE

To determine the prognostic value of sonographically detected fetal hyperechogenic kidneys with normal amniotic fluid volume.

METHODS

Seven cases of hyperechogenic fetal kidneys were identified by sonography over a 7-year period (1996--2002). Increased renal echogenicity was diagnosed when the renal parenchyma was of greater echogenicity than adjacent liver tissue. Amniotic fluid volume was measured by the semiquantitative sonographic technique known as the amniotic fluid index (AFI).

RESULTS

Three of the live-born infants had autosomal dominant polycystic kidney disease and one had autosomal recessive polycystic kidney. In the remainder, autopsy study revealed multifocal renal dysplasia in two cases and normal kidneys in one.

CONCLUSIONS

Increased renal echogenicity with normal amniotic fluid volume in a fetus without other anomalies is a difficult diagnostic dilemma. Although it is usually indicative of renal parenchymal disease with possible renal failure after birth or in early childhood, in some cases, it represents a normal variant. .

Prenatal sonographic patterns in autosomal dominant polycystic kidney disease: a multicenter study

OBJECTIVE

To determine whether a specific prenatal sonographic pattern can be identified for autosomal dominant polycystic kidney disease (ADPKD) and if so whether it would be helpful in orienting complementary analysis, properly counseling parents and adapting pregnancy management.

METHODS

A retrospective multicenter study was conducted in four prenatal diagnostic centers. The records of fetuses with a prenatal ultrasound examination revealing abnormal kidneys and with a final diagnosis of ADPKD were analyzed. Ultrasound analysis included: amount of amniotic fluid, bladder size, renal length, presence or absence of renal cysts and size of renal pelves, and was focused on parenchyma echogenicity and status of corticomedullary differentiation. Postnatal follow-up was reviewed.

RESULTS

Of the 27 patients included in the study, 25 had hyperechogenic renal cortex and 20 had hypoechogenic medulla resulting in increased corticomedullary differentiation (CMD). In six cases, the medulla was hyperechogenic leading to absent or decreased CMD. One patient had normal cortical echogenicity and CMD. Renal cysts were present during the prenatal period in four patients (at 22 weeks in one case and after 30 weeks in three cases). In 12 patients, the cysts appeared after birth (within the first 6 months of postnatal life in 10 cases and by the age of 1 year in two cases). Elevated blood pressure was observed in only two cases and moderate chronic renal failure in one case.

CONCLUSION

We have described the sonographic presentation in fetuses with ADPKD: moderately enlarged hyperechogenic kidneys with increased CMD. Although not specific to ADPKD, these findings should prompt familial screening. Other prenatal sonographic features (absent or decreased CMD and cortical cysts) are less frequent.