Management of patients with posterior urethral valves "from the fetus to adolescence": French national diagnostic and care protocol (NDCP)

Posterior urethral valves (PUV) are congenital anomalies characterized by the persistence of mucosal folds in the urethra, leading to various degrees of obstruction. They are the most common cause of lower urinary tract obstruction in fetuses and children, with a severe prognosis, as one-third of affected children develop end-stage renal disease before adulthood. The French National Diagnostic and Care Protocol (NDCP) aim to provide healthcare professionals with guidelines for the optimal diagnostic and therapeutic management of PUV from the fetal stage to adolescence. The guidelines emphasize early diagnosis through prenatal ultrasound and the importance of a multidisciplinary approach involving pediatric urologists, nephrologists, and other specialists. It outlines prenatal interventions such as vesico-amniotic shunting and postnatal surgical options like endoscopic valve ablation to alleviate obstruction and preserve renal function. Long-term follow-up is crucial for monitoring renal function, managing bladder dysfunction, and preventing complications such as urinary tract infections and chronic kidney disease. The guidelines also identify off-label pharmaceuticals and necessary specialty products not typically covered by insurance. By standardizing care pathways and promoting consistent, high-quality care, the guidelines aim to improve the prognosis and quality of life for children with PUV, setting a benchmark for managing this rare condition in pediatric urology.

Urine Biochemistry of a Human Fetus with Urinary Tract Obstruction - A Case Report

INTRODUCTION

Fetal lower urinary tract obstruction (LUTO) can be mild or severe with oligohydramnios, renal dysplasia and pulmonary hypoplasia. Fetal urine biochemical markers correlate with fetal prognosis and, if favorable, surgical intervention is feasible.

METHODS

We report a patient in her 18th gestational week whose fetus was diagnosed with LUTO and underwent fetal urine sampling for calcium, sodium, chloride, beta2-microglobulin and total protein of the routine LUTO panel, with the addition of creatinine, glucose, phosphate, urea, ammonia, albumin, and NGAL.

RESULTS

Although the routine fetal urine biochemistry seemed to be favorably trending favorably, sodium, beta2-microglobulin, glucose, and urea did not decrease to the reference ranges, and ammonia and creatinine were lower than the reference ranges. Ultrasound demonstrated no improvement of the obstruction.

CONCLUSIONS

This case highlights the need to acquire further experience with biochemical fetal urine markers in order to better manage LUTO.

Quantification of Fetal Renal Function Using Fetal Urine Production Rate and Its Reflection on the Amniotic and Fetal Creatinine Levels During Pregnancy

Adequate prediction of fetal exposure of drugs excreted by the kidney requires the incorporation of time-varying renal function parameters into a pharmacokinetic model. Published data on measurements of fetal urinary production rate (FUPR) and creatinine at various gestational ages were collected and integrated for prediction of the fetal glomerular filtration rate (GFR). The predicted GFR values were then compared to neonatal values recorded at birth. Collected data for FUPR across different gestational ages using both 3D (N = 517) and 2D (N = 845) ultrasound methods showed that 2D techniques yield significantly lower estimates of FUPR than 3D (p < 0.0001). A power law function was shown to best capture the change in FUPR with fetal age (FA) for both 2D ( F U P R 2 D ( m L min ) = 0 . 000169     FA 2 . 19 ); and 3D ( F U P R 3 D   ( m L min ) =   3 . 21 × 1 0 - 7   FA 4 . 21 ) data. The predicted FUPR based on the observed 3D data was shown to be strongly linearly related (R ² = 0.95) to measured values of amniotic creatinine concentration (N = 664). The FUPR_3D data together with creatinine levels in the fetal urine and serum resulted in median predicted fetal GFR values of 0.47, 1.2, 2.5, and 4.9 ml/min at 23, 28, 33, and 38 weeks of fetal age (50% CV), respectively. These values are in good agreement with neonatal values observed immediately at birth. The derived FUPR and creatinine functions can be utilized to assess fetal renal maturation and predict fetal renal clearance.

Brain structure and perfusion in relation to serum renal function indexes in healthy young adults

Prior neuroimaging studies of the relationship between the kidney and the brain have been limited to clinical populations and have largely relied on a single modality. We sought to examine the kidney-brain associations in healthy subjects using a combined analysis of multi-modal imaging data. Structural, diffusion, and perfusion magnetic resonance imaging (MRI) scans were performed to measure cortical thickness, white matter integrity, and cerebral blood flow in 157 healthy young adults. Peripheral venous blood samples were collected to measure serum renal function indexes. Correlation analyses were performed to investigate the relations between brain MRI measures and renal function indexes. Results showed that higher serum uric acid level was associated with increased cortical thickness in the transverse temporal gyrus. We also found that decreased serum creatinine level was linked to lower white matter integrity in the sagittal stratum, anterior corona radiata, superior corona radiata, and external capsule. Furthermore, we observed that increased serum uric acid level was related to hyperperfusion in the opercular and triangular parts of inferior frontal gyrus and supramarginal gyrus, and hypoperfusion in the calcarine sulcus, cuneus and lingual gyrus. More importantly, mediation analysis revealed that the relationship between serum uric acid and working memory performance was mediated by perfusion in the supramarginal gyrus and lingual gyrus. These findings not only may extend current knowledge regarding the relationship between the kidney and the brain, but also may inform real-world clinical practice by identification of potential brain regions vulnerable to renal dysfunction.

Prenatal diagnosis of megacystis-microcolon-intestinal hypoperistalsis syndrome

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) is a rare congenital disorder, acknowledged as the most debilitating form of chronic intestinal pseudoobstruction disorders. Because the disease is often fatal in the first years of life and the surviving individuals are dependent on supportive medical or surgical treatment, definite antenatal diagnosis is desirable. We report a case of prenatally diagnosed MMIHS and discuss the suspicious findings and diagnostic criteria that allow a rapid and definite prenatal diagnosis.

Prediction model of postnatal renal function in fetuses with lower urinary tract obstruction (LUTO)-Development and internal validation

OBJECTIVE

To develop a prediction model of postnatal renal function in fetuses with lower urinary tract obstruction (LUTO) based on fetal ultrasound parameters and amniotic fluid volume.

METHODS

Retrospective nationwide cohort study of fetuses with postnatally confirmed LUTO and known eGFR. Fetuses treated with fetal interventions such as vesico-amniotic shunting or cystoscopy were excluded. Logistic regression analysis was used to identify prognostic ultrasound variables with respect to renal outcome following multiple imputation of missing data. On the basis of these fetal renal parameters and amniotic fluid volume, a model was developed to predict postnatal renal function in fetuses with LUTO. The main study outcome was an eGFR less than 60 mL/min * 1.73 m² based on the creatinine nadir during the first year following diagnosis. Model performance was evaluated by receiver operator characteristic (ROC) curve analysis, calibration plots, and bootstrapping.

RESULTS

Hundred one fetuses with a confirmed diagnosis of LUTO were included, eGFR less than 60 was observed in 40 (39.6%) of them. Variables predicting an eGFR less than 60 mL/min * 1.73m² included the following sonographic parameters: hyperechogenicity of the renal cortex and abnormal amniotic fluid volume. The model showed fair discrimination, with an area under the ROC curve of 0.70 (95% confidence interval, 0.59-0.81, 0.66 after bootstrapping) and was overall well-calibrated.

CONCLUSION

This study shows that a prediction model incorporating ultrasound parameters such as cortical appearance and abnormal amniotic fluid volume can fairly discriminate an eGFR above or below 60 mL/min * 1.73m² . This clinical information can be used in identifying fetuses eligible for prenatal interventions and improve counseling of parents.

Urine biochemistry to predict long-term outcomes in fetuses with posterior urethral valves

OBJECTIVE

Because the literature on the predictive value of fetal urinalysis is controversial in fetuses with lower urinary tract obstruction, we determined the best model of fetal urine biochemical markers correlated with long-term postnatal renal function based on glomerular filtration rate (GFR).

METHOD

This retrospective study concerned 89 fetuses with lower urinary tract obstruction and their renal function after 10 years of age. We correlated fetal urine biochemical markers (total protein, β2-microglobulin, sodium, chloride, glucose, calcium, and phosphorus) with GFR at 10 to 30 years of age in 89 patients with posterior urethral valves. We defined five stages of chronic kidney disease (CKD).

RESULTS

Of the 89 patients, 18 (20%) are 20 years old or over. Postnatal renal function was good in 67.4% (GFR > 60 mL/min/1.73 m² ) and poor in 17% (GFR < 30 mL/min/1.73 m² ). All fetal urine markers differed between CKD stage 1 + 2 and CKD stage 4 + 5 (P < 0.001). β2-microblobulin showed an 87% sensitivity for a 72% specificity. A combination of β2-microglobulin and chloride gave the best results (93% sensitivity and 71% specificity) versus amniotic fluid volume (80% sensitivity and 73% specificity).

CONCLUSION

Fetal urine biochemistry predicts long-term (10-30 years) postnatal renal function.

Physiological, hematological and biochemical factors associated with high-altitude headache in young Chinese males following acute exposure at 3700 m

BACKGROUND

High-altitude headache (HAH) is the most common sickness occurred in healthy people after rapid ascending to high altitude, and its risk factors were still not well understood. To investigate physiological, hematological and biochemical risk factors associated with high-altitude headache (HAH) after acute exposure to 3700 m, we conducted a two-stage, perspective observational study. In 72 h, total 318 young Han Chinese males ascended from sea level (altitude of 50 m) to altitude of 3700 m by train. Demographic data, physiological, hematological and biochemical parameters of all participants were collected within one week prior to the departure, and within 24 h after arrival.

RESULTS

The incidence of HAH was 74.84%. For parameters measured at sea level, participants with HAH exhibited significantly higher age and lower BUN (p < 0.05). For parameters measured at 3700 m, participants with HAH exhibited significantly lower blood oxygen saturation (SpO2), higher resting heart rate (HR), higher systolic blood pressure at resting (SBP) and lower blood urea nitrogen (BUN) (all p < 0.05). At 3700 m, the severity of HAH associated with SpO2, HR and BUN significantly (all p < 0.05). Multivariate logistic regression revealed that for parameters at sea level, BUN was associated with HAH [BUN (OR:0.77, 95% CI:0.60-0.99)] and for parameters at 3700 m, SpO2, HR and BUN were associated with HAH independently [SpO2 (OR:0.84, 95% CI:0.76-0.93); HR (OR:1.03, 95% CI:1.00-1.07); BUN (OR:0.64, 95% CI:0.46-0.88)]. No association between hematological parameters and HAH was observed.

CONCLUSION

We confirmed that higher HR, lower SpO2 are independent risk factors for HAH. Furthermore, we found that at both 50 m and 3700 m, lower BUN is a novel independent risk factor for HAH, providing new insights for understanding the pathological mechanisms.

Comparison of biochemical analysis of fetal serum and fetal urine in the prediction of postnatal renal outcome in lower urinary tract obstruction

OBJECTIVES

To compare the prognostic value of fetal serum biochemistry and fetal urine biochemistry in predicting renal outcome in lower urinary tract obstruction (LUTO).

METHODS

We retrospectively studied renal outcome following a prenatal diagnosis of LUTO in cases for which both fetal blood and fetal urine were sampled. We classified the renal outcome as either "favorable," when postnatal renal function was normal, or "adverse," in the case of postnatal chronic renal failure or when renal histological lesions were present at autopsy in the case of termination of pregnancy. A prognostic model was constructed for urine and serum separately. β2-Microglobulin was the only remaining independent predictor in fetal urine. β2-Microglobulin in serum and urine were compared by using receiver operating characteristic curves.

RESULTS

In the 50 cases included, the rate of adverse outcome was 34 of 50(68%): autopsy confirmed severity of renal disease in all 27 cases who underwent termination of pregnancy, and among the 23 live born children, 7 developed renal failure. Fetal serum and urine markers were all significantly associated with renal outcome (P < .01). The receiver operating characteristic curves for fetal serum and fetal urinary β2-microglobulin were similar (area under the curve = 0.908 versus 0.909, P = .96).

CONCLUSION

Fetal serum biochemistry and fetal urine biochemistry are of similar prognostic value in predicting postnatal renal outcome in fetuses with LUTO.

Lower urinary tract obstruction: fetal intervention based on prenatal staging

The authors present an overview of lower urinary tract obstruction (LUTO) in the fetus with a particular focus on the insult to the developing renal system. Diagnostic criteria along with the challenges in estimating long-term prognosis are reviewed. A proposed prenatal LUTO disease severity classification to guide management decisions with fetal intervention to maintain or salvage in utero and neonatal pulmonary and renal function is also discussed. Stage I LUTO (mild form) is characterized by normal amniotic fluid index after 18 weeks, normal kidney echogenicity, no renal cortical cysts, no evidence of renal dysplasia, and favorable urinary biochemistries when sampled between 18 and 30 weeks; prenatal surveillance is recommended. Stage II LUTO is characterized by oligohydramnios/anhydramnios, hyperechogenic kidneys but absent renal cortical cysts or apparent signs of renal dysplasia and favorable fetal urinary biochemistry; fetal vesicoamniotic shunting (VAS) or fetal cystoscopy is indicated to prevent pulmonary hypoplasia and renal failure. Stage III LUTO is oligohydramnios/anhydramnios, hyperechogenic kidneys with cortical cysts and renal dysplasia and unfavorable fetal urinary biochemistry after serial evaluation; fetal vesicoamniotic shunt may prevent severe pulmonary hypoplasia but not renal failure. Stage IV is characterized by intrauterine fetal renal failure, defined by anhydramnios and ultrasound (US) findings suggestive of severe renal dysplasia, and is associated with death in 24 h of life or end-stage renal disease (ESRD) within the first week of life; fetal vesicoamniotic shunt and fetal cystoscopy are not indicated.

Renal adaptive changes and sodium handling in the fetal-to-newborn transition

Appropriate fluid and electrolyte management is critical for optimal care of very low birth weight or sick infants. Delivery of such care requires an understanding of developmental changes in renal water and salt handling that occur with advancing gestational age as well as postnatal age. This review focuses on the principles of sodium homeostasis during fetal and postnatal life. The physiology of renal tubular transport mechanisms, as well as neurohumoral factors impacting renal tubular transport are highlighted. Clinical implications and guidelines to the provision of sodium to this vulnerable population are also discussed.

Posterior urethral valves: Impact of low birth weight and preterm delivery on the final renal outcome

Objective

To investigate the relationship between low birth weight (LBW; <2.5 kg) and preterm delivery (<37 weeks gestational age) and final renal outcome in infants with posterior urethral valves (PUVs), emphasising the risk factors for the development of chronic kidney disease (CKD).

Patients and methods

A retrospective review was performed for all infants with PUVs who were treated between 1990 and 2010. In all, 52 infants were identified to have LBW and/or delivered preterm (Group 1). Infants in Group 1 were compared with a matching group (Group 2) of 60 full-term normal birth weight (NBW) infants with PUVs managed during the same period. The outcome of both groups was analysed.

Results

During follow-up, CKD developed in 17 (32.5%) and 22 patients (36.5%) in Groups 1 and 2, respectively (P = 0.812). Patients with LBW or delivered preterm had significantly higher incidence of oligohydramnios (P = 0.009), increased risk of vesicostomy (P < 0.001), longer hospital stay (P < 0.001), and higher incidence of vesico-ureteric reflux (VUR, P = 0.024). In the LBW patients, initial serum creatinine, nadir serum creatinine, oligohydramnios and Neonatal Intensive Care Unit (NICU) length of stay were significant predictors of final renal outcome (P < 0.001, P = 0.002, P = 0.004 and P = 0.012, respectively).

Conclusion

In our cohort of LBW and preterm delivery infants with PUVs, outcomes were similar to those of NBW full-term infants with PUVs but with an increased risk of vesicostomy, longer hospital stay, and higher incidence of VUR. LBW was associated with oligohydramnios, longer NICU admission, high initial and nadir serum creatinine, which were associated with a poor prognosis.

Fetal urine biochemistry in antenatal Bartter syndrome: a case report

Bartter syndrome is a severe inherited tubulopathy responsible for renal salt wasting, and hence electrolyte disorders and dehydration. Prenatally, it is characterized by severe polyhydramnios caused by fetal polyuria. We studied for the first time fetal urine in a Bartter syndrome case and demonstrated that the tubulopathy is already present at 24 weeks of gestation.

Current applications of in utero intervention for lower urinary tract obstruction

PURPOSE

Since the early 1980s with the inception of fetal intervention for obstructive uropathy, there have been creative attempts to improve both perinatal and long-term outcomes. Despite advances in technology and an improved understanding of lower urinary tract obstruction (LUTO) in the fetus, the results for these therapeutic interventions remain guarded and the long-term renal morbidity among survivors remains problematic.

RECENT FINDINGS

Fetal LUTO represents a range of disorders but the most common of these is posterior urethral valves (PUVs). Selection criteria for candidates of possible intervention have improved with our understanding of fetal renal physiology. Serial urinalysis has marginally improved our ability to predict those that may ultimately respond to treatment [1,2], but the potential in the development of biomarkers for renal development or maldevelopment holds greater promise [3]. Advancements in fetal surgery may result in less fetal and maternal morbidity, but limited long-term improvement in outcomes highlights the controversial nature of the various interventions [4-10]. We must counsel families that fetal surgery offers hope but we cannot allow them to hold unrealistic expectations for cure.

SUMMARY

In appropriately selected fetuses, intervention may improve perinatal survival but not without risk to mother and fetus. Long-term renal outcomes remain problematic amongst survivors. In the case of PUV, postnatal primary valve ablation remains the cornerstone of treatment for nephron preservation; however, our ability to mimic these results in the prenatal population remains poor [11]. Disease severity has likely predetermined those that will survive through the perinatal period with or without intervention. Nonetheless, our drive to assess and manage fetal obstructive uropathy perseveres so that we may ultimately relieve obstruction and preserve renal and lung function. We must maintain optimism that continued advances will ultimately improve outcomes, but also be realistic with our current expectations. This paper reviews the status of current in utero interventions and outcomes.

Fetal urine biochemistry at 13-23 weeks of gestation in lower urinary tract obstruction: criteria for in-utero treatment

OBJECTIVES

To assess the value of fetal urine biochemistry before 23 weeks of gestation in cases of lower urinary tract obstruction (LUTO) to refine prognosis and to select potential candidates for in-utero intervention.

METHODS

This was a retrospective study including 72 cases of LUTO with fetal urine sampled before 23 weeks and assayed for total protein, β-2-microglobulin, sodium, chloride, calcium, phosphorus, glucose and gamma-glutamyl transpeptidase (GGTP). Two groups were defined according to renal outcome: 1) bilateral renal dysplasia on histological examination or renal failure at birth; 2) normal postnatal renal function or histologically normal appearance of the kidneys. Correlations between fetal urinary biochemical markers and postnatal renal function were studied.

RESULTS

LUTO was isolated in 56/72 (77.8%) cases and was associated with other malformations in 16/72 (22.2%) cases. High GGTP levels (236 IU/L vs 5 IU/L; P < 0.0001) were observed in fetal urine in the five cases of urodigestive fistula. A significant difference between outcome groups was observed for β-2-microglobulin (P = 0.0017), sodium (P = 0.0008), chloride (P = 0.0028) and calcium (P = 0.0092) but not for protein, glucose or phosphorus. Sensitivity and specificity in defining a poor renal prognosis were 80.6% and 89% for β-2-microglobulin, 61.3% and 100% for sodium and 64.5% and 100% for calcium, respectively.

CONCLUSIONS

Fetal urinalysis before 23 weeks of gestation allowed distinction between three groups: 1) fetuses with normal urine biochemistry for which fetal therapy should be discussed; 2) fetuses with abnormal urine biochemistry for which prognosis for renal outcome is poor and for which the benefit of fetal therapy is likely to be compromised; 3) fetuses with urodigestive fistula.

Arterial flow regulator enables transplantation and growth of human fetal kidneys in rats

Here we introduce a novel method of transplanting human fetal kidneys into adult rats. To overcome the technical challenges of fetal-to-adult organ transplantation, we devised an arterial flow regulator (AFR), consisting of a volume adjustable saline-filled cuff, which enables low-pressure human fetal kidneys to be transplanted into high-pressure adult rat hosts. By incrementally withdrawing saline from the AFR over time, blood flow entering the human fetal kidney was gradually increased until full blood flow was restored 30 days after transplantation. Human fetal kidneys were shown to dramatically increase in size and function. Moreover, rats which had all native renal mass removed 30 days after successful transplantation of the human fetal kidney were shown to have a mean survival time of 122 days compared to 3 days for control rats that underwent bilateral nephrectomy without a prior human fetal kidney transplant. These in vivo human fetal kidney models may serve as powerful platforms for drug testing and discovery.

Prevention of the disrupted enamel phenotype in Slc4a4-null mice using explant organ culture maintained in a living host kidney capsule

Slc4a4-null mice are a model of proximal renal tubular acidosis (pRTA). Slc4a4 encodes the electrogenic sodium base transporter NBCe1 that is involved in transcellular base transport and pH regulation during amelogenesis. Patients with mutations in the SLC4A4 gene and Slc4a4-null mice present with dysplastic enamel, amongst other pathologies. Loss of NBCe1 function leads to local abnormalities in enamel matrix pH regulation. Loss of NBCe1 function also results in systemic acidemic blood pH. Whether local changes in enamel pH and/or a decrease in systemic pH are the cause of the abnormal enamel phenotype is currently unknown. In the present study we addressed this question by explanting fetal wild-type and Slc4a4-null mandibles into healthy host kidney capsules to study enamel formation in the absence of systemic acidemia. Mandibular E11.5 explants from NBCe1^−/− mice, maintained in host kidney capsules for 70 days, resulted in teeth with enamel and dentin with morphological and mineralization properties similar to cultured NBCe1^+/+ mandibles grown under identical conditions. Ameloblasts express a number of proteins involved in dynamic changes in H⁺/base transport during amelogenesis. Despite the capacity of ameloblasts to dynamically modulate the local pH of the enamel matrix, at least in the NBCe1^−/− mice, the systemic pH also appears to contribute to the enamel phenotype. Extrapolating these data to humans, our findings suggest that in patients with NBCe1 mutations, correction of the systemic metabolic acidosis at a sufficiently early time point may lead to amelioration of enamel abnormalities.

Breast-feeding duration: influence on taste acceptance over the first year of life

Early feeding experiences, e.g. related to milk feeding, can affect later food and taste preferences. However, consequences of breast-feeding on taste acceptance are under-investigated. The objective of the present study was to examine the impact of exclusive breast-feeding duration (DEB) on taste acceptance at 6 and 12 months in the same infants (n122). Mothers recorded the DEB. Acceptance of solutions of each of the five basic tastes relative to water was evaluated in the laboratory at 6 and 12 months by the ingestion ratio (IR). Kendall correlations were calculated between the DEB and the IR. Only 16 % completed at least 6 months of exclusive breast-feeding; 79 % had begun complementary feeding by 6 months. At 6 months, infants preferred sweet, salty and umami solutions over water and were indifferent to sour and bitter solutions. The longer an infant was breast-fed, the more s/he accepted the umami solution at 6 months. At 12 months, infants preferred sweet and salty solutions over water and were indifferent to sour, bitter and umami solutions. The relationship between the DEB and acceptance of the umami solution was not observed at 12 months. No relationship was observed between the DEB and sweet, salty, sour and bitter taste acceptance at 6 or 12 months. The association between the DEB and umami taste acceptance at 6 months may relate to the higher glutamate content of human milk compared with formula milk. Beyond the acknowledged metabolic benefits of breast-feeding, this suggests that prolonged breast-feeding could also be associated with an impact on sensory preference at the beginning of complementary feeding.

[Impact of fetal urinary ascites on serum beta2 microglobuline in obstructive uropathies: a case report]

We report a posterior urethral valves case diagnosed at 33 week's gestation on a fetus presenting with anamnios and urinary ascites. In this fetus, the serum beta2 microglobuline rate was high, suggesting a very poor renal prognosis. At 1-year-old, the creatinine rate is nearly normal. In case of urinary ascites, the serum beta2 microglobuline rate could be improved in relation with the transperitoneal reabsorption of this protein.

Expression of ammonia transporter family members, Rh B glycoprotein and Rh C glycoprotein, in the developing rat kidney

Ammonia metabolism is a primary component of acid-base homeostasis but is incompletely developed at time of birth. Rh B glycoprotein (Rhbg) and Rh C glycoprotein (Rhcg) are recently recognized ammonia transporter family members expressed in the mammalian kidney. This study's purpose was to establish the expression and localization of Rhbg and Rhcg during kidney development. We examined kidneys from fetal days 16 (E16), 18 (E18), and 20 (E20), and from the first 21 days of postnatal development. Rhbg was expressed initially at E18, with expression only in the connecting tubule (CNT); at E20, Rhbg was expressed in both the CNT and the medullary collecting duct (MCD). In contrast, Rhcg was first expressed at E16 with basal expression in the ureteric bud; at E18, it was expressed in a subset of CNT cells with an apical pattern, followed by apical and basolateral expression in the MCD at E20. In the cortex, Rhbg and Rhcg expression increased in the CNT before expression in the cortical collecting duct during fetal development. In the MCD, both Rhbg and Rhcg expression was initially in cells in the papillary tip, with gradual removal from the tip during the late fetal period and transition during the early neonatal period to an adult pattern with predominant expression in the outer MCD and only rare expression in cells in the initial inner MCD. Double-labeling with intercalated cell-specific markers identified that Rhbg and Rhcg were expressed initially in CNT cells, CNT A-type intercalated cells and non-A, non-B intercalated cells, and in MCD A-type intercalated cells. We conclude that expression of Rhbg and Rhcg parallels intercalated cell development and that immature Rhbg and Rhcg expression at birth contributes to incomplete ammonia excretion capacity.

Fetal cystoscopy for severe lower urinary tract obstruction--initial experience of a single center

OBJECTIVE

To report the experience with fetal cystoscopy and laser fulguration of posterior urethral values (PUV) for severe lower urinary tract obstruction (LUTO).

METHODS

Between July 2006 and December 2008, fetal cystoscopy was offered to 23 patients whose fetuses presented with severe LUTO, favorable urinary analysis and gestational age <26 weeks. Fetal urinary biochemistry was evaluated before and after cystoscopy. All infants were followed 6-12 months after birth. Abnormal renal function was defined when serum creatinine higher than 50 micromol/L (2 Standard Deviation) or the necessity of dialysis or renal transplantation. Autopsy was always performed whenever fetal or neonatal deaths occurred.

RESULTS

Eleven patients decided to undergo fetal therapy and 12 elected to continue with expectant observation. There was no difference between both groups in gestation age at diagnosis and referral examinations. Urethral atresia was diagnosed in 4/11 (36.4%) fetuses by fetal cystoscopy. At 26 weeks, fetuses that were managed expectantly presented with worse urinary biochemistry results (p < 0.05). Survival rates and percentage of infants with normal renal function were significantly higher in the cystoscopic group than in the expectant group (p < 0.05).

CONCLUSIONS

Percutaneous fetal cystoscopy is feasible using a thinner special cannula for prenatal diagnosis and therapy of LUTO. Prenatal laser ablation of the PUV under cystoscopy may prevent renal function deterioration improving postnatal outcome.

Bartter syndrome prenatal diagnosis based on amniotic fluid biochemical analysis

Bartter syndrome is an autosomic recessive disease characterized by severe polyuria and sodium renal loss. The responsible genes encode proteins involved in electrolyte tubular reabsorption. Prenatal manifestations, mainly recurrent polyhydramnios because of fetal polyuria, lead to premature delivery. After birth, polyuria leads to life-threatening dehydration. Prenatal genetic diagnosis needs an index case. The aim of this study was to analyze amniotic fluid biochemistry for the prediction of Bartter syndrome. We retrospectively studied 16 amniotic fluids of Bartter syndrome-affected fetuses diagnosed after birth, only six of them being genetically proven. We assayed total proteins, alpha-fetoprotein, and electrolytes and defined a Bartter index corresponding to the multiplication of total protein and of alpha-fetoprotein. Results were compared with two control groups matched for gestational age-non-Bartter polyhydramnios (n = 30) and nonpolyhydramnios (n = 60). In Bartter syndrome, we observed significant differences (p < 0.0001) for protein amniotic fluid levels when compared with the two control groups (1.55 g/L, 3.9 g/L, and 5.2 g/L, respectively) and low Bartter index (0.16, 0.82, and 1.0, respectively). No statistical difference was observed for electrolytes. In conclusion, Bartter syndrome can be prenatally suspected on amniotic fluid biochemistry (sensitivity 93% and specificity 100%), allowing appropriate management before and after birth.

Developmental changes in the acceptance of the five basic tastes in the first year of life

Taste is a major determinant of children's food preferences, but its development is incompletely known. Thus, exploring infants' acceptance of basic tastes is necessary. The first objective was to evaluate the acceptance of tastes and their developmental changes over the first year. The second objective was to compare acceptance across tastes. The third objective was to evaluate global taste reactivity (within-subject variability of acceptance across tastes). Acceptance of sweet, salty, bitter, sour and umami tastes was assessed in three groups of forty-five 3-, 6- and 12-month-old infants using observations based on ingestion and liking scored by the experimenter. For each taste, four bottles were presented (water, tastant, tastant, water). Acceptance of each taste relative to water was defined using proportional variables based on ingestion or liking. Acceptance over the first year only evolved for sweet taste (marginal decrease) and salty taste (clear increase). At each age, sweet and salty tastes were the most preferred tastes. Reactions to umami were neutral. Sour and bitter tastes were the least accepted ones but rejected only when considering liking data. Ingestion and liking were complementary to assess taste acceptance. However, congruency between these measures rose during the first year. Moreover, with increasing age, reactions were more and more contrasted across tastes. Finally, during the first year, inter-individual variability increased for all tastes except salty taste. By enhancing knowledge of the development of taste acceptance the present study contributes to understand better food behaviour in infancy, the foundation of food behaviour in adulthood.

Fetal obstructive uropathy: is urine sampling useful for prenatal counselling?

OBJECTIVES

To evaluate whether fetal urinary sodium and chloride provide clinically useful information in addition to ultrasound in bilateral obstructive uropathy.

METHODS

Sonographic features and urinary concentrations of sodium and chloride were evaluated in fetuses with bilateral obstructive uropathy. After a minimum of 12 months of postnatal follow-up, cases that developed increased serum creatinine (greater than 50 micromol/L) were compared with those that did not.

RESULTS

Of the cases studied, 16/35 died perinatally, all showing anamnios and markedly elevated urinary electrolytes. Of the survivors, ten maintained normal postnatal serum creatinine, whereas nine did not. The frequency of reduced amniotic fluid/olygohydramnios was higher in cases that developed increased serum creatinine (four out of nine) than in those that did not (nil). Sodium above the 95th percentile was 100% specific and 44% sensitive to predict an increased serum creatinine during early infancy, while chloride above the 95th percentile was 70% specific and 56% sensitive. All seven cases in which urinary sodium was elevated and/or amniotic fluid volume was reduced developed renal failure.

CONCLUSION

Urine sampling slightly improved renal function prediction, but this must be balanced against its fetal risks.

Prenatal diagnosis of megacystis-microcolon-intestinal hypoperistalsis syndrome: contribution of amniotic fluid digestive enzyme assay and fetal urinalysis

OBJECTIVES

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) is a usually lethal disease during the first year of life. There is no specific ultrasound prenatal diagnosis and no identified genetic locus. The value of amniotic fluid digestive enzyme assay and fetal urine biochemistry in the prediction of MMIHS was analysed.

METHODS

Retrospective study of 14 MMIHS cases. Amniotic fluid digestive enzymes and fetal urine biochemistry were compared in MMIHS and megabladder (63 and 264 cases respectively).

RESULTS

Abnormal amniotic fluid digestive enzyme profile (vomiting of bile or digestive secretion leakage) was observed in 8/10 MMIHS cases. These profiles were observed in 7/63 controls; 80% sensitivity (95%CI = 55%-100%); 89% specificity (95%CI = 81%-96%). Fetal urinalysis was normal in 12/12 MMIHS cases except high calcium (>0.6 mmol/l). This profile was observed in 33/264 megabladder control cases; 100% sensitivity; 98.7% specificity (95%CI = 83.5%-91.5%).

CONCLUSION

For the first time, we propose a prenatal diagnosis of MMIHS based on amniotic fluid digestive enzyme assay and on fetal urinalysis.

Syndrome d’insuffisance rénale fœtale

Some anomalies of the kidney and urinary tract evolving in utero may compromise the renal function in the newborn. Early therapeutic options do exist, especially in obstructive nephropathies. The decision depends on a correct evaluation of the foetal enal function and prognosis, which is based on a range of methods: ultrasound echography, biochemical analysis of foetal urine, and, more recently, foetal serum markers such a beta-2 micro globulin. These methods are reviewed.

Fetal renal impairment

Renal function in utero deals chiefly with urine production rather than the excretion of metabolites, which are cleared by the placenta. Fetal renal impairment (FRI) in bilateral renal disease thus presents as oligohydramnios or anhydramnios; this can lead to lung hypoplasia and early neonatal death. As in the adult, FRI can be divided into prerenal, renal and postrenal causes. Causes of prerenal FRI include intrauterine growth restriction, unbalanced intertwin transfusion in monochorionic twins and maternal drug ingestion. Bilateral renal agenesis, multicystic dysplasia and both the autosomal dominant and recessive forms of polycystic kidney disease are examples of renal causes, whereas postrenal etiologies are usually caused by lower urinary tract obstruction (LUTO). When both kidneys are affected and there is severe mid-trimester oligohydramnios, the prognosis is poor. Although animal studies have shown that prolonged LUTO leads to lung hypoplasia and renal damage, and that decompression of the fetal kidney in early pregnancy restores fetal pulmonary and renal function, the value of fetal therapy such as vesico-amniotic shunting remains controversial, with a high procedure-related complication rate and a high incidence of end-stage renal failure in childhood. Fetal cystoscopic treatment of posterior urethral valves in utero may obviate some of these difficulties but remains an investigational procedure.

Recovery after relief of fetal urinary obstruction: morphological, functional and molecular aspects

The effects of obstruction [urinary tract obstruction (UTO)] and relief on renal development were examined in an experimental model in the fetal lamb. Bladder outlet obstruction was performed at 60 days of gestation; relief was performed by vesicoamniotic shunting at 90 days of gestation. Studies were carried out in obstructed (OF60; n = 11), shunted (SF; n = 5), and control fetuses (CF; n = 11) at 120 days of gestation. Fetal UTO produced either hydronephrosis (64%) or dysplasia (36%); dysplasia was always associated with a reduction in the number of glomeruli [950 +/- 99 (dysplasia) vs. 1,852 +/- 249 (CF) glomeruli/section]. Obstructed fetuses had lower creatinine clearance [0.76 +/- 0.41 (OF60) vs. 0.96 +/- 0.21 (CF) ml x min(-1) x kg(-1)], higher sodium fractional excretion [17.2 +/- 20.3 (OF60) vs. 2.4 +/- 3.7% (CF)], and higher urinary concentration [80 +/- 30 (OF60) vs. 43 +/- 22 (CF) micromol/l] than controls. In SF, the number of glomeruli was increased at 120 days of gestation (1,643 +/- 106 glomeruli/section) compared with nondiverted fetuses (1,379 +/- 502 glomeruli/section), and the temporal pattern of PAX2, disrupted after obstruction, was restored. In conclusion, early fetal UTO leads to either renal hydronephrosis with normal glomerular development or dysplasia with a decreased number of glomeruli; in utero urine diversion performed before the end of nephrogenesis may allow a reversal of the glomerulogenesis arrest observed.

The clinical chemistry of inorganic sulfate

Although inorganic sulfate is an essential and ubiquitous anion in human biology, it is infrequently assayed in clinical chemistry today. Serum sulfate is difficult to measure accurately without resorting to physicochemical methods, such as ion chromatography, although many other techniques have been described. It is strongly influenced by a variety of physiological factors, including age, diet, pregnancy, and drug ingestion. Urinary excretion is the principal mechanism of disposal for the excess sulfate produced by sulfur amino acid oxidation, and the kidney is the primary site of regulation. In renal failure, sulfoesters accumulate and hypersulfatemia contributes directly to the unmeasured anion gap characteristic of the condition. In contrast, sulfate in urine is readily assayed by a number of means, particularly nephelometry after precipitation as a barium salt. Sulfate is most commonly assayed today as part of the clinical workup for nephrolithiasis, because sulfate is a major contributor to the ionic strength of urine and alters the equilibrium constants governing saturation and precipitation of calcium salts. Total sulfate deficiency has hitherto not been described, although genetic defects in sulfate transporters have been associated recently with congenital osteochondrodystrophies that may be lethal. New insights into sulfate transport and its hormonal regulation may lead to new clinical applications of sulfate analysis in the future.

Fetal serum beta2-microglobulin predicts postnatal renal function in bilateral uropathies

BACKGROUND

Predicting postnatal renal function is crucial for the prenatal evaluation of fetal bilateral uropathies. Prenatal ultrasound can identify intrauterine terminal renal failure, but is not sensitive enough to identify those infants who would survive with an impaired renal function. Because it reflects fetal glomerular filtration, fetal serum beta2-microglobulin is a potential predictor of postnatal renal function.

METHODS

Fetal serum beta2-microglobulin (beta2m) was assayed in 61 cases of bilateral or low obstructive uropathy, 74 controls, and 17 cases of bilateral renal agenesis, and was correlated with renal function.

RESULTS

Fetal serum beta2m was 3.2 mg/L (range 1.5 to 4.7) in controls (N = 74), 9.5 mg/L (range 6.7 to 11.3) in bilateral renal agenesis (N = 17), 7 mg/L (5.1 to 10.6) in uropathy in which terminal renal failure resulted in termination of pregnancy (N = 26), and 3.7 mg/L (range 2.3 to 11.2) in live births with uropathy (N = 35). In the latter subgroup, fetal serum beta2m was significantly and positively correlated (r2 = 0.91) with postnatal serum creatinine. All survivors with a postnatal serum creatinine < or =50 micromol/L ha a fetal serum beta2m lower than 5 mg/L. Four of 6 survivors with a postnatal serum creatinine> 50 micromol/L had a fetal serum beta2m greater than 5 mg/L.

CONCLUSION

Fetal serum beta2-microglobulin is a marker for renal function and predicts postnatal serum creatinine in bilateral or low fetal obstructive uropathy.

Evaluation of the fetal kidney maturation by assessment of amniotic fluid alpha-1 microglobulin levels

OBJECTIVE

To evaluate the fetal renal maturation by assessment of amniotic fluid microproteins and to show these proteins originate from fetal urine.

STUDY DESIGN

Amniotic fluid proteins (total protein, albumin, high molecular weight protein-HMWP, low molecular weight protein-LMWP, alpha(1)-microglobulin and beta(2)-microglobulin) were determined in 39 pregnant women at delivery and by amniocentesis in 30 pregnant women. These values were compared with first urine values of neonates with the same gestational age.

RESULTS

Albumin was the largest protein component in the amniotic fluid. LMWP showed an increase in the amniotic fluid until the end of the second trimester; and as pregnancy advanced a progressive decrease occurred in parallel to fetal renal maturation. After 26 weeks' gestation, a strong correlation was identified between LMWP levels and alpha(1)-microglobulin, and between LMWP and beta(2)-microglobulin. No significant difference was detected between LMWP levels in the first urine of the neonates and in amniotic fluids.

CONCLUSION

Microproteins in the fetal urine are of fetal origin. Fetal renal maturation can be evaluated by measuring microproteins in the amniotic fluid. Fetal renal maturation is best reflected by alpha(1)-microglobulin.

Outcome of posterior urethral valves: to what extent is it improved by prenatal diagnosis?

PURPOSE

To assess the impact of prenatal diagnosis and evaluation on the outcome of posterior urethral valves we studied all cases of valves detected prenatally, including cases of pregnancy termination due to posterior urethral valves.

MATERIALS AND METHODS

Between 1989 and 1996, 30 neonates with prenatally detected posterior urethral valves were treated at our hospital. The prenatal parameters analyzed were age of gestation at diagnosis, ultrasonographic appearance of renal parenchyma and amniotic fluid volume. Fetal urine was analyzed in 9 cases. We reviewed the outcome of 10 neonates treated for posterior urethral valves which were not diagnosed prenatally during the same period.

RESULTS

Of the 30 neonatal survivors 6 (20%) had renal failure, including end stage renal disease in 2, after a mean followup of 4 years. Renal failure developed in 2 of 5 cases detected before 24 weeks of gestation, in 1 of 6 with oligohydramnios and in 2 of 5 with abnormal parenchymal renal ultrasound. Normal parenchymal ultrasound and amniotic volume could not predict for good outcome. Renal failure developed in 2 of 7 cases predicted by fetal urinalysis as good prognosis and in 1 of 2 cases predicted as poor prognosis. Pregnancy was terminated for posterior urethral valves in 5 cases based on prenatal criteria of severe renal impairment. Considering these cases as poor outcome, the rate of poor prognosis increased from 20 to 31%. Among the 10 neonates without a prenatal diagnosis of posterior urethral valves renal failure developed in 2 (20%), including end stage renal disease in 1.

CONCLUSIONS

When negative parameters were absent and/or fetal urine predicted good outcome there were no cases of end stage renal disease in early infancy, which was a significant help in parent counseling. The predictive value of the currently available prenatal parameters needs to be updated with larger series specifically dealing with posterior urethral valves. According to the current data, the outcome of posterior urethral valves is not yet significantly improved by prenatal diagnosis.

Fetal urinary tract abnormalities. Natural history, pathophysiology, and treatment

Urologic abnormalities are commonly detected on routine obstetric sonographic examinations. The progressive nature and potential reversibility of obstructive urologic anomalies have led to interest in in utero treatment of these lesions. Over 90% of obstructive urologic lesions do not need treatment until after birth. For a select group of patients, antenatal treatment may improve postnatal renal and pulmonary function. When indicated, minimally invasive nephroamniotic or vesicoamniotic stenting is the preferred method of treatment.