Management of the fetus with congenital hydronephrosis

The reduced number of nephrons with shortening renal tubules in mouse postnatal adverse environment

BACKGROUND

The intrauterine adverse environment during nephrogenesis reduces the nephron number, probably associates with impaired ureteric bud (UB) branching.

METHODS

The kidneys in C57/BL6 mice were irradiated with a single dose of 10 gray (10 Gy) as adverse environment on postnatal day 3 (irradiated PND3 kidneys) after UB branching ceased. The renal functions and pathological findings of irradiated PND3 kidneys were compared with those of non-irradiated control and 10 Gy irradiation on PND14 (irradiated PND14 kidney) from 1 to 18 months.

RESULTS

The number and density of glomeruli in irradiated PND3 kidneys were reduced by 1 month with renal dysfunction at 6 months. The morphologically incomplete glomeruli with insufficient capillaries were involuted by 1 month in the superficial cortex. Reduced tubular numbers and developmental disability with shortening renal tubules occurred in irradiated PND3 kidneys with impaired urine concentration at 6 months. Hypertrophy of glomeruli developed, and occasional sclerotic glomeruli appeared in the juxtamedullary cortex with hypertension and albuminuria at 12 to 18 months.

CONCLUSIONS

The reduced number of nephrons with shortening renal tubules occurred with impaired renal functions in a postnatal adverse environment after cessation of UB branching, and glomerular hypertrophy with occasional glomerulosclerosis developed accompanied with hypertension and albuminuria in the adulthood.

IMPACT

The reduced number of nephrons with shortening renal tubules occurred with impaired renal functions in a postnatal adverse environment after cessation of ureteric bud branching. The reduced number of glomeruli were associated with not only the impaired formation of glomeruli but also involution of morphologically small incomplete glomeruli after an adverse environment. The insufficiently developed nephrons were characterized by the shortening renal tubules with impaired urine concentration. In addition, glomerular hypertrophy and occasional glomerulosclerosis developed with hypertension and albuminuria in adulthood. The present study can help to understand the risk of alternations of premature nephrons in preterm neonates.

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

BACKGROUND

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

AIMS

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

MATERIALS AND METHODS

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

RESULTS

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

DISCUSSION

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

CONCLUSIONS

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

Anesthesia for Maternal-Fetal Interventions: A Survey of Fetal Therapy Centers in the North American Fetal Therapy Network

INTRODUCTION

A wide range of fetal interventions are performed across fetal therapy centers (FTCs). We hypothesized that there is significant variability in anesthesia staffing and anesthetic techniques.

METHODS

We conducted an online survey of anesthesiology directors at every FTC within the North American Fetal Therapy Network (NAFTNet). The survey included details of fetal interventions performed in 2018, anesthesia staffing models, anesthetic techniques, fetal monitoring, and postoperative management.

RESULTS

There was a 92% response rate. Most FTCs are located within an adult hospital and employ a small team of anesthesiologists. There is heterogeneity when evaluating anesthesiology fellowship training and staffing, indicating there is a multidisciplinary specialty team-based approach even within anesthesiology. Minimally invasive fetal interventions were the most commonly performed. The majority of FTCs also performed ex utero intrapartum treatment (EXIT) and open mid-gestation procedures under general anesthesia (GA). Compared to FTCs only performing minimally invasive procedures, FTCs performing open fetal procedures were more likely to have a pediatric surgeon as director and performed more minimally invasive procedures.

CONCLUSIONS

There is considerable variability in anesthesia staffing, caseload, and anesthetic techniques among FTCs in NAFTNet. Most FTCs used maternal sedation for minimally invasive procedures and GA for EXIT and open fetal surgeries.

How should we assess renal function in neonates and infants?

AIM

Review of current knowledge on assessing renal function in term and preterm neonates.

METHODS

Literature review and analysis of own data.

RESULTS

Prematurity, genetic, environmental and maternal factors may alter peak nephron endowment and life-long renal function. Nephrogenesis continues until 34-36 weeks of gestation, but it is altered with premature delivery. Variability of nephron endowment has a substantial impact on the clearance of renally excreted drugs. Postnatally, glomerular function rate (GFR) increases daily, doubles by two weeks, and slowly reaches full maturity at 18 months of age. Ideally, renal function biomarkers should be expressed as age-independent z-scores, and evidence suggests indexing these values to post-conceptual age rather than chronological age. Newborn and maternal serum creatinine correlate tightly for more than 72 hours after delivery, rendering this biomarker unsuitable for the assessment of neonatal renal function. Cystatin C does not cross the placenta and may be the preferred biomarker in the neonate. Here, we provide preliminary data on the natural evolution of the cystatin C eGFR in infancy.

CONCLUSION

Cystatin C may be superior for GFR estimation in neonates, but the best approach to drug dosing of renally excreted drugs remains to be established.

Fetal surgery and neonatal ICU admissions

PURPOSE OF REVIEW

Fetal intervention is a dynamic field with wide-reaching implications on neonatal ICU admissions and the care of neonates with congenital anomalies. The aim of this review is to summarize recent advancements in fetal surgery and provide a broad understanding of how these topics interrelate.

RECENT FINDINGS

Advancements in prenatal imaging and diagnosis have dramatically expanded the indications for fetal intervention. Most recently, there has been a large focus on evaluating minimally invasive strategies of fetal intervention, notably fetoscopic surgery, and the use of stem cells for fetal treatment of myelomeningocele. With the advances in fetal intervention, neonatal care has adapted to the needs of these various patients to help improve the outcomes of this unique population.

SUMMARY

Fetal intevention relies on a multidisciplinary team from prenatal imaging and maternal fetal medicine to fetal surgery and postnatal subspecialty care, particuarly neonatology. Fetal intervention uniquely involves two patients, both mother and fetus, and therefore, has unique risks and considerations, particularly in the advancement of the field. As the number of conditions suited to fetal intervention grows, awareness and advancement of the postnatal intensive care necessary for these patients are essential.

Effectiveness of Prenatal Intervention on the Outcome of Diseases That Have a Postnatal Urological Impact

We reviewed the literature addressing outcomes of fetal intervention of conditions that require post-natal urological management including lower urinary tract obstruction, hydrometrocolpos, congenital adrenal hyperplasia, and myelomeningocele. Despite several decades of fetal intervention for these conditions, benefits remain elusive in part because of the enormous difficulty of conducting prospective randomized studies. In this review, we reached the following conclusions: Prenatal intervention in lower urinary tract obstruction (LUTO) improves survival in the worst cases by improving pulmonary function and it may be advantageous for renal function, particularly in patients with adverse urine parameters.Prenatal treatment of female fetuses at risk of having congenital adrenal hyperplasia (CAH) reduces virilization. Non-invasive fetal DNA analysis allows earlier diagnosis, reducing the risk of treating with dexamethasone males and non-affected fetuses.Fetal treatment of myelomeningocele (MMC) is gaining momentum. Prospective studies including standardized urologic evaluation will determine if the encouraging results reported by some hold on the long term follow-up.

Antenatal staging of congenital lower urinary tract obstruction

OBJECTIVE

To propose a staging system for congenital lower urinary tract obstruction (LUTO) capable of predicting the severity of the condition and its prognosis.

METHODS

This was a national retrospective study carried out at the eight Academic Hospitals in The Netherlands. We collected prenatal and postnatal data of fetuses at high risk of isolated LUTO that were managed conservatively. Postnatal renal function was assessed by the estimated glomerular filtration rate (eGFR), calculated using the Schwartz formula, considering the length of the infant and the creatinine nadir in the first year after birth. Receiver-operating characteristics (ROC) curve analysis, univariate analysis and multivariate logistic regression analysis with stepwise backward elimination were performed in order to identify the best antenatal predictors of perinatal mortality and postnatal renal function.

RESULTS

In total, 261 fetuses suspected of having LUTO and managed conservatively were included in the study. The pregnancy was terminated in 110 cases and perinatal death occurred in 35 cases. Gestational age at appearance of oligohydramnios showed excellent accuracy in predicting the risk of perinatal mortality with an area under the ROC curve of 0.95 (P < 0.001) and an optimal cut-off at 26 weeks' gestation. Fetuses with normal amniotic fluid (AF) volume at 26 weeks' gestation presented with low risk of poor outcome and were therefore defined as cases with mild LUTO. In fetuses referred before the 26^th week of gestation, the urinary bladder volume (BV) was the best unique predictor of perinatal mortality. ROC curve analysis identified a BV of 5.4 cm³ and appearance of oligohydramnios at 20 weeks as the best threshold for predicting an adverse outcome. LUTO cases with a BV ≥ 5.4 cm³ or abnormal AF volume before 20 weeks' gestation were defined as severe and those with BV < 5.4 cm³ and normal AF volume at the 20 weeks' scan were defined as moderate. Risk of perinatal mortality significantly increased according to the stage of severity, from mild to moderate to severe stage, from 9% to 26% to 55%, respectively. Similarly, risk of severely impaired renal function increased from 11% to 31% to 44%, for mild, moderate and severe LUTO, respectively.

CONCLUSIONS

Gestational age at appearance of oligo- or anhydramnios and BV at diagnosis can accurately predict mortality and morbidity in fetuses with LUTO. Our proposed staging system can triage reliably fetuses with LUTO and predict the severity of the condition and its prognosis. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Fetal Surgery

Fetal surgery is an established but still rapidly evolving specialty, born from the rationale that destructive embryologic processes, recognized early in gestation, can be curtailed by prenatal correction. As more and more centers begin offering fetal interventions, quality of care must be verified through transparency about clinical capabilities and resources. Level designations should be assigned based on capability, as in trauma and neonatal ICU centers for excellence, and volume requirements must be set for fetal surgery certification. Regionalization of this specialty care may be required to optimize outcomes.

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.

Prenatal renal parenchymal area as a predictor of early end-stage renal disease in children with vesicoamniotic shunting for lower urinary tract obstruction

BACKGROUND

Vesicoamniotic shunting (VAS) and other bladder drainage techniques for fetal lower urinary tract obstruction (LUTO) have been proven to ameliorate pulmonary hypoplasia and increase survival in patients with an initial poor prognosis. Currently there are limited prognostic tools available during gestation to evaluate and predict postnatal renal function.

OBJECTIVE

The aim was to describe the prenatal growth of the renal parenchymal area (RPA) in patients with LUTO and determine its application as a predictor of renal function at one year of life.

STUDY DESIGN

The study population comprised a retrospective cohort of all infants who survived the fetal VAS to birth. Renal growth and size were measured using imageJ software to calculate the RPA in sequential prenatal ultrasounds. The parenchymal area was measured from the image of each kidney with the greatest longitudinal length. These measurements were further correlated and analyzed as a predictor of end-stage renal disease (ESRD) within the first year of life.

RESULTS

Etiologies of LUTO in the 15 male fetuses included eight posterior urethral valves, four Eagle-Barrett/prune belly syndrome, two urethral atresia, and one megacystis microcolon intestinal hypoperistalsis syndrome. All patients had patent shunts, in place, at birth. Furthermore, ultrasonographic parameters such as oligohydramnios, keyhole sign, and bladder wall thickness showed no statistical difference between groups. Renal parenchymal growth correlated with postnatal renal function in both the ESRD (r = 0.409, p = 0.018) and the non-ESRD (r = 0.657, p < 0.001) groups. Most notably, RPA during the 3rd trimester predicted ESRD with the best cut-off point determined to be 8 cm² (sensitivity, 0.714; specificity, 0.882; and positive likelihood ratio, 6.071) (Table).

DISCUSSION

Despite definitive VAS for LUTO, postnatal morbidity and mortality remain high, emphasizing the role of renal dysplasia in postnatal renal failure, in spite of urinary diversion. Renal growth statistically differs between groups in the 3rd trimester of gestation; RPA development appears stagnant in patients that developed ESRD within the first year of life. In contrast, patients that did not develop ESRD continued to have renal parenchymal growth in a linear fashion. This suggests that prenatal RPA may be predictive of postnatal ESRD.

CONCLUSIONS

RPA measurement during the prenatal period could play an important role as a non-invasive tool to predict postnatal renal function and to anticipate postnatal clinical interventions.

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.

Lessons from the Barn to the Operating Suite: A Comprehensive Review of Animal Models for Fetal Surgery

The International Fetal Medicine and Surgery Society was created in 1982 and proposed guidelines for fetal interventions that required demonstrations of the safety and feasibility of intended interventions in animal models prior to application in humans. Because of their short gestation and low cost, small animal models are useful in early investigation of fetal strategies. However, owing to the anatomic and physiologic differences between small animals and humans, repeated studies in large animal models are usually needed to facilitate translation to humans. Ovine (sheep) models have been used the most extensively to study the pathophysiology of congenital abnormalities and to develop techniques for fetal interventions. However, nonhuman primates have uterine and placental structures that most closely resemble those of humans. Thus, the nonhuman primate is the ideal model to develop surgical and anesthetic techniques that minimize obstetrical complications.

Minimally Invasive Fetal Surgery

Fetal surgery corrects severe congenital anomalies in utero to prevent their severe consequences on fetal development. The significant risk of open fetal operations to the pregnant mother has driven innovation toward minimally invasive procedures that decrease the risks inherent to hysterotomy. In this article, we discuss the basic principles of minimally invasive fetal surgery, the general history of its development, specific conditions and procedures used to treat them, and the future of the field.

Sequential fetal serum β2-microglobulin to predict postnatal renal function in bilateral or low urinary tract obstruction

OBJECTIVE

Fetal serum β2-microglobulin has been shown to predict postnatal renal outcome in cases of fetal obstructive uropathy. We assessed the value of serial measurements of fetal serum β2-microglobulin in the prediction of postnatal renal outcome.

METHODS

We retrospectively studied renal outcome in 42 fetuses with bilateral or low urinary tract obstruction that had fetal blood sampling on at least two occasions to assay serum levels of β2-microglobulin. Amniotic fluid volume at the time of each sampling was recorded. We classified renal outcome as either favorable (when postnatal renal function was normal) or adverse (when postnatal chronic renal failure occurred or when renal dysplasia at autopsy was noted). A β2-microglobulin cut-off of 5 mg/L and amniotic fluid index of 5 cm were used to predict postnatal renal outcome.

RESULTS

Renal outcome was adverse in 28 cases and favorable in 14. In 12 (28.6%) cases, fetal serum β2-microglobulin concentration differed between the first and last measurement. Prediction of postnatal renal outcome was correct in 11 of these cases based on the last β2-microglobulin measurement. The sensitivity of β2-microglobulin in predicting renal outcome was significantly higher (P = 0.005) when using the last rather than the first measurement (96.4% vs 64.3%), with similar specificity for both measurements (85.7% vs 78.6%, non-significant). The sensitivity of amniotic fluid volume was also significantly higher (P = 0.005) when using the last rather than the first measurement (75.0% vs 35.7%), with similar specificity for both measurements (64.3% vs 71.4%, non-significant).

CONCLUSION

Sequential measurement of serum β2-microglobulin, performed for adverse ultrasound findings, such as renal parenchymal abnormality or decreasing amniotic fluid volume, predicts postnatal renal outcome more accurately than does a single assay. This may be due to possible worsening of renal injury with increasing duration of urinary tract obstruction. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Assessment of glomerular filtration rate in the neonate: is creatinine the best tool?

PURPOSE OF REVIEW

This article answers the question of whether creatinine is the best biomarker for monitoring neonatal glomerular filtration rate (GFR) in view of recent advances in measuring neonatal renal function.

RECENT FINDINGS

We rely largely on serum creatinine for the estimation of GFR in the newborn, even though creatinine is freely exchanged through the placenta. During the first few days of life, the serum creatinine reflects maternal renal function or the maternal creatinine. Back filtration of creatinine in preterm newborns is also a serious limitation. This review summarizes current knowledge on the prenatal and postnatal handling of creatinine as well as that of other, more novel biomarkers of GFR, such as cystatin C (CysC) and β-trace protein (BTP). Only small amounts of CysC cross the placenta, whereas BTP does not cross the placenta at all. However, BTP measurements are not widely available. Recent studies on renal volumetry are also discussed.

SUMMARY

Currently, CysC may be the most suitable marker of neonatal renal function, but its availability is still limited, it is more costly, and the best method of reporting acute kidney injury and neonatal estimated GFR remains to be established.

Is late-preterm birth a risk factor for hypertension in childhood?

Late-preterm birth is associated with higher rates of neonatal morbidity and mortality and higher health care utilization, but its impact on later life is not well known. In this study, we aimed to evaluate whether late-preterm birth affects blood pressure, renal function, and urinary protein excretion in children later in life. Sixty-five children aged 4 to 13 years born as late-preterm and 65 age- and sex-matched children born full term were evaluated with 24-h ambulatory blood pressure monitoring (ABPM), urinary microalbumin excretion (UAE), and glomerular filtration rate (GFR). All subjects underwent ABPM prospectively. For each gender, daytime, nighttime, and 24-h systolic and diastolic and mean blood pressures (SBP, DBP, and MAP) were transformed to standard deviation scores (SDS). Blood pressure profiles (SBP DBP, and MAP) were considered abnormal when the corresponding SDS values exceeded 1.63. Urinary microalbumin excretion was expressed as milligrams per day, and the value between 30 and 300 mg/day was defined as microalbuminuria (MA). There was no significant difference in the mean GFR and MA levels between late-preterm and term children. 24-h systolic BP SDS, daytime systolic BP SDS, nighttime systolic BP SDS, 24-h diastolic BP SDS, nighttime diastolic BP SDS, 24-h MAP BP SDS, daytime MAP BP SDS, and nighttime MAP BP SDS were found to be significantly higher in late-preterm children compared to term children.

CONCLUSION

We conclude that late-preterm children have higher BP levels, so those children should be followed up carefully by the pediatrician regarding probable hypertension in their future life.

Antenatally diagnosed hydronephrosis: current postnatal management

The issue of antenatal hydronephrosis has become a routine component for the care of a pregnant woman despite limited evidence of a clinical benefit. The genitourinary tract represents the most commonly detected organ system with identified abnormalities, with antenatal hydronephrosis (ANH), being the most notable and common finding. ANH represents a spectrum, with most cases being a trivial and inconsequential finding on maternal fetal ultrasound. However, there is a correlation with increased grades of ANH being associated with increased severity of urinary tract pathology. Most patients can be managed expectantly with appropriate evaluation commenced postnatally based on severity of ANH and proper parental counseling and education. The purpose of this review was to assess current literature and guidelines pertaining to ANH and incorporate our practical interpretations of their significance.

Developmental changes in renal function

PURPOSE OF REVIEW

Although nephrogenesis in a term infant is complete, there are a number of functional changes that occur in the kidney as the infant matures. Understanding these changes will aid in the evaluation of neonates to delineate what is normal development versus a pathophysiologic problem. In addition, as many drugs are either cleared by the kidneys or can affect renal function, dosing regimens are dramatically different in the neonate as compared with the adult. These differences are greatly exaggerated in the preterm infant, making it more difficult to determine if there is a pathophysiologic problem.

RECENT FINDINGS

While investigators in recent years have made great strides in understanding the early embryology of the kidney and the molecular signals involved in the formation of the kidney, there remains a paucity of functional studies. The most recent studies have re-examined the changes in the serum creatinine in the newborn and how this impacts the excretion of drugs. Developmental changes in the renal tubule transport systems and their regulation have also been more extensively studied.

SUMMARY

The kidney undergoes many developmental physiologic changes as the neonate adapts to extra-uterine life. Understanding these changes will help in the medical management of these infants.

Fetal surgery for severe lower urinary tract obstruction

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

The maternal side of maternal-fetal surgery

The term fetal surgery is used widely for fetal intervention during pregnancy; maternal-fetal surgery may be more appropriate, because all these invasive procedures also affect the mother. Although there is no direct benefit to the mother from these procedures, the risk to her is for a purely altruistic purpose. It is therefore important to understand the potential complications of maternal-fetal surgery, so the physician can provide accurate counseling to the patient.

Invasive prenatal diagnostic techniques

Subspecialization in fetal medicine has expanded the scope for obstetricians to investigate the fetus and its surrounding environment in greater detail. Of the advances in technology that have made this possible, ultrasonography is the most important. A high degree of skill is required if it is to be applied to the performance of invasive diagnostic techniques. These should be performed only in specialized centres with appropriate facilities and an adequate referral base. However, it is important for obstetricians to know what is possible in the field of prenatal diagnosis and therapy in order to give patients the best advice.

Renal scintigraphy in infants with antenatally diagnosed renal pelvis dilatation

BACKGROUND/AIM

Ureteropelvic junction obstruction and vesicoureteral reflux are the most frequent entities identified on the basis of antenatal hydronephrosis. The aim of this study was to determine the incidence and pattern of abnormal renal scintigraphy findings in postnatal investigation of children with antenatal hydronephrosis.

METHODS

Twenty-four infants (19 boys and five girls) presented with antenatal hydronephrosis and mild to moderate hydronephrosis on ultrasound in newborn period were referred for renal scintigraphy. Ten patients with vesicoureteral reflux documented on micturating cystoureterography underwent 99mTc-DMSA renal scintigraphy and 14 patients were subjected to 99mTc-DTPA scintigraphy.

RESULTS

Anteroposterior pelvic diameter on ultrasound ranged from 11 to 24 mm. Renal DMSA scans identified congenital scars in two boys with bilateral reflux of grade V and unilateral reflux of grade III. Relative kidney uptake (RKU) less than 40% was found in three, and poor kidney function (RKU less than 10%) in two patients. Significant obstruction was shown on DTPA diuretic renal scintigraphy in 6/14 patients. Some slowing in dranaige (T1/2 greater than 10 minutes) with no reduction in differential renal function was identified in three patients. Differential renal function less than 10% was obtained in one case.

CONCLUSION

A high percent of abnormal renal scintigraphy findings was obtained. Renal scintigraphy was useful in determination of underlying cause of antenatally detected hydronephrosis.

Prognosis of antenatally diagnosed oligohydramnios of renal origin

Although clinical outcome data on fetuses with oligohydramnios of renal origin are scarce, prognosis is regarded as poor due to a high risk of renal dysfunction and pulmonary hypoplasia. This review aims to summarize the current knowledge and clinical experience with patients presenting antenatally with renal oligohydramnios. By reviewing the underlying mechanisms, complications, and outcome data, we hope to further improve antenatal counseling and postnatal care. We conclude that prognosis of ROH has changed in recent years. While early data before the introduction of sophisticated neonatal intensive care and renal replacement therapy indicated a poor prognosis, nowadays, a much more optimistic prognosis of children after renal oligohydramnios can be expected from the recent publications in the literature.

Recent developments in fetal medicine

Several advances have been made in the field of fetal medicine since the last BMJ review on the subject. This review covers advances in prenatal screening, imaging techniques, management of multiple pregnancies, and fetal therapy

Distal urinary obstruction

Despite the sound experimental basis and initial promise of early animal models, the results of antenatal intervention have been disappointing, with high rates of misdiagnosis of urethral valves, complications from vesicoamniotic shunting, perinatal mortality, and long-term renal impairment and bladder dysfunction in survivors. The recent development of a cystoscopic approach might obviate some of these problems, but to date the procedure been limited by technical difficulty in negotiating the urethrovesical angle. Overcoming these difficulties through equipment modifications might allow definitive testing of whether or not alleviating distal urinary obstruction in utero is beneficial.

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.

Consensus on the prenatal management of antenatally detected urological abnormalities

PURPOSE

The incidence of an antenatally detected genitourinary abnormality is 0.5% of all pregnancies assessed, and rarely is antenatal intervention indicated. A survey of pediatric urologists was undertaken to evaluate current practice patterns and recommendations regarding the need to intervene in the antenatal period.

MATERIALS AND METHODS

A survey instrument was mailed to all members of the Society for Fetal Urology. There were 7 case scenarios that addressed critical decision points in patients with antenatally detected genitourinary abnormalities.

RESULTS

A total of 112 of 188 Society for Fetal Urology members (60%) completed the survey. Observation with serial ultrasound was recommended for a 32-week fetus with ureteropelvic junction obstruction. For a 36-week fetus with suspected posterior urethral valves without oligohydramnios most respondents elected no intervention with a minority favoring early delivery. For a 23-week fetus with suspected posterior urethral valves and oligohydramnios with normal bladder electrolytes most respondents agreed with a vesicoamniotic shunt. There was no clear consensus for a 20-week fetus with suspected posterior urethral valves, oligohydramnios and a nonfunctioning right kidney. Most respondents recommended serial ultrasound to follow an 18-week fetus with suspected posterior urethral valves and normal amniotic fluid. Antenatal intervention was not recommended for a 20-week fetus with bilateral renal cystic disease, and most respondents elected no intervention for a 28-week fetus with a solitary kidney with suspected ureteropelvic junction obstruction and normal amniotic fluid.

CONCLUSIONS

Situations that warrant antenatal intervention for a genitourinary abnormality are exceedingly low and may include cases of oligohydramnios, suspected favorable renal function and the absence of life threatening congenital abnormalities. In cases with normal amniotic fluid antenatal intervention is not recommended regardless of the detected abnormality. There is an emerging trend toward early delivery of fetuses with severe genitourinary abnormalities, normal amniotic fluid and confirmed lung maturity.

Consensus on the prenatal management of antenatally detected urological abnormalities

PURPOSE

The incidence of an antenatally detected genitourinary abnormality is 0.5% of all pregnancies assessed, and rarely is antenatal intervention indicated. A survey of pediatric urologists was undertaken to evaluate current practice patterns and recommendations regarding the need to intervene in the antenatal period.

MATERIALS AND METHODS

A survey instrument was mailed to all members of the Society for Fetal Urology. There were 7 case scenarios that addressed critical decision points in patients with antenatally detected genitourinary abnormalities.

RESULTS

A total of 112 of 188 Society for Fetal Urology members (60%) completed the survey. Observation with serial ultrasound was recommended for a 32-week fetus with ureteropelvic junction obstruction. For a 36-week fetus with suspected posterior urethral valves without oligohydramnios most respondents elected no intervention with a minority favoring early delivery. For a 23-week fetus with suspected posterior urethral valves and oligohydramnios with normal bladder electrolytes most respondents agreed with a vesicoamniotic shunt. There was no clear consensus for a 20-week fetus with suspected posterior urethral valves, oligohydramnios and a nonfunctioning right kidney. Most respondents recommended serial ultrasound to follow an 18-week fetus with suspected posterior urethral valves and normal amniotic fluid. Antenatal intervention was not recommended for a 20-week fetus with bilateral renal cystic disease, and most respondents elected no intervention for a 28-week fetus with a solitary kidney with suspected ureteropelvic junction obstruction and normal amniotic fluid.

CONCLUSIONS

Situations that warrant antenatal intervention for a genitourinary abnormality are exceedingly low and may include cases of oligohydramnios, suspected favorable renal function and the absence of life threatening congenital abnormalities. In cases with normal amniotic fluid antenatal intervention is not recommended regardless of the detected abnormality. There is an emerging trend toward early delivery of fetuses with severe genitourinary abnormalities, normal amniotic fluid and confirmed lung maturity.

Fetal obstructive uropathy: patterns of renal pathology

Fetal obstructive uropathy (FOU) is characterized by obstruction of the urethra, renal anomalies, ureterovesical dilatation, oligohydramnios, cryptorchidism, and abdominal muscle wall changes. The main objective of the present study was to better understand the relationship between FOU and renal pathology using a series of 15 male autopsy cases. A total of 11 cases with patent anus and 4 with imperforate anus were analyzed. Of the first group, most cases showed obstruction at the level of prostatic urethra. Seven cases showed obstruction at the level of the prostatic urethra and histologic study revealed scarring and partial or complete absence of the prostate, while in the remaining four cases the prostate was present. Of the cases with imperforate anus, two showed obstruction at the level of prostatic urethra, one showed posterior urethral valves, and one was obstructed at the proximal urethra. In all cases the kidneys showed mixed (dysplastic and cystic) changes with no significant differences between the two groups. An inverse correlation was observed between degree of renal dysplasia and gestational age, whereas the opposite was true for cystic changes. Distal and collecting tubules were more intensely immunoreactive to the anti-cytokeratin antibody when compared to proximal tubules. Moreover, anti-cytokeratin immunoreactivity was more prominent in tubules displaying cystic dilatation. DNA fragmentation analysis of renal tissue revealed a higher apoptosis of mesenchymal and tubular cells in the FOU cases, compared to gestational aged-matched controls. These results suggest that renal anomalies in FOU might be related to the gestational age at which the injury occurred and to the duration of the obstruction.

The pathogenesis of dysplastic kidney in a urinary tract obstruction in the female fetal lamb

BACKGROUND/PURPOSE

The type of renal dysplasia resulting from obstructive uropathy depends on the completeness of the obstruction and its timing with respect to the stage of glomerulogenesis at the time of the obstruction. The authors created a successful obstructive uropathy model in the female fetal lamb to demonstrate the differing pathogenesis of renal dysplasia.

METHODS

Female fetal lambs at 60 and 90 days' gestation had their urethra and urachus ligated transabdominally and were delivered by cesarean section at 145 days (full term). Kidney length and cortical thickness were measured, and samples were examined histologically. In the lambs operated on at 90 days, the urine was collected at delivery and Na and CI were measured and compared with the results obtained from normal full-term lambs.

RESULTS

Seven of 10 female lambs had hydronephrosis or dysplastic kidneys. The cortext to kidney length ratio was 10+/-3% in the 90-days hydronephrotic group versus 29+/-6% in the controls (P<.001). Morphologically, the 90-day model had dilatation of the collecting tubules with normal glomerular numbers. The 60-day model had tubular cysts with fibromuscular cuffing and reduced glomerular numbers. The fetal urine Na was 47+/-3.3 mmol/L in controls versus 78+/-24 mmol/L in the hydropnephrotic lambs (P<.05). The urine CI in these lambs was 38+/-8.6 mmol/L in controls versus 55+/-14.5 mmol/L in the hydronephrotic lambs (P<.05).

CONCLUSIONS

An obstructive uropathy model was created in female fetal lambs. There were no dysplastic changes in the kidneys in lambs operated on at 90 days' gestation, but there were definite dysplastic changes in those operated on at 60 days. Concentrations of Na and CI in the fetal urine are higher than normal in the 90-day model.

Prospective study of outcome in antenatally diagnosed renal pelvis dilatation

AIMS

To ascertain the outcome associated with antenatal renal pelvis dilatation; to recommend guidelines for postnatal investigation and determine an upper limit of normal for the anterioposterior dimensions of the fetal renal pelvis.

METHODS

Infants whose antenatal ultrasound scan showed a fetal renal pelvis of 5 mm or greater were investigated using postnatal renal tract ultrasound and a micturating cystogram. Isotope studies were also performed, where appropriate.

RESULTS

Vesicoureteric reflux (VUR), the most common diagnosis, was evident in 23/104 (22%). In 14 infants with VUR the postnatal ultrasound scan was normal. There was no evidence of renal scarring or dysplasia in any of the refluxing kidneys. Other diagnoses were pelviureteric junction obstruction, renal dysplasia, and idiopathic dilatation. Antenatal counselling and parental information facilitated postnatal assessment.

CONCLUSIONS

Infants with antenatal renal pelvis measurements of 5 mm or greater should be investigated postnatally, as a significant percentage will have VUR. A normal postnatal ultrasound scan does not preclude the presence of VUR.

The current approach to the assessment of fetal renal function: fact or fiction?

The wide use of ultrasonography during pregnancy has led to the identification of a relatively large number of renal and urinary tract abnormalities, particularly hydronephrosis. Uncertainty, however, exists regarding the indications for surgical intervention. Prominent among the variables currently used to assess fetal renal function and predict the long-term outcome are measurements of urinary concentration of electrolytes and low molecular weight proteins. It has become, therefore, imperative to examine the evidence on which the selection of these variables is based, before they become entrenched in medical practice. The analysis reveals that single measurements of any of these variables is unlikely to be reliable. Sequential measurements, albeit more dependable, are impractical due to the narrow window of opportunity for useful surgical intervention. It is therefore necessary to search for new, innovative approaches aimed at detecting changes in the kidney or urine that reflect the biological response of the developing kidney to injury. Such markers may be represented by renal metabolites or peptides involved in the maintenance of renal function under conditions of stress.

The radionuclide assessment of pre-natally diagnosed hydronephrosis

OBJECTIVE

To determine if a pre-operative non-invasive radionuclide study can predict the results of surgery in infants with pre-natally diagnosed hydronephrosis.

PATIENTS AND METHODS

Eight male infants with prenatally diagnosed hydronephrosis were treated by pyeloplasty within the first 4 months of life. All infants underwent a pre-operative diuresis renogram and a dimercapto-succinic acid (DMSA) scan, followed by a further renogram 6 months after surgery to assess renal function and drainage.

RESULTS

There was a significant difference between the results of the relative renal function estimates obtained by the pre-operative renogram and the pre-operative DMSA scan (P = 0.001). In all patients the recovery in renal function following surgery was accurately predicted by the pre-operative DMSA scan.

CONCLUSION

The results of this preliminary study suggest that a pre-operative DMSA scan could replace the use of invasive nephrostomy drainage to assess the potential for recovery in the poorly functioning neonatal kidney and give an indication of those kidneys most likely to benefit from reconstructive surgery.

The fetus as a patient. Surgical considerations

The diagnosis and treatment of human fetal defects has evolved rapidly over the past decade due to improved fetal imaging techniques and better understanding of fetal pathophysiology derived from animal models. The detection of a fetal anomaly may now lead to a change in the timing of delivery, a change in the mode of delivery, or prenatal treatment. Because most therapeutic maneuvers involve some risk to the fetus and mother, there must be a reasonable expectation that the procedure is feasible, safe, and effective before it can be attempted in humans. This requires reliable information about the pathophysiology and natural history of the disease process, the efficacy of fetal surgical intervention in ameliorating the disease, and the feasibility and safety of the proposed intervention. This paper focuses on the rationale and initial clinical experience with fetal surgery for a variety of life-threatening fetal anatomic defects.

[Fetal curarization by umbilical cord puncture during pregnancy]

Two cases of foetal neuromuscular blockade carried out to obtain foetal immobility during long procedures (in utero foetal exchange transfusion, foetal imaging) are reported. The blockade was carried out in the operating theatre, the mother being awake. Foetal weight had been estimated according to usual echographic parameters. After a long needle had been inserted in the umbilical vein under the guidance of ultrasonography, 0.1 mg.kg-1 vecuronium was injected. Muscle paralysis lasted for about 2 hours in both cases, foetal movements returning spontaneously. There were no side effects due to this technique, a transient foetal bradycardia excepted. Foetal neuromuscular blockade by direct cord injection of muscle relaxants seems to be a simpler, and perhaps safer, technique than obtaining foetal immobility by maternal anaesthesia.

Fetal intervention in obstructive uropathy: prognostic indicators and efficacy of intervention

Management of the fetus with bilateral hydronephrosis is controversial; ability to predict outcome and efficacy of prenatal intervention are unknown. We studied 40 fetuses referred for ultrasonography, examination of fetal urine, and possible therapy. We retrospectively assigned fetuses to a good prognosis group if fetal urine was hypotonic (sodium less than 100 mEq/L, chloride less than 90 mEq/L, osmolarity less than 210 mOsm/L) and there was no ultrasonographic evidence of dysplasia; we assigned fetuses to a poor prognosis group if even one criterion was abnormal. Survival was greater in the good prognosis group than in the poor prognosis group (81% vs 12.5%; 87% vs 30%, excluding abortions) (p less than 0.005). We then attempted to assess the efficacy of prenatal urinary decompression by comparing outcome within the good and poor prognosis groups. Survival with intervention was greater in both the good prognosis group and the poor prognosis group (89% vs 70% and 30% vs 0%). In 6 of the 8 survivors in the good prognosis group, severe oligohydramnios was reversed by decompression. We conclude the fetal urine electrolyte levels and ultrasonographic appear helpful in predicting residual fetal renal function and neonatal outcome and that prenatal decompression may prevent the development of fatal pulmonary hypoplasia.

Maps for diagnosis and management of antenatal urinary tract dilatation

Despite advances in radiological imaging techniques, the ideal management of antenatally diagnosed hydronephrosis remains controversial. A map, showing diagnostic and management pathways, has been designed in an attempt to provide maximum information from the most appropriate and minimum number of investigations.

Value of antenatal diagnosis of abnormalities of the urinary tract

OBJECTIVE

To assess the value of antenatal diagnosis of abnormalities of the urinary tract on ultrasonography.

DESIGN

Retrospective study.

SETTING

Two obstetric units in Glasgow.

SUBJECTS

62 Fetuses in which renal abnormalities were diagnosed on antenatal ultrasonography.

INTERVENTIONS

Six fetuses had their bladders aspirated to determine renal function. Fifteen pregnancies were terminated on the basis of the findings on antenatal ultrasonography, and if possible necropsy was performed on the fetuses. In babies who were born alive the final diagnosis was made by postnatal ultrasonography, intravenous urography, radionuclide scanning, cystography, and, in those who died in the early neonatal period, necropsy. Neonates who were referred with a known obstructed kidney had nephrostomy or pyeloplasty.

END POINT

Assessment of the value of antenatal diagnosis of renal abnormalities on ultrasonography for babies who had no clinical evidence of disease postnatally.

MAIN RESULTS

Eighteen fetuses did not survive birth; the antenatal diagnosis was accurate in all 18. Of the 44 babies born alive, five had normal urinary tracts, in two of whom antenatal ultrasonography had probably indicated a false positive diagnosis. Fourteen babies died during the early neonatal period. Twenty five babies with renal abnormalities were followed up; the antenatal diagnosis was inaccurate for 10 of them, the commonest misdiagnosis being hydronephrosis for multicystic kidney and vice versa, and there was one false positive diagnosis. The initial clinical findings in 14 babies would have led to the early detection of a urological abnormality. In the 30 babies with no clinical evidence of disease the antenatal diagnosis was of definite value in eight, probable value in 15, and marginal value in seven. Overall, an accurate antenatal diagnosis was made in 46 of the 62 cases (74%); in 12 cases renal disease was detected but its specific nature was not determined; and in four cases the diagnosis was misleading.

CONCLUSIONS

The overall value of antenatal diagnosis is that it indicates early termination of fetuses with fatal renal disease, prepares parents and medical staff for the likelihood of serious neonatal problems, and shows abnormalities of the urinary tract that may not be detected postnatally.

Early experience with open fetal surgery for congenital hydronephrosis

The fetus with severe bilateral hydronephrosis and associated oligohydramnios in the second trimester is doomed at birth by ongoing pulmonary and renal damage. Since decompression with percutaneously placed catheters anesthetic, surgical, and tocolytic techniques for open fetal anesthetic, surgical, and tocolytic techniques for open fetal urinary tract decompression in animals, and have now applied those techniques to a small group of five patients. One had bilateral ureterostomies and the subsequent four had marsupialization of the bladder. All pregnancies proceeded to cesarean delivery at 32 to 35 weeks' gestation. There was no long-term maternal morbidity, and two mothers have since experienced normal pregnancies. Three fetuses had return of normal amniotic fluid dynamics, and all three had adequate pulmonary function at birth, suggesting that fatal pulmonary hypoplasia associated with early severe oligohydramnios had been reversed. Two neonates died at birth with pulmonary hypoplasia. One had no amniotic fluid even after decompression, and the other had some amniotic fluid after decompression but a tiny chest cavity due to the long period of severe oligohydramnios before decompression. Of the three surviving infants, one had normal renal function when she died of unrelated causes at 9 months of age. One has normal renal function at 23 months and the third had failing renal function at 2 1/2 years and has grown and developed normally, but will require renal transplantation. We have now developed selection criteria that would exclude from treatment the two fetuses who died of pulmonary hypoplasia and the one who developed renal failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical outcome of fetal uropathy

Thirty seven infants (27 boys and 10 girls) whose uropathy had been diagnosed antenatally were reviewed at a mean age of 24.4 months. Antenatal ultrasonography was found to be an accurate detector of renal disease, as uropathy was subsequently confirmed in 33 of the 37 infants (89%). A smaller proportion of patients required operations than in other series reported. Shortly after birth the kidney undergoes physiological adjustments and investigation may be carried out too soon. It should be delayed, especially if the infant is well. The timing of postnatal ultrasonography is important and the advice of a paediatric urologist should be sought before investigations are carried out.

Prenatal diagnosis of urinary tract malformation

Malformation of the urinary tract (UT) is among the most common of all congenital malformations. Prior to the common usage of prenatal ultrasound, these anomalies were undetected until pediatric complications prompted investigation. When diagnosed and treated in early infancy, children with urinary tract malformations have a much better prognosis than when diagnosis is delayed beyond 1-2 years. Since the first report of the prenatal diagnosis of polycystic kidney disease by Garrett et al. in 1970, most forms of congenital urinary tract malformation have been diagnosed antenatally with the use of sonography. A review of the normal and abnormal development of the urinary system, some genetic aspects of UT malformations, and an overview of the major UT anomalies and their prenatal diagnosis is presented.

Prenatal diagnosis and management of bilateral hydronephrosis

This report reviews the management of the fetus with congenital hydronephrosis (CH), a challenging diagnostic and therapeutic problem. Experimental models of obstructive uropathy have produced histologic changes similar to those seen in kidneys of human neonates with congenital hydronephrosis. Relief of obstruction in utero in these models has been shown to prevent some of the dysplastic changes caused by obstruction. These studies have formed the theoretical basis for in utero decompression to restore amniotic fluid dynamics to prevent death from pulmonary hypoplasia, and reverse or arrest dysplastic morphogenesis. The development of prognostic criteria has greatly aided in selection of appropriate fetuses for intervention. These criteria include: (1) Na less than 100 mEq/l; (2) Cl less than 90 mEq/l; (3) osmolarity less than 210 mosmol; (4) sonographic appearance of the fetal kidneys; (5) amniotic fluid status; (6) urine output at fetal bladder catheterization. All fetuses should have ultrasonography to exclude other anomalies, and karyotype analysis to exclude chromosomal abnormality. If amniotic fluid volume is normal, the pregnancy is followed with serial ultrasound examinations. If oligohydramnios develops, a prognostic evaluation is performed, including fetal bladder catheterization. If the fetus has poor residual renal function, on the basis of prognostic criteria, appropriate counseling may be given. If the fetus has good residual renal function, depending on lung maturity, it can be delivered early for corrective surgery. If diagnosed prior to lung maturity in utero, decompression by either vesicoamniotic shunting or open fetal surgery may be attempted in the highly selected case.(ABSTRACT TRUNCATED AT 250 WORDS)