Evaluation of fetal renal function: unreliability of fetal urinary electrolytes

Definition, diagnosis and management of fetal lower urinary tract obstruction: consensus of the ERKNet CAKUT-Obstructive Uropathy Work Group

Fetal lower urinary tract obstruction (LUTO) is associated with high mortality and postnatal morbidity caused by lung hypoplasia and impaired kidney function. Specific diagnostic features that can guide clinical approach and decisions are lacking; thus, the European Reference Network for Rare Kidney Diseases established a work group to develop recommendations regarding the clinical definition, diagnosis and management of prenatally detected LUTO. The work group recommends the use of antero-posterior diameter of renal pelvis as the most reliable parameter for suspecting obstructive uropathies and for suspecting prenatal LUTO in the presence of fetal megacystis. Regarding prenatal and postnatal prognosis of fetuses with LUTO, the risk of fetal and neonatal death depends on the presence of oligohydramnios or anhydramnios before 20 weeks' gestation, whereas the risk of kidney replacement therapy cannot be reliably foreseen before birth. Parents of fetuses with LUTO must be referred to a tertiary obstetric centre with multidisciplinary expertise in prenatal and postnatal management of obstructive uropathies, and vesico-amniotic shunt placement should be offered in selected instances, as it increases perinatal survival of fetuses with LUTO.

Renal development in the fetus and premature infant

Congenital abnormalities of the kidney and urinary tract (CAKUT) are one of the leading congenital defects to be identified on prenatal ultrasound. CAKUT represent a broad spectrum of abnormalities, from transient hydronephrosis to severe bilateral renal agenesis. CAKUT are a major contributor to chronic and end stage kidney disease (CKD/ESKD) in children. Prenatal imaging is useful to identify CAKUT, but will not detect all defects. Both genetic abnormalities and the fetal environment contribute to CAKUT. Monogenic gene mutations identified in human CAKUT have advanced our understanding of molecular mechanisms of renal development. Low nephron number and solitary kidneys are associated with increased risk of adult onset CKD and ESKD. Premature and low birth weight infants represent a high risk population for low nephron number. Additional research is needed to identify biomarkers and appropriate follow-up of premature and low birth weight infants into adulthood.

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

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

Glomerular filtration rate and urine osmolality in unilateral ureteropelvic junction obstruction

Background:

Renal maldevelopment, interstitial fibrosis, ischemic atrophy, decreased glomerular filtration rate (GFR), and renal blood flow (RBF) are inevitable consequences of chronic kidney obstruction that only partially improve after early intervention. There are only few studies that evaluated urine osmolality in affected kidney and its correlation with short-term outcome.

Materials and Methods:

Thirty patients (age<1 year) with unilateral ureteropelvic junction obstruction (UUPJO) were enrolled in this study. UUPJO was confirmed using Technetium 99 isotope scans and the patients were indicated to be operated afterward. Urine and blood samples were obtained before, 24, 48, and 72 h after the surgery. The serum level of blood urea nitrogen, creatinine, and glucose were measured. GFR, urine osmolality (measured and calculated), and urine specific gravity were determined too.

Results:

Cortical thickness of hydronephrotic kidney was significantly increased 6 months after the surgery. GFR was significantly increased 72-h postsurgery compared to before operation.

Neither means of calculated nor of measured urine osmolalities were significantly different in various stages. The last calculated urine osmolality (72 h) had significant correlation with the last measured osmolality (72 h); r=0.962, P=0.0001. The last GFR (72 h) had positive significant correlation with GFR before the surgery and GFRs at 24 and 48 h postsurgery.

Using regression tests, only the before surgery GFR was the predictor of the last GFR(72 h).

Conclusion:

In UUPJO the measured and calculated urine osmolality of the affected kidney did not differ. In addition, GFR before surgery should be considered as the predictor of the GFR shortly after repair.

Ultrasound evaluation of prognosis in fetuses with posterior urethral valves

PURPOSE

The aim of this study was to evaluate the ability of prenatal ultrasound markers to predict postnatal renal prognosis in fetuses with posterior urethral valves.

METHODS

Medical files on fetuses with prenatal diagnosis of posterior urethral valves from 2000 to 2006 were reviewed retrospectively. Data from prenatal follow-up included gestational age at diagnosis, ultrasound renal parenchyma evaluation, and presence and time of oligohydramnios onset. Prenatal parameters studied were correlated to postnatal renal function.

RESULTS

Thirty-one male fetuses were included. Six pregnancies were terminated. Of the remaining 25 pregnancies that were continued, 4 children had abnormal creatine and 21 normal creatinine levels at follow-up. Presence and time of oligohydramnios onset did not differ between groups (P = .43). Ultrasound detected bilateral renal abnormalities in 3 fetuses (75%) with altered renal function, and 10 fetuses (55%) with normal creatinine, at follow-up.

CONCLUSIONS

None of the ultrasound parameters evaluated were able to reliably predict postnatal renal function.

Prenatal management of urogenital disorders

Antenatal sonography has markedly increased the detection of urogenital anomalies, including those conditions that lead to significant morbidity and mortality. Prenatal intervention is feasible to arrest and sometimes reverse the sequelae of bladder outlet obstruction but not necessarily renal damage. Myelomeningoceles, the most severe form of spina bifida, can be corrected in utero, with improvements in hydrocephalus seen along with a decreased incidence of ventricular shunting postnatally. Medical therapy to prevent virilization associated with congenital adrenal hyperplasia has been successful, with improved ability to detect its presence prenatally now possible. As further techniques evolve to correct underlying disease processes, it becomes important to critically assess the therapies, particularly with long-term outcome data.

Posterior urethral valve: Outcome of antenatal intervention

INTRODUCTION AND AIM

Antenatal treatment of obstructive uropathy, although widely performed, remains controversial. This study evaluated the long-term outcome of managing patients with posterior urethral valves (PUV), highlighting the effect of antenatal vesicoamniotic shunt placement for patients who underwent fetal surgery.

METHODS

The medical records of 58 patients with PUV were retrospectively reviewed from June 1998 to June 2004. On the basis of prenatal assessment of sonographic findings and serial urinary electrolytes and protein measurements, patients were divided into two groups: group 1 comprised patients who had antenatal vesicoamniotic shunt placement whereas group 2 comprised patients who underwent postnatal surgical correction of PUV. Their outcomes and long-term results were evaluated.

RESULTS

Patients were followed up from 6 months to 6(1/2) years (mean 3.9 years). Group 1 included 12 patients who had vesicoamniotic shunt placement and were confirmed postnatally to have PUV. Four patients out of 12 died (33.3%); three out of the eight living patients had perinatal complications. Of the eight living patients, three (37.5%) underwent valve ablation and five (62.5%) underwent urinary diversion (three vesicostomies and two cutaneous ureterostomies). Renal function returned to normal in only four patients (50%). Radiological abnormalities (hydronephrosis and/or reflux) resolved in three (37.5%) patients, was downgraded in one (12.5%) patient and persisted in four patients (50%). Group 2 included 46 patients who were treated postnatally. Thirty-five patients (76%) underwent primary valve ablation, while 11 (24%) underwent urinary diversion (seven vesicostomies, four cutaneous ureterostomy and one pyelostomy). Renal function returned to normal in all patients who underwent valve ablation, except in three, while renal function returned to normal in only three of 11 patients who underwent urinary diversion. Radiological hydronephrosis and/or reflux resolved in 28 patients (60.9%), was downgraded in six patients (13%) and persisted in 12 patients (26.1%).

CONCLUSIONS

Antenatal vesicoamniotic shunt placement makes no difference to the outcome and long-term results of patients with PUV and debate about its efficacy on renal outcome remains. Primary valve ablation is the keystone of treatment for patients with PUV that might achieve the primary goal of nephron preservation. The lowest creatinine concentration in the first year of life is the most appropriate predictor of future renal function.

Early bladder wall changes after creation of obstructive uropathy in the fetal lamb

Vesico-amniotic shunting of obstructive uropathy in fetal lambs produced a thick-walled, poorly compliant bladder. We report the early histological changes in the obstructed bladder wall. We created an obstructive uropathy in fetal lambs at 60 days gestation by ligating the urethra and urachus. Vesicostomy or vesico-amniotic shunt tube insertion and biopsy of the bladder wall were performed 21 days later. The fetuses were delivered at term (145 days) and the kidneys and bladder sampled for histology. Colloidal iron (Col Fe), and alpha-smooth muscle actin (alpha-SMA) immunohistochemical stains were used for these samples. Seventeen fetuses were shunted with 15 biopsies taken at that time. Six (shunt failure or missed urachal ligation) were excluded. All biopsies taken at shunting had positive Col Fe and alpha-SMA. Term lambs had mild multicystic dysplastic kidney (MCDK) in five, severe MCDK in two, and hydronephrosis in four. All bladders had small volume and were severely fibrotic. Fetal shunt operations 3 weeks after the creation of obstructive uropathy provided partial preservation of renal histology but did not preserve normal bladder histology. We suggest that the high hyaluronic acid synthesis activity or hyperplasia of the myofibroblasts in the dilated fetal bladder wall at the time of shunting results in irreversible damage to the developing bladder muscle and fibrosis.

Outcome of fetal renal pelvic dilatation diagnosed during the third trimester

OBJECTIVES

The aim of this study was to evaluate renal function and the need for postnatal treatment--antibiotic therapy and/or surgery--in relation to the grade of fetal renal pelvic dilatation (RPD) found on third-trimester ultrasound examination.

METHODS

The retrospective study included 78 children, born between 1995 and 2000, with 115 dilated fetal renal pelvic units. The children were allocated to three groups based on pelvic anteroposterior diameter (APD) detected on third-trimester ultrasound: APDs of 7-9.9 mm, 10-14.9 mm and > or = 15 mm were classified as mild dilatation, moderate hydronephrosis and severe hydronephrosis, respectively. Renal function was assessed by scintigraphy.

RESULTS

None of the 20 children with mild dilatation experienced a urinary tract infection (UTI) or underwent surgery; two had associated renal or urinary tract abnormalities. In contrast, five out of 22 (23%) children with moderate hydronephrosis and 23 out of 36 (64%) with severe hydronephrosis had either a UTI or required surgery (P < 0.001); associated abnormalities were also more common (6 out of 22 and 15 out of 36, respectively). There was no significant correlation between the grade of antenatal RPD and postnatal ipsilateral renal function.

CONCLUSIONS

The need for postnatal treatment increased significantly with the grade of antenatal RPD. Children with antenatal mild dilatation were discharged early from follow-up whereas those with moderate and severe fetal hydronephrosis needed close follow-up by a multidisciplinary team.

Diagnosis and outcome of fetal lower urinary tract obstruction in the northern region of England

OBJECTIVE

We reviewed the prenatal and postnatal management of fetal lower urinary tract obstruction (LUTO) in a large geographically defined population.

METHODS

The records of 113 cases of LUTO seen over a 14-year period were examined. The predictive accuracy of prenatal findings for chronic renal failure (CRF) and a comparison of prenatal-suspected and non-suspected cases were made.

RESULTS

The incidence of LUTO was 2.2 in 10 000 births. During the study period, prenatal detection improved from 33 to 62%. Sensitivity of prenatal ultrasound detection of renal dysplasia and fetal urinary sodium, calcium, and beta2-microglobulin for CRF or renal dysplasia on autopsy were 59, 33, 66, and 63% respectively. Compared to undetected cases, those detected prenatally had higher mortality and a higher rate of CRF at 24 months (17% vs 57%, p < 0.01).

CONCLUSION

Our observations confirm the poor prognosis associated with fetal LUTO. The value of serial fetal urine biochemistry, other prenatal predictors of postnatal renal function, and the benefits of vesicoamniotic shunting require larger series and longer follow-up.

Initial and long-term management of posterior urethral valves

Posterior urethral valves are the most common cause of congenital obstructive uropathy, resulting in renal failure in childhood. Nowadays, in most cases, diagnosis is suggested by antenatal ultrasound. However, antenatal intervention has not resulted in a significantly improved outcome. Endoscopic valve ablation is the initial treatment in most of these neonates, but others procedures, like vesicostomy or ureterostomy, can also be justified in some particular cases in order to improve renal function prognosis. Different factors like bladder dysfunction, VUR, polyuria and proteinuria, can be responsible for the slow and progressive deterioration in renal function that some of these patients show over the years. By treating them all, we may prevent or delay the onset of end stage renal disease.

Prenatal management of urogenital disorders

Antenatal sonography has increased the detection of urogenital anomalies markedly, including conditions that lead to significant morbidity and mortality. Prenatal intervention is feasible to arrest and sometimes reverse the sequelae of bladder-outlet obstruction, but not necessarily renal damage. Myelomeningoceles, the most severe form of spina bifida,can be corrected in utero, with improvements in hydrocephalus and a decreased incidence of ventricular shunting postnatally. Medical therapy to prevent virilization associated with congenital adrenal hyperplasia has been successful, with improved ability to detect its presence prenatally. As techniques evolve to correct underlying disease processes,it becomes important to assess the therapies critically, particularly with long-term outcome data.

Prenatal intervention for urinary obstruction and myelomeningocele

Widespread use of ultrasonography has resulted in an increase in the recognition of fetal hydronephrosis. The enthusiasm that accompanied early interventions has been tempered by the experience and results obtained over the past 2 decades. The goal has remained the same: to identify patients with serious prenatal obstruction and to identify those which may benefit from intervention. Myelomeningocele remains a devastating congenital anomaly. Fetal and experimental studies suggested that patients with myelomeningocele could benefit from prenatal intervention. Advances in technology and perinatal management have made intervention for more complex malformations such as myelomeningocele possible. This article will review current knowledge and will detail rational management for the management of prenatal hydronephrosis. The current state of antenatal myelomeningocele repair and the urologic implications will be described as well.

Perinatal outcome in fetuses with megacystis in the first half of pregnancy

OBJECTIVE

To present the outcome of a consecutive series of 19 fetuses referred to our center for megacystis in the first half of the pregnancy.

STUDY DESIGN

Retrospective analysis.

METHODS

19 cases of early fetal megacystis were reviewed. Inclusion criteria were the visualization of an enlarged bladder with a maximum longitudinal diameter >10 mm and a gestational age of no more than 19 weeks.

RESULTS

The median gestational age at diagnosis was 16 weeks (range 12-19 weeks). The median maximum longitudinal diameter of the fetal bladder at the time of diagnosis was 21 mm (range 11-35 mm). The fetal megacystis was associated with another extra renal anomaly in six cases (30%). There was no fetus with abnormal karyotype. Termination of pregnancy was performed in 11 cases because of the severity of the renal disease. One spontaneous intrauterine death occurred. A vesicoamniotic shunt was inserted in three cases, two of which died in utero. The surviving fetus that was shunted died in the neonatal period from acute renal failure. In the remaining four fetuses, resolution of the megacystis occurred spontaneously (n = 2) or following serial single-needle aspiration (n = 2). One of these had renal insufficiency requiring kidney transplantation.

CONCLUSION

The outcome of fetuses with early obstructive uropathy is poor, with or without in utero therapy. Pathophysiology, clinical presentation and outcome of fetuses with early uropathy may differ from those previously described in the latter part of pregnancy.

Fetal surgery for posterior urethral valves: long-term postnatal outcomes

OBJECTIVE

Fetal intervention for obstructive uropathy was first performed at the University of California, San Francisco in 1981. Indications for treatment were bilateral hydronephrosis with oligohydramnios. Preintervention criteria included fetal urinary electrolytes with beta-microglobulin levels, karyotyping, and detailed sonography specifically looking for renal cortical cysts. We reviewed the outcomes of children who underwent fetal intervention with specific long-term follow-up in patients who were found postnatally to have posterior urethral valves.

METHODS

A retrospective review of the University of California, San Francisco fetal surgery database was performed for patients with a prenatal diagnosis of obstructive uropathy. Medical records from 1981 to 1999 were reviewed. Long-term follow-up was documented if the cause of the urinary tract obstruction was posterior urethral valves. We collected data points, focusing on time and type of intervention, fetal urinary electrolytes, appearance of fetal kidneys, present renal function, length of follow-up, and present status of the urinary tract.

RESULTS

Forty patients were evaluated for fetal intervention; 36 fetuses underwent surgery during this time period. Postnatal confirmation of posterior urethral valves was demonstrated in 14 patients. All patients had favorable fetal urinary electrolytes. Mean gestational age at intervention was 22.5 weeks. The procedures performed included creation of cutaneous ureterostomies in 1, fetal bladder marsupialization in 2, in utero ablation of valves in 2, and placement of vesicoamniotic catheter in 9. Six deaths occurred before term delivery with premature labor and the newborns succumbing to respiratory failure. One pregnancy was terminated electively because of shunt failure and declining appearance of fetal lungs and kidney. The remaining 8 living patients had a mean follow-up of 11.6 years. Chronic renal disease with abnormal serum creatinine was present in 5 patients. Two patients have undergone renal transplantation, and 1 is awaiting organ donation. Five of the 8 living patients have had urinary diversion with vesicostomy, cutaneous ureterostomy, or augmentation cystoplasty with later reconstruction.

CONCLUSIONS

Fetal intervention for posterior urethral valves carries a considerable risk to the fetus with fetal mortality rate of 43%. The long-term outcomes indicate that intervention may not change the prognosis of renal function or be a predictor for possible urinary diversion. Despite all of these patients' having favorable urinary electrolytes, this did not seem to have any implication postnatally. When counseling families about fetal intervention, efforts should be focused on that intervention may assist in delivering the fetus to term and that the sequelae of posterior urethral valves may not be preventable. Fetal surgery for obstructive uropathy should be performed only for the carefully selected patient who has severe oligohydramnios and "normal"-appearing kidneys.

Posterior urethral valves: pre- and postnatal management

Posterior urethral valves are a common problem encountered by pediatric urologists. The diagnosis is most frequently suggested by antenatal screening ultrasound. A variety of pre- and postnatal parameters have been identified to aid in predicting ultimate renal outcome. These prognostic tools are invaluable to the clinician for counseling parents and for choosing appropriate management. Several approaches to the treatment of patients with posterior urethral valves exist, and the ideal strategy is debatable. As technology evolves, more options for early intervention become available. Whether early detection and antenatal intervention improve patient outcome remains to be proven.

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.

Clinical results of fetal obstructive uropathy treated by vesicoamniotic shunting

OBJECTIVES

To report the clinical results of 5 fetuses after a vesicoamniotic shunting procedure (VASP).

METHODS

Between 1995 and 1998, 5 patients (two with prune belly syndrome, one with a cloacal anomaly, one with urethral stenosis, and one with a sacrococcygeal teratoma) underwent VASP using a double-basket catheter. We used the following selection criteria: a fetus without chromosomal defects, with oligohydramnios, and with a predicted good renal function from sequential or single fetal urinalysis (sodium concentration, chloride concentration, and osmolarity at less than 100 mEq/L, less than 90 mEq/L, and less than 210 mOsm, respectively).

RESULTS

The mean gestational age was 20.8 +/- 6.9 weeks at diagnosis, 24.2 +/- 6.0 weeks at VASP, and 30.6 +/- 6.2 weeks at delivery. In our study, 2 of 5 patients survived. One of the patients with prune belly syndrome was 18 months old at last follow-up, with hydrocephalus and a creatinine level of 0.2 mg/dL. The patient with the cloacal anomaly was 4 years old at last follow-up and had signs of clonic convulsion. However, psychomotor development was delayed in both. Of the 3 patients who died, 2 died after birth, and the autopsy determined death was due to pulmonary insufficiency. The patient with urethral stenosis died in utero.

CONCLUSIONS

Although the principal purpose of VASP is to prevent pulmonary hypoplasia and dysfunctional kidneys, VASP was not always effective, as the outcomes were poor in most of our patients. A greater standardization of patient selection and a large cohort study in the future should be considered to assess VASP.

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.

Long-term outcome in children after antenatal intervention for obstructive uropathies

BACKGROUND

Antenatal intervention has been done for fetal obstructive uropathy for over a decade, yet little is known about long-term outcomes. To assess the long-term implications of fetal intervention, we reviewed the outcomes of children who underwent vesicoamniotic shunt placement.

METHODS

We reviewed the clinical outcomes of 14 children who underwent vesicoamniotic shunt placement at our institution and who survived beyond 2 years of age.

FINDINGS

In 1987-96, 34 patients underwent vesicoamniotic shunt placement. 13 died and 21 survived, of whom 17 are now more than 2 years old. Three survivors were lost to follow-up. Mean age at follow-up was 54.3 months (range 25-114). Final diagnoses included prune belly syndrome (seven cases), posterior urethral valves (four), urethral atresia (one), vesicoureteral reflux (one), and megacystis (one). Height was below the 25th percentile in 12 (86%) with seven (50%) below the 5th percentile. Five (36%) had renal failure and had successful transplantation, three (21%) have renal insufficiency, and six (43%) have normal renal function. Seven (50%) are acceptably continent, five (36%) have not yet begun toilet-training, and two (14%) are incontinent. Three of four children with valves needed bladder augmentation.

INTERPRETATION

Antenatal intervention may help those fetuses with the most severe forms of obstructive uropathy, usually associated with a fatal neonatal course. Intervention achieves outcomes similar to less severe cases that are usually diagnosed postnatally.

Follow-up of children after fetal treatment for obstructive uropathy

BACKGROUND

Improvement in the ability to evaluate fetuses with obstructive uropathy, combined with technologic advances, has allowed successful fetal treatment of these conditions in Japan. We analyzed the prenatal and postnatal clinical courses of patients who underwent shunt placement in utero.

METHODS

We treated 6 patients who underwent fetal intervention and were transferred to us for urologic management. Gestational age at detection of abnormalities ranged from 11 weeks to 31 weeks, and fetal intervention was done between 16 weeks and 32 weeks. Excluding 1 infant who was delivered 6 days after the intervention, the mean period between shunt placement and delivery was 17 weeks.

RESULTS

Urologic pathology included prune belly syndrome with urethral hypoplasia in 3 patients, cloacal anomaly in 1, posterior urethral valves in 1, and pelviureteric junction stenosis of a solitary kidney in 1. Four patients required ventilation support in the neonatal period, and 2 of them suffered frequent infections during follow-up. Five patients who underwent vesico-amniotic shunt placement continue to require clean intermittent catheterizations via vesicostomy because of hypoactive detrusors and hypoplastic urethras. After urologic treatment, serum creatinine in 5 patients reached a minimum of less than 0.4 mg/dL at some time during the first year of life. Another patient with a minimum creatinine level of 1.0 mg/dL has moderate renal insufficiency.

CONCLUSION

From our series, it appears that early (before 20 weeks of gestation) shunt placement in severe lower urinary tract obstruction may benefit renal and pulmonary function. However, its efficacy in regard to bladder function remains questionable: shunt placement does not permit regular storage and evacuation, which may be essential for functional bladder development.

Antenatal hydronephrosis. Fetal and neonatal management

As many as 1% of newborn infants have a prenatal diagnosis of hydronephrosis or significant renal pelvic dilation. Hydronephrosis often is caused by nonobstructive conditions. The likelihood of significant urologic pathology is directly related to the size of the fetal renal pelvis, and 90% with an anteroposterior diameter more than 2 cm need surgery or long-term urologic medical care. Following delivery, antibiotic prophylaxis should be administered and a renal sonogram and voiding cystourethrogram should be obtained. If there is grade 3 or 4 hydronephrosis, usually a diuretic renogram is recommended also. Pediatric urologic or pediatric nephrologic consultation usually is helpful in planing evaluation and treatment. Prenatal recognition of hydronephrosis allows neonatal diagnosis and treatment of urologic pathology, preventing complications of pyelonephritis and obstruction.

Successful treatment of fetal megavesica in the first half of pregnancy

OBJECTIVE

Our goal was to assess fetal kidney function in fetuses with megavesica diagnosed during the first half of pregnancy before treatment.

STUDY DESIGN

In a prospective interventional study 9 fetuses with megavesica diagnosed during the first half of pregnancy underwent vesicocentesis. Fetal urine biochemical markers (urine electrolytes, osmolarity, and beta 2-microglobulins) were determined after diagnostic vesicocentesis of the fetal megavesica.

RESULTS

Surprisingly, in four fetuses who underwent sampling at 13 to 18 postmenstrual weeks, vesicocentesis proved both diagnostic and therapeutic. Pregnancy proceeded with normal amniotic fluid volume, a normal-sized urinary bladder with normal dynamics, and normal postnatal renal function. A fifth fetus had trisomy 18. In three of the remaining four fetuses in whom sampling was performed at 16 to 20 postmenstrual weeks, biochemical markers indicated a poor prognosis. In the remaining fetus marginal results of biochemical studies prompted intrauterine treatment, but death from respiratory problems ensued after premature delivery at 31 weeks.

CONCLUSIONS

Fetal megavesica in the first half of pregnancy is an indication for an immediate diagnostic vesicocentesis. This is the first report emphasizing early diagnosis of fetal megavesica with subsequent fetal vesicocentesis and demonstrating that this minimally invasive procedure can be life-saving if performed in early pregnancy.

Serum beta 2-microglobulin in fetuses with urinary tract anomalies

OBJECTIVE

Our purpose was to establish a reference range of fetal serum beta 2-microglobulin, an index of glomerular filtration rate, and to compare the values obtained in fetuses with urinary tract anomalies with this range.

STUDY DESIGN

Serum beta 2-microglobulin was measured in 53 control fetuses at 18 to 39 weeks' gestation and in 14 fetuses with urinary tract anomalies, 9 of which had simultaneous urine sampling.

RESULTS

In controls fetal serum beta 2-microglobulin had a mean value of 3.4 mg/L (95% data intervals 2.0 to 4.9) and did not correlate with gestational age. In the 14 fetuses with urinary tract anomalies beta 2-microglobulin levels were increased overall compared with controls (median Z score 1.7, range -0.1 to 9.2), and this was also the case in the five fetuses with unilateral renal disorders (median Z score 1.7, range -0.1 to 3.8) and in a fetus who underwent vesicoamniotic shunting and had normal renal function at birth. Serum beta 2-microglobulin was normal in 4 fetuses with bilateral urinary tract obstruction and normal function at postnatal follow-up and also in 1 of 5 fetuses with renal failure. In fetuses with bilateral uropathy urinary sodium correlated with serum beta 2-microglobulin levels.

CONCLUSIONS

Increased values of serum beta 2-microglobulin in fetuses with urinary tract anomalies indicate an impaired glomerular filtration rate. The finding of raised concentrations in fetuses with unilateral damage suggests that the compensatory role of the normal kidney is not complete during intrauterine life. Larger series are required to ascertain whether fetal blood sampling is warranted in the antenatal investigation of renal function, especially in view of the close correlation between urinary sodium and serum beta 2-microglobulin levels in fetuses with bilateral obstruction.

Shortcomings in predicting postnatal renal function using prenatal urine biochemistry in fetuses with congenital hydronephrosis

Ten fetuses with hydronephrosis underwent one to seven urine sampling procedures at 23 to 36 weeks' gestation to evaluate renal function. Postnatally, the infants' renal function was assessed by a combination of serum creatinine measurement, ultrasonography and renal scintigraphy. Six infants had pyelo-ureteric junction obstruction, two had megabladder with megaureter, and two had vesico-ureteric reflux. All infants had normal serum creatinine levels at the time of postnatal follow-up, but five of the seven with unilateral involvement had moderate or severe renal damage. Abnormal urinary electrolyte concentrations were found antenatally in only two of them. For the three infants with bilateral hydronephrosis, postnatal evaluation showed moderately or severely damaged kidneys despite prenatal evidence of normal biochemical indexes. Fetal urine electrolyte measurement may be accurate in the diagnosis of renal dysplasia, but its sensitivity is poor in predicting moderate renal dysfunction.

Assessment of serum levels of alpha-1-microglobulin, beta-2-microglobulin, and retinol binding protein in the fetal blood. A method for prenatal evaluation of renal function

The concentrations of alpha-1-microglobulin, beta-2-microglobulin, and retinol binding protein were determined in fetal blood sampled by cordocentesis. The blood values of 126 fetuses without ultrasonographic findings of urinary tract abnormalities as controls were found to be independent of the week of gestation. In nine fetuses affected by a severe bilateral renal dysplasia or agenesis, elevated values of alpha-1-microglobulin but normal values of retinol binding protein were obtained. The authors recommend the determination of alpha-1-microglobulin and, with some restriction, also of beta-2-microglobulin in prenatal renal function diagnosis.

Sequential urinalysis improves evaluation of fetal renal function in obstructive uropathy

OBJECTIVES

The purpose of our study was to determine whether sequential vesicocenteses improve the evaluation of renal damage, compared with single urine sampling in obstructive uropathy.

STUDY DESIGN

A total of 29 fetuses with complete obstructive uropathy underwent a minimum of three sequential complete vesicocenteses at 48- to 72-hour intervals. First and last urine values were analyzed for multiple parameters. The ability of first versus last urine values to detect the presence of renal damage was compared according to postnatal or fetal autopsy information.

RESULTS

Fetuses with minimal renal damage had patterns of decreasing hypertonicity and last urine values below cutoff thresholds indicative of favorable prognosis. Fetuses with significant renal damage had higher initial values and patterns of increasing hypertonicity. For five of six parameters, last urine samples were more predictive of renal damage than first urine samples.

CONCLUSION

Last urine values together with pattern-of-change trend analysis after serial vesicocenteses improve diagnostic precision in fetuses with complete obstructive uropathy.

Management of prenatally detected fetal hydronephrosis

The increased frequency of prenatal ultrasonography has resulted in an increase in the detection of fetal genitourinary abnormalities, many of which are of minimal clinical significance. Severe fetal urinary tract obstruction with associated oligohydramnios results in a recognizable constellation of physical findings, including renal dysplasia, pulmonary hypoplasia, and perinatal death. In selected cases, prenatal intervention to decompress urinary tract obstruction may reestablish amniotic fluid volume, prevent renal damage, and allow normal pulmonary development. After severe renal injury has occurred, intervention is unlikely to improve the prognosis of the affected fetus. Renal function may be analyzed prenatally by ultrasound examination and determination of chemical composition of fetal urine in order to identify fetuses in whom kidney development has not yet been irrevocably damaged and those likely to benefit from prenatal intervention. Postnatal renal evaluation with ultrasonography, voiding cystourethrography, and radionuclide imaging facilitates further characterization of the abnormality detected on prenatal ultrasound examination.

In utero surgical treatment of fetal obstructive uropathy: a new comprehensive approach to identify appropriate candidates for vesicoamniotic shunt therapy

OBJECTIVES

We present a new approach to prenatal evaluation and prediction of renal function and long-term outcomes for fetuses considered candidates for in utero surgery.

STUDY DESIGN

A review of 34 cases of obstructive uropathies was made, with analysis of our approach to prenatal evaluation, the predictive value of urinary electrolytes and protein analysis in identifying renal dysplasia, and the outcomes of cases with and without in utero surgical intervention.

RESULTS

Ten of 11 pregnancies that were terminated had dysplasia; one female had cloacal dysgenesis. In three of eight unshunted cases megacystis resolved after vesicocentesis. Eight of 15 shunted fetuses survived. Of those predicted to have good postnatal outcome, six of six demonstrated good postnatal renal function. Of those predicted to have poor outcomes, two of two had poor postnatal renal function and dysplasia. Seven of 15 shunted fetuses died, four of four predicted to have dysplasia were confirmed, and three died of nonrenal causes.

CONCLUSIONS

Our prenatal approach successfully differentiated fetuses with underlying renal dysplasia from those without irreversible damage who subsequently benefited from in utero vesicoamniotic shunt placement.

Fetal urine biochemistry in the assessment of obstructive uropathy

In 60 fetuses with obstructive uropathy, sodium, total calcium, urea, and creatinine were measured in samples obtained by "urodochocentesis" or pyelocentesis at 16 to 36 weeks' gestation. The patients were retrospectively assigned into two groups on the basis of outcome. Group 1 (n = 20) included infants who either had normal postnatal renal function or absence of prenatal renal dysplasia. Group 2 included infants who either had histologic evidence of renal dysplasia or subsequently developed renal failure. In group 1 the urinary sodium decreased and creatinine increased with gestation, demonstrating maturation in fetal renal function. In group 2 the urinary sodium and calcium were higher and the urinary urea and creatinine were lower than in group 1. The best predictor of outcome was the combination of either high calcium or high sodium with a positive predictive value of 91.3% and negative predictive value of 77.7%. In the antenatal evaluation of obstructive uropathy, fetal urinary biochemistry provides useful information for more accurate counseling of the parents and a rational basis for selecting patients who may benefit from intrauterine therapeutic interventions.