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

Ultrasound-guided procedures for prenatal diagnosis and therapy

Ultrasonography has expanded the capabilities of perinatologists to examine,test, and treat the fetus. Amniocentesis and CVS are safe and widely available procedures, which can be used to diagnose a multitude of abnormalities through karyotype analysis and molecular studies. CVS allows earlier diagnosis, but both procedures can provide highly accurate results in the first half of pregnancy. Cordocentesis has fewer indications, but allows direct laboratory testing of fetal blood. Fetocentesis and fetal biopsy are reserved for limited indications, but can play a crucial role in the diagnosis of some conditions, which cannot be assessed less invasively. Fetal transfusion is an important tool in the treatment of isoimmunization, some other forms of fetal anemia, and alloimmune thrombocytopenia. Amnioreduction is a commonly used procedure for the treatment of polyhydramnios and TTTS. Multifetal reduction and selective termination offer previously unavailable options to patients carrying multiple gestations. Fetal shunts can reduce perinatal morbidity and mortality in cases of bladder outlet obstruction and hydrothorax. The limited experience with cord ligation procedures and balloon valvuloplasty suggests these relatively new procedures may serve a greater role in the future as techniques are improved. By providing guidance for all of these procedures, real-time ultrasonography has revolutionized prenatal diagnosis and therapy; it will continue to be a crucial component in evaluating and treating complicated pregnancies.

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.

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.

Prenatal ultrasound guided percutaneous shunts for obstructive uropathy and thoracic disease

The authors reviewed the status of closed ultrasound-guided fetal therapy using a pigtail shunt to create vesicoamniotic or thoracoamniotic decompression of the fluid-filled space. This review includes published and textbook reports of in utero therapy for bladder obstruction, pleural effusion, and macrocystic adenomatoid malformation from 1985 through 2002. For fetuses affected by lower urinary tract obstruction, the key component is identifying those fetuses that have retained renal function and are most likely to benefit from in utero shunting. This good prognosis group has been shown to have improved survival rate and a lower incidence of renal failure. Complications of fetal loss are estimated at 5% owing to the shunt procedure, and the risk of shunt displacement varies from 30% to 50%. Hydrops secondary to primary PE has been shown to be associated with low fetal and neonatal survival at 21% to 23%. Treatment by thoracoamniotic shunting increases survival rate to 75%. The fetus with a macrocystic CCAM and secondary hydrops should be considered a candidate for thoracoamniotic shunt to decrease CCAM volume, reverse hydrops, and improve survival rate. Thoracoamniotic shunt and thoracocentesis pregnancy loss risks for pleural effusion (PE) and macrocystic adenomatoid malformation of the lung (CCAM) are 5% and 0.5% to 1.0%, respectively.

Enlarged fetal bladder: Differential diagnosis and outcomes

The sonographic finding of an enlarged fetal bladder may simply be a transitory normal variant, but it may also be secondary to reflux or to obstructive, neurogenic, or myopathic causes. In this report, we describe the cases of 3 fetuses with an enlarged bladder, each of which had a different cause. The first fetus had posterior urethral valve obstruction, the second, a ruptured neurogenic bladder, and the third, megacystic-microcolon-intestinal hypoperistalsis syndrome. When sonographic examination reveals an enlarged fetal bladder, the ureter, kidneys, genitalia, and spine should be evaluated carefully. Although sonography is good at identifying urinary tract abnormalities, it often cannot provide the specific diagnosis or cause. We recommend frequent sonographic monitoring to evaluate such fetuses for persistence of or changes in bladder enlargement and for changes in the volume of amniotic fluid because these signs may be indicators of abnormalities of renal function and risk factors for a poor prognosis. Analysis of fetal electrolyte levels can also aid in determining the prognosis and whether the condition is amenable to therapeutic intervention.

Prenatal intervention: ethical considerations for life-threatening and non-life-threatening anomalies

Ethical issues in maternal-fetal surgery require special consideration because of the often-conflicting interests of the mother and fetus. Over the past 2 decades an ethical framework for fetal therapy and maternal-fetal surgery has been developed. This framework continues to evolve as new procedures are developed and new controversies arise. The most recent ethical challenge has been the application of maternal-fetal surgery to nonlethal fetal anomalies, specifically, repair of fetal myelomeningocele. Such procedures require early evaluation by randomized clinical trials to avoid premature dissemination of unproven therapy. These trials currently are being initiated, and the ethical framework for proceeding requires careful consideration. This review will summarize the current ethical issues and controversies in maternal-fetal surgery in the context of these new developments.

Different phenotypes of dysplastic kidney in obstructive uropathy in fetal lambs

PURPOSE

The cause of cyst production in renal dysplasia is uncertain. The authors hypothesized that different patterns of renal dysplasia result from variations in the timing and site of the urinary tract obstruction.

METHODS

The authors operated on fetal lambs at 50 and 60 days' gestation. Male lambs underwent urethral and urachal ligation and female lambs unilateral ureteric ligation. They were delivered by cesarean section at 145 days' gestation and killed.

RESULTS

Of 12 lambs operated on at 50 days' gestation, 4 survived. Of 26 lambs operated on at 60 days, 21 survived. The authors identified 3 types of dysplastic kidneys. Type A, fibrotic kidneys (2.2 g) with no cysts and interstitial fibrosis. There were reduced numbers of proximal tubules, but distal tubules and collecting ducts persisted. (50-day obstruction, n = 5 kidneys); type B, Sponge-like kidneys (37g): these had large cysts with minimal interstitial fibrosis. (87% of 60-day uretheral and urachal ligation model n = 12 kidneys); Type C, Small kidneys (4.8 g) with no large cysts (60-day Ureteric ligation model n = 7 kidneys).

CONCLUSION

The authors produced 3 different types of renal dysplasia by creating urinary tract obstruction at different sites and gestational ages.

In utero therapy for lower urinary tract obstruction

Lower urinary tract obstruction has a significant impact on neonatal and child health. Pulmonary hyperplasia and renal impairment could be direct or indirect consequences of this condition leading to significant morbidity and mortality. Evaluation of fetuses with suspected lower urinary tract obstruction is performed not only to confirm the diagnosis but also to assess renal prognosis. Ultrasound examination and urinary analysis aid in the evaluation of these fetuses. The decision to perform fetal intervention in these cases is a difficult one. Vesico-amniotic fetal shunting, open fetal surgery and more recently endoscopic fetal surgery for this condition are available as possible modalities of fetal intervention. Case selection for fetal intervention is extremely important in order to both avoid unnecessary intervention in those unlikely to survive, and also to avoid procedure related complications in fetuses likely to do well without intervention. Vesico-amniotic shunting has the advantage of bypassing the obstruction, however it is often associated with complications. Open fetal surgery is not usually recommended because of the complications and high fetal loss rate. Endoscopic surgery to visualise and treat the cause of lower urinary tract obstruction has been tried. Fetal endoscopic surgery is in its infancy and endoscopic procedures are limited to a few groups. This current review addresses evaluation, case selection and therapeutic options for lower urinary tract obstruction in utero. It also discusses the limited data against which the efficacy of the various options can be assessed. The current state of fetal intervention is detailed in the present review.

Invasive assessment of fetal renal abnormalities: urinalysis, fetal blood sampling and biopsy

There are a number of potential biochemical markers that may have some role in predicting renal function postnatally. These include urinary sodium, calcium and beta2-microglobulin. The latter may also be measured in fetal serum. However, the accuracy of these parameters at a point in time is far from perfect as urinary tract obstruction is a progressive disease which may be best defined by repeated observations throughout pregnancy.

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

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

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.

Prenatal diagnosis and management of abnormalities in the urologic system

We have reviewed the prenatal diagnosis and management of abnormalities in the urologic system. Urologic anomalies may be caused by embryologic aberrations, genetic disease, or a nonrandom association with other structural abnormalities. There is a wide range of prognoses, depending on the cause and the impact of the anomaly on the production of amniotic fluid. Management focuses on obtaining an accurate prenatal diagnosis, providing appropriate counseling, and ensuring the proper surveillance or treatment before and after birth.

Prune-belly syndrome: therapeutic options including in utero placement of a vesicoamniotic shunt

The prune-belly syndrome (PBS) consists of abdominal wall distention with deficiency of the abdominal wall musculature, urinary tract abnormalities, and cryptorchidism. The impaired drainage of the bladder leads to oligohydramnios and pulmonary hypoplasia. We present 4 cases of PBS diagnosed by prenatal sonography. In 2 cases, vesicoamniotic shunt therapy was not indicated because of a poor prognosis based on sonographic and laboratory findings; the pregnancies were terminated. In another case, treatment was not performed because of a twin pregnancy, and the neonate with PBS died the day of delivery by cesarean section at 31 weeks' menstrual age. In the other case, vesicoamniotic shunt therapy was successfully performed, and a healthy child was delivered. Several conditions must be met for vesicoamniotic shunt therapy to have a good chance of success: the karyotype must be normal, other malformations must be excluded by careful sonographic examination, and renal function must be normal, as determined by serial analyses of fetal urine. Generally, the shunt should be inserted as early as possible.

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 hydrolaparoscopy and endoscopic cystotomy in complicated cases of lower urinary tract obstruction

OBJECTIVE

Vesicoamniotic shunting may be difficult or impossible in selected cases of fetal lower obstructive uropathy. The purpose of this article is to describe the performance of fetal hydrolaparoscopy and endoscopic fetal cystotomy in two fetuses with complicated lower obstructive uropathy.

STUDY DESIGN

Fetal hydrolaparoscopy-endoscopic fetal cystotomy was performed in a patient with a markedly thickened bladder that could not be entered percutaneously. A peritoneoamniotic (bridge) shunt was also placed. Fetal hydrolaparoscopy-endoscopic fetal cystotomy was performed in a second patient with a collapsed bladder from a previous vesicocentesis, because vesicoinfusion resulted in further ascites. Fetal cystoscopy was performed after endoscopic fetal cystotomy, and posterior urethral valves were ablated with neodymium:yttrium-aluminum-garnet laser energy. A vesicoamniotic shunt was left in place.

RESULTS

Adequate bladder drainage was obtained in both cases. The first baby required bilateral nephrotomy and a permanent cystotomy at birth and is scheduled for a bladder expansion procedure at the age of year. The second patient had premature rupture of membranes and fetal death from treatment of this complication 5 days after the original procedure.

CONCLUSION

Fetal hydrolaparoscopy-endoscopic fetal cystotomy can be performed in complicated cases of lower obstructive uropathy. The procedure involves the creation of a defect in the bladder dome under direct endoscopic visualization within a spontaneous or intentional hydroperitoneum. Peritoneoamniotic shunting, vesicoamniotic shunting, or ablation of posterior urethral valves may then be performed. Fetal hydrolaparoscopy-endoscopic fetal cystotomy should be reserved only for complicated cases of lower obstructive uropathy in which conventional vesicoamniotic shunting is not safely possible. Further experience with fetal hydrolaparoscopy-endoscopic fetal cystotomy is necessary to establish its risks and benefits.

[Posterior urethral valve: determining factors of long-term results]

Posterior urethral valves (PUV) is the most common congenital urine flow impairment in boys. Long-term prognosis involves: renal function impaired in 30 to 50% of PUV and leading to hyperdiuresis, low GFR and acidosis; bladder urodynamics impaired in 75% of PUV with abnormal urine storage, abnormal micturition and vesicoureteric reflux. Incontinence and recurrent urinary tract infections commonly reflect bladder and renal failures; abnormal bladder outlet leads to incontinence and abnormal ejaculation. The roles of antenatal treatments (vesico-amniotic shunts), neonatal treatments (resuscitation and endoscopic treatment of PUV) and long-term treatments (urinary diversions, bladder augmentation, alpha blockers, anticholinergic, dialysis and renal transplant) in the long-term outcomes of PUV are reviewed.

Successful in utero endoscopic ablation of posterior urethral valves: a new dimension in fetal urology

Fetal lower urinary tract obstructive uropathy, when associated with oligohydramnios, is usually associated with a poor outcome. We present a case of successful in utero endoscopic ablation of posterior urethral valves in which the infant survived the neonatal period without evidence of renal dysplasia. The role, indications, and potential benefits of this novel technique are discussed.

Fetal interventions for obstructive uropathy

Obstructive uropathy is a significant source of morbidity and mortality in the neonate and infant, despite advances in postnatal management. Diagnosis is typically made early in the second trimester on the basis of sonographic measurements. In utero therapy holds promise for improved outcomes by preventing progressive urinary tract damage and permitting drainage of urine into the amniotic space to minimize the pulmonary sequelae of oligohydramnios. Multiple studies with animal models have showed the benefits of midgestational intervention, but large prospective, randomized studies have not yet been performed to confirm these findings in humans. Standardization of the diagnostic evaluation allows for refined patient selection, resulting in improved postnatal outcomes after fetal vesicoamniotic shunting. Research into the role of specific growth factors and immunoproteins in renal development and function may further improve patient selection and outcome. This article reviews diagnosis, technique, and outcomes for fetal treatment of obstructive uropathy.

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.

Fetal uropathy

Our understanding of the causes, mechanisms, and prenatal management of fetal obstructive uropathy has increased significantly. Improved methods of prenatal evaluation have allowed the better selection of fetuses for invasive therapy, and studies indicate better survival and renal outcomes in carefully selected cases. New biological markers in fetal urine may provide a better understanding of the pathological processes of renal damage, additional prognostic markers, and lead to non-surgical approaches to preventing renal damage.

Prune belly syndrome with penile and urethral agenesis: report of a case

The authors report the case of an infant born with prune belly syndrome associated with penile and urethral agenesis. At 15 weeks' gestation, antenatal ultrasonography showed a fetal giant bladder, congenital hydronephrosis, and oligohydramnios, and at 17 weeks' gestation, a fetal vesicoamniotic shunt operation was performed. A boy was born at 33 weeks' gestation with prune belly syndrome, an anocutaneous fistula, and penile agenesis. A cystostomy and cut-back operation were performed immediately, showing urethral agenesis, no urethral opening, and left renal hypoplasia. Thereafter, his renal system began functioning normally, and a urinary tract infection resolved. The authors speculate that the prune belly syndrome in this patient was caused by penile and urethral agenesis.

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.

Development of human fetal kidney in obstructive uropathy: correlations with ultrasonography and urine biochemistry

In utero urethral obstruction results in bilateral hydronephrosis and severe fetal and post-natal morbidity and mortality. Obstetrical management depends on the indirect evaluation of fetal renal function by ultrasonography and biochemical analysis. No direct evaluation of the severity and possible reversibility of renal lesions is available. In this paper we analyzed kidneys from 34 fetuses (14 to 37 gestational weeks) in which (1) isolated bilateral urinary tract obstruction had been detected in utero by sonography, and (2) the severity of sonographic and biochemical prognostic indicators led to the indication of termination of pregnancy or to perinatal death. Pure hydronephrosis was observed in two young fetuses [14 and 20 gestational weeks (GW)] and was associated with regressive changes in two others. In contrast, a wide spectrum of dysplastic renal lesions was present in 30 fetuses and was classified into four subgroups according to the association of dysplasia, hypoplasia and cysts. They had the following characteristics in common: (1) premature cessation of nephrogenesis assessed by the medullary ray counting method; (2) early disappearance or myofibroblastic differentiation of metanephric blastema; (3) early increase in interstitial mesenchyme with widespread expression of alpha-smooth muscle actin by mesenchymal cells; (4) frequent absence of classical criteria of dysplasia (nests of cartilage were observed in only 5 fetuses); (5) an identification, based upon the detection of alpha-smooth muscle actin expression, of the muscular phenotype of mesenchymal cells encircling primitive ducts. In conclusion, (1) the value of prognostic markers in fetuses less than 20 GW should be reconsidered; (2) after 20 GW there is a good correlation between markers predicting poor prognosis and the severity of renal lesions; (3) hypoplasia with disappearance of blastema cells, dysplasia and early interstitial fibrosis are evidence of the irreversibility of renal lesions and preclude any possibility of new nephron formation; (4) these findings suggest that most surgical in utero procedures are performed when irreversible renal lesions have developed.

Prenatal evaluation of fetal anomalies

Advances in sonographic imaging have allowed for detailed examination of the fetus. A wide range of abnormalities of the fetal central nervous system, chest, gastrointestinal tract, genitourinary system, and skeleton are detectable by prenatal sonography. This article reviews the sonographic findings and prognostic implications of these abnormalities.

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.

In fetuses with isolated hydronephrosis, urinary beta 2-microglobulin and N-acetyl-beta-D-glucosaminidase (NAG) have a limited role in the prediction of postnatal renal function

Seventy-one fetal urine samples were taken from the bladder or renal pelvis of 33 fetuses at 13-36 weeks' gestation with a diagnosis of urinary tract anomaly. Severe isolated hydronephrosis in the absence of an enlarged bladder was the indication for sampling in 12/33 fetuses (26 samples), who were retrospectively classified into three groups: normal, intermediate, and dysplastic, based on the evaluation of postnatal renal function or histology. For all samples, urinary sodium (Na+), calcium (Ca2+), creatinine, beta 2-microglobulin, and N-acetyl-beta-D-glucosaminidase (NAG) were measured. Among the 71 fetal urine samples, both beta 2-microglobulin and NAG correlated inversely with gestational age, Na+, and Ca2+, but not with creatinine concentrations. However, the correlation of urinary beta 2-microglobulin with gestational age was dependent on the Na+ and Ca2+ concentrations, whereas urinary NAG correlated significantly with urinary Na+ and Ca2+, and also with gestational age. In fetuses with isolated hydronephrosis, only Na+, and not Ca2+, was significantly related to both beta 2-microglobulin and NAG. Only Na+ and beta 2-microglobulin were significantly, and similarly, higher in both dysplastic and intermediate kidneys when compared with fetuses with normal postnatal function. If only the last urine sampled was considered, there was overlapping of all parameters in the three groups. In isolated hydronephrosis, only the most extreme forms of renal failure might be suggested by elevated levels of Na+, Ca2+, beta 2-microglobulin, and NAG, without an obvious superiority of any of these parameters.

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.

Prenatal diagnosis and the pediatric surgeon: the impact of prenatal consultation on perinatal management

PURPOSE

Pediatric surgeons are increasingly called on by obstetrical colleagues to counsel parents about the implications of a prenatal ultrasound finding. Our understanding of the natural history of many prenatally diagnosed surgical conditions has grown significantly in recent years. Whether prenatal surgical consultation can influence perinatal course had not been investigated.

METHODS

During an 21-month period, 12,865 prenatal ultrasound studies were performed on a total of 4,551 patients, and 221 prenatal surgical consultations were obtained through a newly established fetal treatment program at a tertiary care prenatal diagnostic center. To evaluate the impact of prenatal pediatric surgical consultation on perinatal course, the authors reviewed changes in management including termination of pregnancy, in utero intervention, and altered site, mode, or timing of delivery.

RESULTS

Two hundred twenty-one fetuses were referred for consultation; their 234 congenital anomalies included genitourinary (36%), thoracic (16%), intraabdominal (14.5%), abdominal wall (10.6%), neurological (9%), skeletal (6%), and head and neck (2.5%) defects; 2.5% had tumors and 2.5% were twin pregnancies. Pregnancy was terminated in 9.5% of cases, because of patient request, chromosomal abnormality, or dismal prognosis. In 3.6%, the decision to terminate was changed as a result of consultation. Site of delivery was changed as a result of consultation in 37% to facilitate postnatal evaluation and initiate immediate treatment. Mode of delivery was changed in 6.8% to prevent dystocia, hemorrhage into a tumor, as in sacrococcygeal teratoma, or to provide an emergency airway, as in cervical teratoma. The timing of delivery was changed in 4.5% to avoid further damage to fetal organs in cases of obstructive uropathy, gastroschisis, sacrococcygeal teratoma with high-output failure, and hydrocephalus. Five percent (11) underwent treatment in utero for fetal hydrothorax, obstructive uropathy, twin-twin transfusion syndrome, or lymphangioma. The overall perinatal mortality rate was 2.5%.

CONCLUSION

Prenatal pediatric surgical consultation may have a significant impact on the perinatal management of the fetus with a surgically correctable congenital anomaly. Providing obstetric colleagues and families with valuable insight into the surgical management of anomalies allows fetal intervention when appropriate, and delivery in an appropriate setting, by the safest mode of delivery, and at the gestational age appropriate to minimize effects of the anomaly.

Endoscopic intrauterine fetal therapy: a monkey model

OBJECTIVES

Prenatal ultrasonographic investigations have led to an increasing number of prenatally detected abnormalities, of which a large number involves the urogenital tract. This study was performed to evaluate if endoscopic intra-amniotic access is possible in primates.

METHODS

In 10 midtrimester rhesus monkeys (Macaca mulatta), endoscopic intrauterine fetoscopy was performed with three access cannulas. Using a Seldinger technique, a vascular access system, and a pediatric laparoscopy set, intra-amniotic inspection was attempted. Fetal growth throughout pregnancy was monitored by ultrasonographic measurements of fetal biometry.

RESULTS

Intrauterine access could successfully be achieved in 10 rhesus monkeys with three cannulas. After partial amniotic fluid exchange, adequate fetoscopy was always possible. Two monkeys aborted on the second and sixth postoperative days. Serial ultrasonographic investigations for fetal biometry showed no disturbance of the intrauterine growth patterns in the remaining 8 monkeys.

CONCLUSIONS

We currently conclude that the rhesus monkey model for experimental intrauterine endoscopic surgery may be suitable for study of the developmental abnormalities of the genitourinary tract.