Size and volume charts of fetal kidney, renal pelvis and adrenal gland

Standardised and structured reporting in fetal magnetic resonance imaging: recommendations from the Fetal Task Force of the European Society of Paediatric Radiology

Over the last decades, magnetic resonance imaging (MRI) has emerged as a valuable adjunct to prenatal ultrasound for evaluating fetal malformations. Several radiological societies advocate for standardised and structured reporting practices to enhance the uniformity of imaging language. Compared to narrative formats, standardised and structured reports offer enhanced content quality, minimise reader variability, have the potential to save reporting time, and streamline the communication between specialists by employing a shared lexicon. Structured reporting holds promise for mitigating medico-legal liability, while also facilitating rigorous scientific data analyses and the development of standardised databases. While structured reporting templates for fetal MRI are already in use in some centres, specific recommendations and/or guidelines from international societies are scarce in the literature. The purpose of this paper is to propose a standardised and structured reporting template for fetal MRI to assist radiologists, particularly those with less experience, in delivering systematic reports. Additionally, the paper aims to offer an overview of the anatomical structures that necessitate reporting and the prevalent normative values for fetal biometrics found in current literature.

Predicting clinically significant events in children with ureteropelvic junction obstruction

Introduction

Ureteropelvic junction obstruction (UPJO) syndrome is one of the most common causes of neonatal hydronephrosis. Management varies from simple monitoring to surgical intervention, with indications differing between institutions. A consensus of 8 societies recently described a new Urinary Tract Dilation (UTD) classification which aims to standardize ultrasound description of hydronephrosis, but which is also supposed to have predictive value in children with hydronephrosis. Our aim was to compare, in a monocentric prospective cohort of children with UPJO, the ability of UTD to predict the occurrence of a clinically significant event within the first year of life, as compared to anteroposterior diameter of the renal pelvis (APD).

Study design

We used a preexisting cohort of children followed in a prospective study on UPJO. A pediatric radiologist, blinded to the children's outcome, classified the last antenatal ultrasound and postnatal ultrasound according to the UTD-A and UTD-P classification. He also confirmed the APD-A and APD-P measures. We defined a clinically significant event as being: increased pelvic dilation (>5 mm) and/or the presence of a febrile urinary tract infection (fUTI) and/or impaired renal function on initial nuclear scan (<40%). We performed a ROC-AUC curve and Random Forest (RF) analysis to compare the ability of the APD-A, APD-P, UTD-A and UTD-P scores to predict a clinically significant event.

Results

The cohort included 28 children. Clinically significant events were noted in 20 out of 28 patients: 13 children presented an increase >5 mm in dilation, 6 presented an episode of fUTI and 9 had impaired function of the affected kidney. APD-A was the most effective individual criterion for predicting the occurrence of a significant clinical event (AUC = 0.867).

Conclusion

In our series, for children with UPJO, the most significant marker was prenatal APD >15 mm to predict an increase in dilation >5 mm.

High resolution dynamic ultrasound atlas of embryonic and fetal development of the common marmoset

PURPOSE

The common marmoset (Callithrix jacchus) provides an ideal model to study early development of primates, and an in vivo platform to validate conclusions from in vitro studies of human embryos and embryo models. Currently, however, no established staging atlas of marmoset embryonic development exists. Using high-resolution, longitudinal ultrasound scans on live pregnant marmosets, we present the first dynamic in vivo imaging of entire primate gestation beginning with attachment until the last day before birth.

METHODS

Our study unveils the first dynamic images of an in vivo attached mammalian embryo developing in utero, and the intricacies of the delayed development period unique to the common marmoset amongst primates, revealing a window for somatic interventions.

RESULTS

Established obstetric and embryologic measurements for each scan were used comparatively with the standardized Carnegie staging of human development to highlight similarities and differences. Our study also allows for tracking the development of major organs. We focus on the ontogeny of the primate heart and brain. Finally, input ultrasound images were used to train deep neural networks to accurately determine the gestational age. All our ultrasounds and staging data recording are posted online so that the atlas can be used as a community resource toward monitoring and managing marmoset breeding colonies.

CONCLUSION

The temporal and spatial resolution of ultrasound achieved in this study demonstrates the promise of noninvasive imaging in the marmoset for the in vivo study of primate-specific aspects of embryonic and fetal development.

Prenatal ultrasound in fetuses with polycystic kidney appearance - expanding the diagnostic algorithm

PURPOSE

Report on the diagnosis of prenatally detected fetal kidneys with bilateral polycystic appearance in a single center between 1999 and 2020 with special focus on renal morphology and biometry, amniotic fluid and extrarenal findings and proposal for an diagnostic algorithm.

METHODS

Retrospective observational study including pregnancies with prenatally detected kidneys with bilateral polycystic appearance (n = 98). Cases and outcomes were compared according to prenatal findings with special focus on renal morphology, amount of amniotic fluid, and presence of extrarenal abnormalities.

RESULTS

Most frequent diagnoses were autosomal recessive polycystic kidney disease (ARPKD, 53.1%), Meckel-Gruber syndrome (MKS, 17.3%) and autosomal dominant polycystic kidney disease (ADPKD, 8.2%). Other diagnoses included: Joubert-, Jeune-, McKusick-Kaufman- and Bardet-Biedl syndrome, overgrowth syndromes, Mainzer-Saldino syndrome and renal tubular dysgenesis. Renal abnormalities most frequently observed were hyperechogenic parenchyma, kidney enlargement, changes of corticomedullary differentiation and cystic changes of various degree. Oligo- and anhydramnios were mainly seen in ARPKD, RTD and second-trimester MKS. Extrarenal findings included skeletal (35.7%) and cardiac (34.7%) abnormalities as well as abnormalities of the central nervous system (27.6%).

CONCLUSION

Gestational age at manifestation, kidney size, visibility of cysts, echogenicity, amniotic fluid volume, and the presence of associated extrarenal malformations allow to differentiate between the most frequent underlying diseases presenting with bilateral polycystic kidneys on prenatal ultrasound by following a diagnostic algorithm.

Fetal adrenal gland size and umbilical artery Doppler in growth-restricted fetuses

OBJECTIVES

In fetal growth restriction (FGR), Doppler ultrasound is the most important method for the detection and management. However, additional parameters are needed to improve the distinction between constitutionally small fetuses and fetuses affected by FGR.

METHODS

A total of 445 singleton pregnancies between 23 and 40 weeks of gestation were included in our retrospective study, of which 67 with FGR and 378 normal fetuses. A 2D-plane of the fetal adrenal gland was obtained and the adrenal gland ratio was measured. Spearman's correlation coefficient was calculated to assess the association of fetal Doppler and adrenal gland ratio with outcome parameters. Logistic regression analysis was performed to assess the statistical significance of "PI of the umbilical artery" and "adrenal gland ratio" as prognostic factors for intrauterine growth restriction (IUGR).

RESULTS

PI of the umbilical artery was shown to correlate with outcome parameters (WG_Delivery: r=-0.125, p=0.008; birth weight: r=-0.268, p<0.001; birth weight centile: r=-0.248, p<0.001; APGAR at 5 min: r=-0.117, p=0.014). Adrenal gland ratio showed no correlation with any of the outcome parameters. In logistic regression however, both PI of the umbilical artery and the adrenal ratio were shown to be significantly associated with fetal IUGR. When combining the two parameters, predictive value was superior to the predictive value of each individual parameter (AUC 0.738 [95% CI 0.670; 0.806]).

CONCLUSIONS

The adrenal gland ratio can be a useful addition to Doppler ultrasound when it comes to the detection of fetal FGR. Prospective studies are needed to establish references ranges and cut-off values for clinical decision-making.

Relationship among anogenital distance, adrenal gland volume, and penile length and width at 22-36 weeks of pregnancy

OBJECTIVES

The subject of current work was to determine the relationship of fetal ultrasonographic biomarkers, including anogenital distance (AGD), adrenal gland volume, and penile length and width in mothers with male fetuses at 22-36 weeks of gestation for the assessment of the effect of fetal adrenal gland producing androgens on the male anogenital structures that are exposed to androgen effects as anogenital region and penis.

METHODS

This study is a prospective cross-sectional study conducted in our hospital's outpatient perinatal care unit. One hundred and seventy pregnant women with a male fetus aged 22-36 weeks of gestation were included in the study. The fetal adrenal gland length, width, and depth for the calculation of adrenal volume, AGD, and penile length and width were measured for each participant. The Pearson coefficients were calculated to assess the correlation among these parameters.

RESULTS

The adrenal gland volume had a meaningful, positive moderate relationship with both the AGD (r=0.60) and penile length and width (r=0.57 and r=0.59, respectively; p<0.001). The AGD had a positive, strong correlation with the penile length and width (r=0.74 and r=0.76, respectively; p<0.001).

CONCLUSIONS

The fetal adrenal gland as one of the androgen sources of the fetus is an influencer of the development of the anogenital and penile region. The findings of the current study support that the adrenal gland considerably affects the masculinization of male fetuses, since there were remarkable correlations among the AGD, adrenal gland volume, and penile length and width.

Development of the Urinary Tract in Fetal Rats: A Micro-CT Study

INTRODUCTION

 Micro-computed tomography (micro-CT) is an established tool to study fetal development in rodents. This study aimed to use micro-CT imaging to visualize the development of the urinary tract in fetal rats.

MATERIALS AND METHODS

 Fetal rats from embryonic day (ED) 15, ED17, ED19, ED21, and N0 (newborn) (n = 6 per group; 3 males) were fixed and desiccated using the "critical point" technique. We utilized the micro-CT system (SkyScan) and analyzed the resulting scans with CTAn, DataViewer, and ImageJ to visualize the morphology and quantify the volumes of kidney, bladder, adrenal gland, as well as length of the ureter.

RESULTS

 High-resolution micro-CT showed continuous growth of both kidneys from ED15 to N0, with the highest increase between ED19 and ED21. The length of the ureter increased from ED15 to ED21 and remained stable until birth. The volume of the bladder steadily increased from ED15 to N0.In females, a statistically higher volume of the adrenal gland on ED21 was observed, whereas no sex-specific differences were seen for kidney, ureter, and bladder development.

CONCLUSION

 Micro-CT depicts an excellent tool to study urinary tract development in the fetal and neonatal rat. It enables the metric quantification of longitudinal anatomic changes in high definition without previous destructive tissue preparation. The present study revealed sex-specific differences of the adrenal gland development and provides comprehensive data for the understanding of fetal urinary tract development, inspiring future research on congenital urological malformations.

Kidney Volume Growth and Kidney Function of en bloc Pediatric Kidney Transplants: A Case Series

Rationale & Objective

Kidney transplant is a mainstay of kidney replacement therapy. Given a continued shortage of organs, pediatric en bloc kidney transplants may have substantial utility. We present our long-term experience with en bloc transplants from donors aged 3 to 60 months, including changes in kidney function and kidney volume over time as well as biopsy findings.

Study Design

Case series.

Setting & Participants

Medical records from a single academic medical center were reviewed. Aggregate serial volumes of 22 en bloc kidney allografts from 2010 to 2017 were assessed at the time of transplant and during follow-up. Estimated glomerular filtration rates (eGFR) were described at 3 months after transplant (baseline) as well as over the ensuing 3 years. Interstitial fibrosis, a finding determined by histopathologic review, which results from an accumulation of collagen that is produced from mediators produced from complex interaction of multiple inflammatory cells, was assessed on 20 protocol biopsies obtained from 6 patients, of which 4 patients had 4 biopsies and 2 patients had 1 biopsy.

Results

Kidney volume was obtained from 51 ultrasound studies performed up to 74 months after transplant. Kidney volume generally increased and eGFR rose over time after the transplant, with 23% patients achieving an eGFR of >75 mL/min/1.73 m² at 3 months posttransplant. The remainder achieved an eGFR >75 mL/min/1.73 m² over the ensuing 3 years. Interstitial fibrosis noted on biopsies appeared to foreshadow an eventual reduction in kidney volume.

Limitations

Retrospective study, possible selection bias, single-center experience.

Conclusions

The kidney en bloc allografts increased in size after transplantation, with associated improved kidney function. Chronic damage to the graft, from interstitial fibrosis and tubular atrophy, resulted in long-term reduction in kidney volume.

Proposal for Practical Approach in Prenatal Diagnosis of Beckwith–Wiedemann Syndrome and Review of the Literature

Background: Beckwith–Wiedemann syndrome (BWS) is a phenotypically and genetically heterogeneous disorder associated with epigenetic/genetic aberrations on chromosome 11p15.4p15.5. There is no consensus criterion for prenatal diagnosis of BWS. Methods: Three BWS patients with their clinical histories, prenatal ultrasonographic features, and results of molecular diagnosis were presented. Likewise, by incorporating the findings of our cases and literature review, the phenotypic spectrum and genotype–phenotype correlations of fetal BWS were summarized, and a practical approach in prenatal diagnosis of BWS was proposed. Results: A total of 166 BWS cases with prenatal features were included for analysis. Common fetal features include abdominal wall defects (42.8%), polyhydramnios (33.1%), and macrosomia (32.5%). Molecular pathologies include methylation changes in imprinting control region 1 and 2 (ICR1 and ICR2), paternal uniparental disomy of chromosome 11p15.5, copy number change involving 11p15, etc. Some genotype–phenotype correlations were observed. However, the broad phenotypic spectrum but limited features manifested by affected fetuses rendering ultrasonographic diagnosis not easy. Conclusions: Molecular tests are used for prenatal diagnosis of BWS suspected by ultrasonography. Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) is recommended as the first-line molecular tool because it simultaneously detects ICR1/ICR2 methylation statuses and copy numbers that solve the majority of clinical cases in the prenatal scenario.

2021 update on the urinary tract dilation (UTD) classification system: clarifications, review of the literature, and practical suggestions

In 2014, a multidisciplinary consensus on the classification of pre- and postnatal urinary tract dilation (UTD classification) was developed. Its goal was to provide a standardized system for evaluating and reporting urinary tract dilation both in the prenatal and postnatal periods. In this review, we summarize insights learned from the implementation of the UTD classification system since its inception, providing clarifications on common points of confusion. In addition, we review current literature in the clinical validation of the UTD classification system to provide credence for its use in managing fetuses and children with urinary tract dilation.

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.

Urinary Cystatin-C, a marker to assess and monitor neonatal kidney maturation and function: validation in twins

BACKGROUND

Nephrogenesis is a complex process of nephron formation and maturation that can be compromised by preterm delivery and intrauterine growth restriction. This study aimed to evaluate and compare urinary Cys-C levels with renal volume in a cohort of preterm and term twins, adequate for gestational age or intrauterine growth restricted, to investigate their values in different conditions of nephrogenesis.

METHODS

The study was performed on twins at 30-40 days of postnatal corrected age: renal volumes were measured by 3D ultrasound technology and urine samples were analyzed for Cystatin-C. A follow-up was performed by Cystatin-C.

RESULTS

Renal volumes in preterm and intrauterine growth-restricted twins showed values significantly lower than those observed in term twins and were inversely correlated to urinary Cystatin-C levels. During the follow-up, intrauterine growth-restricted twins showed amplified levels of urinary Cystatin-C; in contrast, invariable or decreased levels were observed in adequate for gestational age twins.

CONCLUSIONS

Urinary Cystatin-C, evaluated when intrauterine/extrauterine nephrogenesis could be considered completed, concurrently with renal volume assessment can improve the identification of neonates with initial kidney impairment. Its potential value as a useful marker in monitoring physiological/pathological renal conditions could be considered, mainly for neonates at elevated risk of developing long-term renal diseases.

IMPACT

Urinary Cys-C levels are inversely correlated to renal volumes and reflect nephrogenesis conditions. No data in literature are reported regarding: (a) the concurrent assessment of renal volumes and urinary levels of Cystatin-C in preterm and term twins with different conditions of gestational life, i.e., AGA and IUGR and (b) the follow-up of IUGR and preterm neonates using the urinary Cys-C determination. The variations of urinary Cys-C levels, observed in the follow-up of preterm and/or IUGR neonates, support the usefulness of monitoring those neonates with altered nephrogenesis, who are later at risk for renal impairment and for long-term renal diseases.

Longitudinal adrenal gland measurements and growth trajectories as risk markers for late preterm delivery

BACKGROUND

The fetal adrenal gland receives rising awareness as a predictor of spontaneous preterm birth. We hereby provide longitudinal growth assessments of the fetal adrenal gland in a low risk population with an additional focus on trajectories in fetuses born preterm.

METHODS

Fetal adrenal gland was assessed via transabdominal ultrasound at gestational weeks (gw) 24-26, 28-30, and 34-36 in a low-risk pregnancy cohort. Longitudinal trajectories of the total gland and the mark (so called fetal zone) as well as ratio of fetal zone width/ total widths (w/W) were analyzed using repeated ANOVA analyses. To compare trajectories of the ratio w/W for preterm and term fetuses respectively, as well as women with and without clinical signs of preterm labor, the propensity score method was applied.

RESULTS

Fetal zone width increased over the course of pregnancy (p < 0.0001), while the ratio w/W decreased (p < 0.0001) (n = 327). Comparing the trajectories of the ratio w/W in fetuses born preterm (n = 11) with propensity-score matched term born fetuses (n = 22), a decrease between gw 24-26 and 28-30 was observed in both groups, which continued to decrease for the term born fetuses. However, in preterm born fetuses, the ratio increased above the term born values at gw 34-36.

CONCLUSION

Our study provides for the first time longitudinal growth data on the fetal adrenal gland and supports the hypothesis that fetal zone enlargement is associated with preterm birth which could play an important role in risk-prediction.

Fetal adrenal gland: Total gland volume and fetal zone to total gland ratio as markers of small for gestational age

PURPOSE

Fetal adrenal gland changes have previously been investigated as novel markers of preterm labor and small for gestational age (SGA) fetuses. We aimed to compare the fetal adrenal gland parameters in SGA and appropriate for gestational age (AGA) fetuses.

METHODS

A prospective cohort study was conducted on SGA fetuses with estimated fetal weight (EFW) ≤10th centile and AGA (EFW >10th centile) at 17 to 34 weeks gestation. Fetal adrenal total gland volume (TGV), TGV corrected for EFW (cTGV), fetal zone volume (FZV), FZV corrected for EFW (cFZV), and FZV:TGV ratio were compared and correlated with gestational age and EFW. Receiver operator curves assessed FZV:TGV ratio, cTGV, and cFZV in detecting SGA.

RESULTS

Ultrasound examinations from 103 AGA and 50 SGA fetuses showed that (a) SGA fetuses had higher TGV (P = .002), FZV (P = .001), and FZV:TGV (P = .036) compared to AGA fetuses; (b) fetal adrenal TGV, FZV, cFZV, and FZV:TGV increase with advancing gestational age and EFW while cTGV does not; (c) Fetal adrenal changes in cTGV, cFZV, and FZV:TGV have ability to differentiate SGA; (d) FZV:TGV ratio 10 and 25 may be used to identify or exclude SGA in antenatally suspected SGA.

CONCLUSIONS

We investigated the concept that SGA fetuses have measurable changes to the adrenal gland. We have shown that fetal TGV, TGV, and FZV:TGV ratio show differences between AGA and SGA with TGV remaining significant after accounting for GA at scan. These findings may be useful as potential biomarkers for diagnosing or excluding SGA.

Deformable Slice-to-Volume Registration for Motion Correction of Fetal Body and Placenta MRI

In in-utero MRI, motion correction for fetal body and placenta poses a particular challenge due to the presence of local non-rigid transformations of organs caused by bending and stretching. The existing slice-to-volume registration (SVR) reconstruction methods are widely employed for motion correction of fetal brain that undergoes only rigid transformation. However, for reconstruction of fetal body and placenta, rigid registration cannot resolve the issue of misregistrations due to deformable motion, resulting in degradation of features in the reconstructed volume. We propose a Deformable SVR (DSVR), a novel approach for non-rigid motion correction of fetal MRI based on a hierarchical deformable SVR scheme to allow high resolution reconstruction of the fetal body and placenta. Additionally, a robust scheme for structure-based rejection of outliers minimises the impact of registration errors. The improved performance of DSVR in comparison to SVR and patch-to-volume registration (PVR) methods is quantitatively demonstrated in simulated experiments and 20 fetal MRI datasets from 28-31 weeks gestational age (GA) range with varying degree of motion corruption. In addition, we present qualitative evaluation of 100 fetal body cases from 20-34 weeks GA range.

Normal size of the fetal adrenal gland on prenatal magnetic resonance imaging

BACKGROUND

The adrenal gland plays a vital role in fetal growth. Many disease states such as congenital adrenal hyperplasia, hemorrhage and tumors can lead to morphological changes in the gland. Ultrasound measurements of normal adrenal sizes in the fetus reported in the literature have shown a trend of increasing size with gestational age. There is no literature available on standard fetal adrenal sizes or detailed appearance by fetal MRI.

OBJECTIVE

The purpose of this study was to provide MR data on the size and signal characteristics of the fetal adrenal gland throughout the second and third trimesters.

MATERIALS AND METHODS

In this retrospective review, we selected 185 prenatal MRIs obtained from Jan. 1, 2014, to May 31, 2017, with normal abdominal findings for inclusion. The adrenal glands were identified in coronal, sagittal or axial T2-W planes and coronal T1-W plane when available. We measured the length and thickness of the medial and lateral limbs of the right and left adrenal glands and recorded signal intensity on T1-W and T2-W sequences, gender and gestational age in each case.

RESULTS

The gestational age (GA) ranged 18-37 weeks. Visibility of the adrenal glands on T2-W images was high (90.3-97.2%) up to 30 weeks of GA but declined afterward (47.5-62.2% at 31-37 weeks). Visibility on T1-W images increased with GA, ranging from 21.4% visibility at 18-22 weeks and increasing to 40% at 35-37 weeks. Mean lengths of the adrenal gland limbs steadily increased from 8.2 mm at 18-22 weeks to 11.0 mm at 35-37 weeks. In the second trimester, adrenal glands were low in signal intensity on T2-W images and were surrounded by hyperintense perirenal fatty tissue. In the third trimester, the glands became less distinct, with increasing signal and obliteration of perirenal tissue. The glands were moderately hyperintense on T1-W images throughout pregnancy, with increasing visibility as pregnancy progressed.

CONCLUSION

Normal sizes and signal intensities for adrenal glands are reported. Visibility of adrenal glands on T2-W images was 90.3-97.2% up to 30 weeks but declined thereafter. Visibility on T1-W images increased in the third trimester. Adrenal gland sizes increased with gestational age.

Fetal kidney charts of a novel measurement of the renal parenchymal thickness to evaluate fetal kidney growth and potential function

OBJECTIVE

The objective of this study was to develop new standard growth charts for fetal renal parenchymal thickness, length, and volume to define normal ranges for use in clinical practice and to assess the reliability of these measurements.

METHODS

This was a prospective, longitudinal study of 72 low-risk singleton pregnancies undergoing serial ultrasound examinations at least every four weeks. Multiple renal measurements were performed on both kidneys at each scan. The renal parenchymal thickness was measured in the mid-sagittal plane. Standard charts were developed and the intra and interobserver reliability for the renal measurements was analysed.

RESULTS

Standard charts were developed for fetal renal parenchymal thickness, length, and volume.

CONCLUSION

We present novel charts, which demonstrate the growth of the fetal renal parenchyma during pregnancy. They will be useful in clinical practice to identify any alterations from these normal ranges, which may be an important criterion for assisting prenatal diagnosis of renal pathologies and future studies in the prediction of kidney function.

Fetal Physiologically Based Pharmacokinetic Models: Systems Information on the Growth and Composition of Fetal Organs

BACKGROUND

The growth of fetal organs is a dynamic process involving considerable changes in the anatomical and physiological parameters that can alter fetal exposure to xenobiotics in utero. Physiologically based pharmacokinetic models can be used to predict the fetal exposure as time-varying parameters can easily be incorporated.

OBJECTIVE

The objective of this study was to collate, analyse and integrate the available time-varying parameters needed for the physiologically based pharmacokinetic modelling of xenobiotic kinetics in a fetal population.

METHODS

We performed a comprehensive literature search on the physiological development of fetal organs. Data were carefully assessed, integrated and a meta-analysis was performed to establish growth trends with fetal age and weight. Algorithms and models were generated to describe the growth of these parameter values as functions of age and/or weight.

RESULTS

Fetal physiologically based pharmacokinetic parameters, including the size of the heart, liver, brain, kidneys, lungs, spleen, muscles, pancreas, skin, bones, adrenal and thyroid glands, thymus, gut and gonads were quantified as a function of fetal age and weight. Variability around the means of these parameters at different fetal ages was also reported. The growth of the investigated parameters was not consistent (with respect to direction and monotonicity).

CONCLUSION

Despite the limitations identified in the availability of some values, the data presented in this article provide a unique resource for age-dependent organ size and composition parameters needed for fetal physiologically based pharmacokinetic modelling. This will facilitate the application of physiologically based pharmacokinetic models during drug development and in the risk assessment of environmental chemicals and following maternally administered drugs or unintended exposure to environmental toxicants in this population.

Prenatal Diagnosis of Autosomal Recessive Renal Tubular Dysgenesis with Anhydramnios Caused by a Mutation in the AGT Gene

Autosomal recessive renal tubular dysgenesis (ARRTD) is a rare and lethal disorder that causes stillbirth or early neonatal death. Most of the reported cases are diagnosed postnatally by a histopathological hallmark of the absence or paucity of differentiated proximal tubules in kidneys. Prenatal diagnosis of ARRTD is challenging because only a few fetal features (e.g., oligohydramnios/anhydramnios, anuria) are associated with this condition. In this study, we report a fetus with ARRTD, which showed anhydramnios and invisible urinary bladder since the second trimester, followed by growth restriction and reversed end diastolic flow in the middle cerebral artery (MCA-REDF). No morphological anomaly was detected on the fetal kidneys during an ultrasound scan. The baby died of refractory hypotension the day after their birth. Genetic analysis of genes that are involved in the renin-angiotensin-aldosterone system (RAAS), which are the known genetic causes of ARRTD, identified a novel, biparental-origin homozygous c.857-619_1269+243delinsTTGCCTTGC mutation in the AGT gene. The mutation is considered as pathogenic because it is cosegregated with ARRTD and detected in other unrelated ARRTD families. Our findings link the fetal ultrasound manifestations to the ARRTD, highlighting clues that are useful for prenatal diagnosis, which warrants confirmatory genotyping of the RAAS genes including oligohydramnios/anhydramnios, anuria (absent filling of a fetal urinary bladder), MCA-REDF, and a morphologically normal kidney.

Fetal adrenal gland size and the ability to predict spontaneous term labor

OBJECTIVE

The objective of this study was to evaluate whether ultrasound measured fetal adrenal gland size can be a predictor of spontaneous term labor.

STUDY DESIGN

This study was a diagnostic test accuracy study using a prospective cohort design evaluating the ability of 2-dimensional ultrasound measurement of fetal adrenal gland total length, total width, fetal zone length and fetal zone width in women in the third trimester to predict the primary outcome of spontaneous term labor. Secondary outcomes were vaginal delivery, length of labor, and maternal and neonatal morbidities.

RESULTS

Of 43 patients recruited, 3 were excluded. 11 (25.6%) presented in spontaneous labor and 29 (67.4%) underwent induction of labor. Patient demographics were similar for all included except for admission cervical exam and oxytocin use. A receiver operative curve was created to assess test predictability. Weighted width of fetal adrenal gland was the best predictor of spontaneous labor amongst variables measured with an area under the curve of 0.674, p = 0.93. w/W ≥ 0.41 had a sensitivity of 91.0%, specificity of 44.8%, positive predictive value of 38.5% and a negative predictive value of 92.3%. Maternal and neonatal morbidities were not different between the spontaneous labor group and the induction of labor group.

CONCLUSION

Ultrasound measured fetal w/W was moderately predictive of spontaneous labor.

Reference ranges for ultrasound measurements of fetal kidneys in a cohort of low-risk pregnant women

PURPOSE

Alterations in renal dimensions may be an early manifestation of deviation from normality, with possible repercussions beyond intrauterine life. The objective of this study was to establish reference curves for fetal kidney dimensions and volume from 14 to 40 weeks of gestation.

METHODS

This is a prospective longitudinal study of 115 Brazilian participants in the "WHO multicentre study for the development of growth standards from fetal life to childhood: the fetal component". Pregnant women with clinical and sociodemographic characteristics allowing the full potential fetal growth were followed up from the first trimester until delivery. These women underwent serial sonographic evaluation of fetal kidneys. The longitudinal, anteroposterior and transverse diameters of both fetal kidneys were measured, in addition to calculation of kidney volume. By quantile regression analysis, reference curves of renal measurements related to gestational age were built.

RESULTS

Standard normal sonographic values of renal biometry were defined during pregnancy. Reference values for the 10th, 50th and 90th centiles of different fetal kidney measurements (longitudinal, anteroposterior, transverse and volume) from the 14th to the 40th week of gestation were fitted.

CONCLUSION

The reference curves presented should be of the utmost importance for screening and diagnosis of alterations in renal development during the intrauterine period.

Fetal Adrenal Gland Volume a Novel Predictor of Onset of Labor

Introduction

There is a definite need to find a highly sensitive and specific, noninvasive, and cost-effective marker for prediction of preterm labor. We hypothesize that a measurement of adrenal gland volume can predict a preterm as well as a term labor.

Materials and Methods

Two hundred and sixty-eight pregnant women were enrolled in the study at 28-34 weeks' antenatal visit. Final analysis was done in 204. All of them were subjected to 2D ultrasonographic measurement of the corrected fetal adrenal gland volume (cFAGV) and fetal adrenal zone parameters including the width ratio and depth ratio. The cohort was followed up to term, and a reassessment of cFAGV and fetal adrenal zone parameters was repeated between 37 and 39 weeks. Women who presented with features of preterm labor had a scan at the time of presentation to record cFAGV and fetal adrenal zone parameters.

Results

Women, who developed features of preterm labor eventually, had a significantly high cFAGV (404.70 mm³/kg body weight) during the first scan compared to those who reached term asymptomatically (241.35 mm³/kg body weight). A cutoff value of 271.16 mm³/kg body weight showed 90% sensitivity and 81.9% specificity. Fetal adrenal gland width ratio had the best efficacy (sensitivity 96.67%, specificity 86.2%) followed by cFAGV (sensitivity 96.67%, specificity 83%) for predicting preterm delivery.

Conclusion

2D ultrasound measurement of fetal adrenal gland parameters can be used as a marker for prediction of preterm delivery. cFAGV at term can also be used to predict the possibility of spontaneous onset of labor.

Adrenal gland size in growth restricted fetuses

Objective To compare the adrenal gland size of fetal growth restricted (FGR) and normal control fetuses. Study design In this prospective study the adrenal gland size of 63 FGR fetuses and 343 normal controls was measured between 20 and 41 weeks of gestation. The total width and the medulla width were measured in a new standardized transversal plane. The cortex width and a calculated ratio of the total and medulla width (adrenal gland ratio) were compared between both groups. Results The mean cortex width and the adrenal gland ratio in FGR fetuses were higher in comparison to the controls (P<0.001; P=0.036, respectively). The cortex width correlated positively with the gestational age (control group: P<0.001; FGR group: P=0.089) whilst the adrenal gland ratio showed no association with the gestational age (control group: P=0.153; FGR group: P=0.314). Conclusion The adrenal gland cortex width and the adrenal gland ratio were increased in FGR fetuses compared to normal fetuses.

Imaging of Nonmalignant Adrenal Lesions in Children

The adrenal glands in children can be affected by a variety of benign lesions. The diagnosis of adrenal lesions can be challenging, but assessment of morphologic changes in correlation with the clinical presentation can lead to an accurate diagnosis. These lesions can be classified by their cause: congenital (eg, discoid adrenal gland, horseshoe adrenal gland, and epithelial cysts), vascular and/or traumatic (eg, adrenal hemorrhage), infectious (eg, granulomatous diseases), enzyme deficiency disorders (eg, congenital adrenal hyperplasia [CAH] and Wolman disease), benign neoplasms (eg, pheochromocytomas, ganglioneuromas, adrenal adenomas, and myelolipomas), and adrenal mass mimics (eg, extralobar sequestration and extramedullary hematopoiesis). Multimodality cross-sectional imaging helps to define the origin, extent, and relationship of these lesions to adjacent structures, as well as to guide treatment management. The anatomic and functional imaging modalities used to evaluate pediatric adrenal lesions include ultrasonography, computed tomography (CT), magnetic resonance imaging, and iodine 123 metaiodobenzylguanidine scintigraphy. Identifying the imaging features of nonmalignant adrenal lesions is helpful to distinguish these lesions from malignant adrenal neoplasms. Identifying characteristic imaging findings (eg, enlarged adrenal glands, with cerebriform surface, and stippled echogenicity in CAH; a T2-hyperintense mass with avid contrast enhancement in pheochromocytoma; low CT attenuation [<10 HU] and signal intensity drop on opposed-phase chemical shift images in adenoma; and enhancing suprarenal mass supplied by a systemic feeding artery in extralobar sequestration) can aid in making the correct diagnosis. In addition, clinical features (eg, ambiguous genitalia in CAH and hypertension in pheochromocytoma) can also guide the radiologist toward the correct diagnosis. ^©RSNA, 2017.

Ultrasound measurement of fetal adrenal gland in fetuses with intrauterine growth restriction, an early predictive method for adverse outcomes

OBJECTIVES

Comparing the sonographic measurements of fetal adrenal gland in pregnancies with intrauterine growth restriction (IUGR) versus healthy controls and to assess whether the changes in adrenal gland measurements could predict adverse pregnancy outcomes in IUGR fetuses.

METHODS

This prospective cohort study evaluated 97 pregnant women (48 with IUGR pregnancies and 49 healthy controls) during their third gestational trimester. All mothers underwent two dimensional ultrasonography of the fetal adrenal gland, and the fetal zone in transverse, sagittal, and coronal planes. Adrenal gland volume (AGV) and fetal zone volume (FZV) were calculated and corrected (c) for fetal weight. The mothers were then followed until delivery.

RESULTS

Fetuses in the IUGR group had larger corrected adrenal gland volume (c_AGV) and smaller corrected fetal zone volume (c_FZV) compared to the fetuses in the control groups (p < .001). In the IUGR group, significantly smaller c_AGV and higher fetal/adrenal were detected in IUGR fetuses who had nonreassuring fetal status before delivery, preterm birth, very low birth weight delivery, and also those who required neonatal intensive care unit admission (p < .01 for all).

CONCLUSIONS

Third trimester fetal adrenal gland sonography could potentially be used as an easy noninvasive method for identifying those IUGR fetuses who might have poorer outcomes.

Evaluation of fetal kidney growth using ultrasound: A systematic review

PURPOSE

To determine the role of ultrasound imaging in evaluating fetal kidney growth.

METHODS

MEDLINE, CINAHL and EMBASE databases were electronically searched for studies between 1996 and January 2017 and limited to English language. Studies were included if they reported on an ultrasound technique to assess fetal kidney growth and they were not a case report or case series. There was independent selection of studies by two reviewers in consensus with one other reviewer. Data were extracted by one reviewer in consensus with two other reviewers.

RESULTS

A total of 1785 articles were identified. The full text of 39 of these were assessed for eligibility for inclusion. Twenty-eight studies were then included in the review. Standard two dimensional (2D) fetal renal measurements are easy to perform, however, this review identified that most studies had some methodological limitations. The disadvantage with 2D and three dimensional (3D) fetal renal volumes are that they include the entire kidney and good reproducibility of 3D volumes has not yet been demonstrated. Currently there is limited research on fetal kidney growth in the setting of abnormal fetal growth. Research focussing directly on fetal kidney parenchyma and blood flow is scarce.

CONCLUSIONS

Some nomograms of 2D and 3D fetal kidney size and volume have been developed. Kidney length is the most popular single fetal kidney measurement; however, it does not seem to be a good indicator of growth. In IUGR fetuses, kidney length remained similar to appropriately grown fetuses whereas AP and TS dimensions were significantly decreased. New ultrasound techniques focusing on the parenchyma of the kidney and perfusion to the kidney should be explored as they may provide more meaningful information on kidney development in the fetus and future kidney function.

Prenatal compensatory renal growth in unilateral renal agenesis

OBJECTIVE

To create nomograms of fetal renal compensatory growth in cases of unilateral renal agenesis (URA).

METHODS

A retrospective study of fetuses with isolated URA diagnosed prenatally, and confirmed postnatal was performed.

RESULTS

Seventy-four fetuses with isolated solitary kidney were included in the study. A total of 134 measurements of the kidney's length were performed. Ninety five of them were studied longitudinally (2-6 measurements each). The raw values of the compensatory kidney demonstrated a significant correlation with gestational age (Pearson correlation coefficient 0.901, p < 0.001). A quadratic/cubic regression curve, both, described best this relationship, -26.400 + 3.004*GA, -0.026*GA² (r²  = 0.819). The Z score between the mean predicted compensatory kidney's length, per week of gestation, and the mean predicted values of normal kidney length as previously published in the literature, progressively increased during pregnancy (cubic r²  = 0.946 and 0.260).

CONCLUSION

Cases of URA show a unique growth pattern of the single kidney from second trimester to term. Postnatal renal function is dependent on adequate intra-uterine compensatory growth; the presented nomograms provide insight into renal prognosis and add paramount information to the multidisciplinary prenatal counseling of the future parents. © 2016 John Wiley & Sons, Ltd.

Classification of pediatric urinary tract dilation: the new language

The multidisciplinary consensus on the classification of prenatal and postnatal urinary tract dilation (UTD classification system) was created to unify the language used to describe urinary tract dilation on antenatal and postnatal ultrasound examinations and thereby facilitate communication among providers and improve outcomes research. The background and new classification system are described in this review, with imaging examples.

A possible new approach in the prediction of late gestational hypertension: The role of the fetal aortic intima-media thickness

The aim was to determine the predictive role of combined screening for late-onset gestational hypertension by fetal ultrasound measurements, third trimester uterine arteries (UtAs) Doppler imaging, and maternal history. This prospective study on singleton pregnancies was conducted at the tertiary center of Maternal and Fetal Medicine of the University of Padua during the period between January 2012 and December 2014. Ultrasound examination (fetal biometry, fetal wellbeing, maternal Doppler study, fetal abdominal aorta intima-media thickness [aIMT], and fetal kidney volumes), clinical data (mother age, prepregnancy body mass index [BMI], and parity), and pregnancy outcomes were collected. The P value <0.05 was defined significant considering a 2-sided alternative hypothesis. The distribution normality of variables were assessed using Kolmogorov-Smirnoff test. Data were presented by mean (±standard deviation), median and interquartile range, or percentage and absolute values. We considered data from 1381 ultrasound examinations at 29 to 32 weeks' gestation, and in 73 cases late gestational hypertension developed after 34 weeks' gestation. The final multivariate model found that fetal aIMT as well as fetal umbilical artery pulsatility index (PI), maternal age, maternal prepregnacy BMI, parity, and mean PI of maternal UtAs, assessed at ultrasound examination of 29 to 32 weeks' gestation, were significant and independent predictors for the development of gestational hypertension after 34 weeks' gestation. The area under the curve of the model was 81.07% (95% confidence interval, 75.83%-86.32%). A nomogram was developed starting from multivariate logistic regression coefficients. Late-gestational hypertension could be independently predicted by fetal aIMT assessment at 29 to 32 weeks' gestation, ultrasound Doppler waveforms, and maternal clinical parameters.

The World's Youngest Cadaveric Kidney Transplant: Medical, Surgical and Ethical Issues

Background

We report here the first successful transplant from a preterm cadaveric donor. This was performed in November 1994. The donor, who had been born at about 33 weeks of gestation, was diagnosed as having agenesis of the corpus callosum. The transplant was carried out 10 days after the donor's birth. The recipient was a 17-month-old boy with a diagnosis of Denys-Drash syndrome (WT1 mutation).

Method

We describe and analyze the ethical, social, cultural, medical and surgical issues encountered and how these were addressed. The major issue of determining death in a beating heart, very young donor was dealt with in the absence of worldwide experience and guidelines.

Results

The transplanted recipient has lived with the grafted pair of kidneys for more then 22 years. He has led a relatively normal life.

Conclusions

It is possible for immature preterm deceased donor kidneys to be transplanted into a 17-month-old recipient and for the grafted kidneys to grow with the recipient and function for 22 years. There were challenges in ethically determining the death of the donor, in surgical techniques to obviate potential surgical complications, and in postoperative care of the recipient, but these were managed successfully.

MRI-based reference range for the renal pelvis anterior-posterior diameter in children ages 0-19 years

OBJECTIVE

To determine the mean and normal range of anteroposterior diameter (APD) of the renal pelves in children.

METHODS

Patients aged 0-19 years with normal spinal MRIs were identified after institutional review board approval. Those with dilating uropathy or abdominal surgery/radiation were excluded. The maximum APD was measured. A mixed linear model was fit to determine the relationship between APD and age, adjusted for bladder distention. The left and right kidneys were treated independently.

RESULTS

283 left and 285 right renal units were included. For the left, a 3.5% increase in APD per year was predicted (p < 0.0001), with the average APD for infants and 18-year olds with non-distended bladders being 2.5 mm (95th percentile: 7.2 mm) and 4.6 mm (13.4 mm), respectively. For the right, a 3.9% increase in APD per year was predicted (p < 0.0001), with the average APD for infants and 18-year olds with non-distended bladders being 2.8 mm (8.4 mm) and 5.5 mm (16.6 mm), respectively. Compared with a non-distended bladder, a distended bladder increased the predicted APD between 23% (right) and 38% (left) (p = 0.01 and p < 0.0001, respectively).

CONCLUSION

The mean and normal ranges of APD measured by MRI in children are provided. APD increases with age and bladder distension and is greater on the left. Advances in knowledge: This article establishes normative ranges for APD, a critical component of genitourinary tract evaluation, and does so using the most precise imaging modality for this condition.

Fetal growth profiles of macrosomic and non-macrosomic infants of women with pregestational or gestational diabetes

OBJECTIVE

To assess fetal growth profiles in an unselected group of pregnant women with either type-1 diabetes (DM1), type-2 diabetes (DM2) or gestational diabetes (GDM), with emphasis on intergroup differences and development of disproportionate fetal growth and macrosomia.

METHODS

Second- and third-trimester longitudinal ultrasound measurements of fetal growth were made in 77 women with DM1, 68 women with DM2 and in 99 women with GDM. Altogether 897 ultrasound examinations were performed and 145 uncomplicated pregnancies with 843 ultrasound examinations were included as controls. Ultrasound data included head circumference (HC), abdominal circumference (AC), femur length (FL) and HC/AC ratio.

RESULTS

The AC, but not HC and FL, evolved differently in diabetic pregnancies, with a smaller AC in early pregnancy and larger AC at term (significant for DM1 and DM2). The most striking differences were found for the HC/AC ratio, especially in DM1 pregnancies. HC/AC growth trajectories of both macrosomic and non-macrosomic fetuses differed from that of the controls, and the HC/AC ratio at term was lower in all diabetic subgroups except in non-macrosomic DM2 cases.

CONCLUSION

We found altered (disproportionate) fetal growth in macrosomic and non-macrosomic fetuses of women with DM1, DM2 and GDM. This indicates that the abnormal intrauterine environment affects the majority of these infants. Growth profiles differed among these groups, the most prominent growth deviations being found in the fetuses of women with DM1. The latter was most probably caused by poor glucose control. In monitoring fetal growth in diabetic pregnancies the HC/AC ratio should be used to assess altered fetal growth.

Compensatory enlargement of a solitary functioning kidney during fetal development

OBJECTIVE

To determine the degree of compensatory enlargement, and its time of onset, of the solitary functioning kidney (SFK) in fetuses with unilateral renal agenesis (URA) or unilateral multicystic kidney dysplasia (MCKD).

METHODS

This was a retrospective study of fetuses with URA or MCKD diagnosed prenatally and confirmed postnatally in the period from January 1999 to May 2011. Fetuses with any other congenital anomalies were excluded. Measurements of kidney length were retrieved from our prenatal ultrasound database and a nomogram was established and compared with that for normal kidney length.

RESULTS

In total, 67 fetuses were identified, 60 with MCKD and seven with URA, for which we obtained 147 kidney length measurements from our database. Mean gestational age at time of measurement was 29.7 (range, 18.4-36.7) weeks. Compensatory enlargement, defined as renal length >95(th) percentile for gestational age, was demonstrated in 87% of the MCKD cases and 100% of the URA cases (88% of cases overall). We estimated the mean enlargement for an SFK (defined as difference from 50(th) percentile for normal renal length) at 36 weeks' gestation to be 23.1% (9.25 mm), with the mean value being 11.4% (5.04 mm) greater than the 95(th) percentile for a normal kidney at this gestational age. Compensatory enlargement of SFKs was evident from the 20(th) week of gestation onwards.

CONCLUSION

Compensatory enlargement of SFKs occurs in almost 90% of fetuses with MCKD or URA, and may be observed from the 20(th) week of gestation onwards.

Compensatory growth of congenital solitary kidneys in pigs reflects increased nephron numbers rather than hypertrophy

Background

Patients with unilateral MultiCystic Kidney Dysplasia (MCKD) or unilateral renal agenesis (URA) have a congenital solitary functioning kidney (CSFK) that is compensatory enlarged. The question whether this enlargement is due to increased nephron numbers and/or to nephron hypertrophy is unresolved. This question is of utmost clinical importance, since hypertrophy is associated with a risk of developing hypertension and proteinuria later in life with consequent development of CKD and cardiovascular disease.

Methodology/Principal Findings

In a cohort of 32,000 slaughter pigs, 7 congenital solitary functioning kidneys and 7 control kidneys were identified and harvested. Cortex volume was measured and with a 3-dimensional stereologic technique the number and volume of glomeruli was determined and compared. The mean total cortex volume was increased by more than 80% and the mean number of glomeruli per kidney was 50% higher in CSFKs than in a single control kidney, equaling 75% of the total nephron number in both kidneys of control subjects. The mean total glomerular volume in the CSFKs was not increased relative to the controls.

Conclusions/Significance

Thus, in pigs, compensatory enlargement of a CSFK is based on increased nephron numbers. Extrapolation of these findings to the human situation suggests that patients with a CSFK might not be at increased risk for developing hyperfiltration-associated renal and cardiovascular disease in later life due to a lower nephron number.