10-Year Experience With Prenatal Intervention for Hydronephrosis

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.

Antenatal Determinants of Long-Term Kidney Outcome in Boys with Posterior Urethral Valves

Background: Posterior urethral valves (PUV) are the most important cause of end-stage renal disease (ESRD) in young boys. The objective of this report was to define the antenatal determinants of long-term postnatal renal outcome in this condition. Design: This was a retrospective cohort analysis. The primary outcome was the development of ESRD defined as starting dialysis or receiving a preemptive kidney transplant. Results: Eighty-two cases of PUV were identified, with 17 (21%) developing ESRD at 6.1 ± 7.1 years. Cases developing ESRD were more likely diagnosed antenatally (41 vs. 19%, p = 0.05), had a younger gestational age (35.5 ± 3.4 weeks vs. 37.3 ± 2.1 weeks, p = 0.02), and on antenatal ultrasound scan were more likely to have oligohydramnios (60 vs. 26%, p = 0.02), renal cortical cysts (47 vs. 17%, p = 0.02), and the combination of oligohydramnios, renal cortical cysts, and increased renal echogenicity (47 vs. 9%, p = 0.002). Conclusions: In boys with PUV, decreased gestational age, oligohydramnios, renal cysts, and the combination of oligohydramnios, cortical cysts, and echogenic kidneys were associated with ESRD, while the combination was an independent predictor of poor long-term postnatal kidney function.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Fetal lower urinary tract obstruction

The authors present an overview of the prenatal diagnosis, evaluation, contemporary intervention, and antenatal management of lower urinary tract obstruction. They review early experimental models that confirmed the relation between urinary tract obstruction and renal fibrocystic dysplasia and that early in utero relief of the obstruction could prevent irreversible renal injury. Subsequent studies of the electrolyte and protein concentrations in fetal urine from human cases established prognostic threshold values and helped to develop an algorithm to select candidates for antenatal therapy. Although shunting has improved survival, long-term morbidities remain a significant challenge.

Abnormalities of the fetal bladder

This review aims to outline the management of a fetus in whom a distended bladder or an absent bladder has been identified during prenatal fetal screening. The causes, pre-delivery and immediate post-delivery treatment options are discussed, as well as prognosis.

Management of fetal hydronephrosis

Prenatally detected hydronephrosis has become a common diagnosis for both pediatric nephrologists and urologists. Hydronephrosis is most commonly assessed by the Society for Fetal Urology grading system or anterior-posterior diameter of the renal pelvis in the transverse plane. Some cases of bilateral obstruction, most commonly from posterior urethral valves, can be life-threatening and require close monitoring or, occasionally, fetal intervention. The majority are unilateral and of no threat to the growing fetus. The crux of postnatal management is the separation of the minority of patients whose renal function is at risk from the majority who will suffer no renal consequences. This management involves a regimen of ultrasounds, voiding cystourethrograms, and nuclear renograms for diagnosis and surveillance. Recent literature has been aimed at the timing and necessity of these studies in order to minimize extraneous studies without compromising renal function.

Posterior urethral valve: Outcome of antenatal intervention

INTRODUCTION AND AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Successful vesicoamniotic shunting of posterior urethral valves in the first trimester of pregnancy

Prenatal ultrasonography early in gestation allows diagnosis of posterior urethral valves. We report on a fetus with posterior urethral valves treated using vesicoamniotic shunting at 13 + 5 weeks' gestation. A double-basket catheter was used for shunting. A 2582-g male neonate was delivered at 33 weeks' gestation, and the infant continued to show normal renal function at 3 years of age. To the best of our knowledge this is the first report of successful vesicoamniotic shunt placement using a double-basket catheter in the first trimester of pregnancy.

Prenatal puncture of a unilateral hydronephrosis leading to fetal urinoma and postnatal nephrectomy

Fetal pelvicaliceal dilatation due to ureteropelvic junction obstruction is the most common cause of antenatal hydronephrosis; it rarely leads to a spontaneous rupture resulting in urinoma formation. Antenatal intervention has been recommended only in those cases of large urinomas that seem to interfere with the function of other organ systems (eg, pulmonary hypoplasia secondary to diaphragmatic elevation). We report the case of a fetal intervention (transuterine puncture) in a unilateral massive hydronephrosis leading to a perirenal urinoma and the preterm birth of a female infant. Postnatally, mechanical ventilation and oxygen were required, as was forced percutaneous urinoma drainage. Evaluation revealed a fistula formation between the perirenal space and the kidney's collecting system, possibly due to the fetal intervention. Unfortunately the kidney function was very poor, and surgery to remove the impaired kidney and the urinoma was performed. We discuss the possible effects of fetal intervention in cases of obstructive uropathy and the postnatal risks associated with it.

Perinatal obstructive nephropathy

Significant advances have been made recently in elucidating the cellular consequences of urinary tract obstruction during renal development. Urinary tract obstruction impairs growth and maturation of the kidney, and can also cause renal maldevelopment. This includes a reduction in the number of nephrons, tubular atrophy, and progressive interstitial fibrosis. Apoptosis (programmed cell death) accounts for much of the loss of tubular epithelial cells. Factors contributing to apoptosis include stretching of cells in dilated tubules, altered renal production of growth factors, and infiltration of the renal interstitium by macrophages. Two major controversies remain regarding the surgical management of congenital obstructive nephropathy: first, which fetuses with bladder outlet obstruction should undergo prenatal intervention, and second, which infants should undergo early pyeloplasty for ureteropelvic junction obstruction? Even after successful surgery for congential obstructive nephropathy, all patients should be followed for hypertension, proteinuria, or renal deterioration.

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 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.

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.

Postnatal management of hydronephrosis diagnosed in utero

In this review we identify the causes of antenatal hydronephrosis and detail management options. A large majority of these patients can be treated safely and effectively after birth.