Increased Renal Echogenicity: A Sonographic Sign for Differentiating Between Obstructive and Nonobstructive Etiologies of in Utero Bladder Distension

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.

Neurodevelopmental Outcome in Infants with Lower Urinary Tract Obstruction Based on Different Degrees of Severity

OBJECTIVE

To determine postnatal neurodevelopmental (ND) outcomes for children with congenital lower urinary tract obstruction (LUTO) based on disease severity.

METHODS

Twenty male infants with LUTO were classified prenatally as Stage 1 (normal amniotic fluid and renal function; n = 5), Stage 2 (signs of obstruction with preserved renal function; n = 13), and Stage 3 (signs of severe renal damage; n = 2). ND status was assessed using the Developmental Profile-3 test in 5 developmental domains (physical, adaptive behavior, social-emotional, cognitive, and communication). Each domain was considered to be delayed if standard scores were 2 or more SD below the mean. ND outcomes were compared between cases with an expected normal renal function (LUTO Stage 1) and those with impaired renal function (LUTO Stages 2 and 3). Results from cases with Stage 2 were also compared to those from Stage 3. ORs were calculated to predict risk for adverse ND outcome for each domain considering prenatal and postnatal factors.

RESULTS

Gestational age (GA) at the diagnosis of LUTO was similar between both groups (Stage 1: 24.85 ± 7.87 vs. Stages 2 and 3: 21.4 ± 4.31 weeks; p = 0.24). Twelve of 15 cases with Stage 2 or 3 underwent vesicoamniotic shunt placement compared to none of Stage 1 fetuses (p < 0.01). No differences in GA at delivery were detected between the groups (37.9 ± 1.6 vs. 35.1 ± 3.6 weeks; p = 0.1). One of the infants in the Stage 2 and 3 groups received a kidney transplant during follow-up. One case (20%) from Stage 1 group required dialysis during the first 6 months of life, and 1 case from Stage 2 to 3 group required it during the first 6 months (p = 1.0), whereas 3 additional cases needed dialysis from 6 to 24 months (p = 0.6). Mean age at Developmental Profile 3 (DP-3) testing was 20.3 ± 12.3 months (Stage 1: 11.2 ± 8.6 vs. Stages 2 and 3: 23.4 ± 13.4 months; p = 0.07). Fifteen of the 20 patients (75%) had no ND delays. Of the 5 patients with ND delays, 4 received dialysis. No differences in ND outcomes between infants with LUTO Stage 1 and those with Stages 2 and 3 were detected except for a trend toward better physical development in Stage 1 (102.6 ± 11.6 vs. 80.7 ± 34.9; p = 0.05). Infants diagnosed with LUTO Stage 3 showed significantly lower adaptive scores than those diagnosed with Stage 2 (Stage 2: 101.9 ± 22.3 vs. Stage 3: 41.5 ± 30.4; p = 0.04) and a nonsignificant trend for lower results in physical (85.8 ± 33.0 vs. 47.5 ± 38.9; p = 0.1) and socio-emotional (94.7 ±17.9 vs. 73.5 ± 13.4; p = 0.1) domains. Infants who received dialysis showed 15-fold increased risk (95% CI 0.89-251) for delayed socio-emotional development (p = 0.06). Diagnosis of fetal renal failure increased the risk for delays in the adaptive domain 30-fold (95% CI 1.29-93.1; p = 0.03). Infants with abnormal renal function had 19 times (95% CI 1.95-292) increased risk for delays in the physical domain (p = 0.03).

CONCLUSIONS

While most patients with LUTO do not exhibiting ND delays, our results support the importance of ND monitoring, especially in severe forms of LUTO, as increased severity of this condition may be associated with poorer ND outcomes.

Fetal megacystis: A systematic review

Fetal megacystis is variably defined and understood. The literature on fetal megacystis was systematically reviewed, focusing on prenatal diagnosis, associations and outcomes. This yielded a total of 18 primary references and eight secondary references. Fetal megacystis has an estimated first-trimester prevalence of between 1:330 and 1:1670, with a male to female ratio of 8:1. In the first trimester, megacystis is most commonly defined as a longitudinal bladder dimension of ≥7 mm. Later in pregnancy, a sagittal dimension (in mm) greater than gestational age (in weeks) + 12 is often accepted. Megacystis can be associated with a thickened bladder wall, which has been objectively defined as >3 mm. Oligohydramnios is present in approximately half of all cases. The most common underlying diagnosis is posterior urethral valves (57%), followed by urethral atresia/stenosis (7%), prune belly syndrome (4%), megacystis-microcolon-intestinal-hypoperistalsis syndrome (MMIHS) (1%), and cloacal anomalies (0.7%). Karyotype anomalies are found in 15%, and include trisomy 18, trisomy 13 and trisomy 21. Ultrasound imaging alone is often insufficient to enable a definitive diagnosis, although it may indicate that a specific diagnosis is more likely. Overall, about 50% of reported fetuses with megacystis are terminated, but this proportion varies considerably between countries and over time. Prognostic stratification is evolving, with the most important factors being oligohydramnios, gestational age at diagnosis, degree of bladder enlargement, renal hyperechogenicity, karyotype, and sex.

CONCLUSIONS

This review demonstrated some consensus on the ultrasound criteria for defining fetal megacystis, and illustrated the spectrum of pathologies and their relative frequencies that can cause this condition. It also underlined important associated karyotype anomalies. To progress understanding of the natural history of enlarged fetal bladders, more accurate diagnostics are required, and risk stratification needs to be refined to facilitate prenatal counseling.

Outcome in fetal lower urinary tract obstruction: a prospective registry study

OBJECTIVE

To describe influences on decision-making and prognostic variables in the prenatal management of fetal lower urinary tract obstruction (LUTO).

METHODS

This was a prospective registry study of pregnant women with a male fetus with LUTO from centers within the British Isles and The Netherlands. Women and/or their clinicians were given the treatment option of either conservative management or vesicoamniotic shunting (VAS). Baseline characteristics of women in the registry, reasons for entry to the registry and pregnancy outcomes were assessed. The main study outcomes were survival to 28 days after delivery, further survival to 2 years and renal function. Logistic regression analysis was used to examine prognostic variables that affected outcome. Results were compared with those of women in a randomized controlled trial (RCT) who were allocated randomly to a treatment option.

RESULTS

Forty-five women were registered, of whom 78% (35/45) underwent conservative management. Twenty-seven women entered the registry owing to their clinician's preference for management and 18 because of their own preference. Compared to the conservative-management group of the RCT, a higher proportion of women in the registry opting for conservative management had a normal amniotic fluid volume at diagnosis (P = 0.05) and a diagnosis of LUTO ≥ 24 weeks' gestation (P = 0.003). On multivariable logistic regression analysis, these variables showed a significant association with perinatal survival (P < 0.001). Survival to 28 days after delivery was higher in the conservative-management group, at 69% (24/35), compared to 40% (4/10) in the VAS group (P = 0.02) but this difference had limited statistical significance owing to small study size (relative risk, 0.58 (95% CI, 0.26-1.29); P = 0.14).

CONCLUSION

In our prospective registry, the majority of fetuses with LUTO received conservative management, which was associated with better short- and long-term outcomes. A significant proportion of these pregnancies had normal amniotic fluid volume and a gestational age at diagnosis of ≥ 24 weeks, characteristics shown to be associated with improved survival.

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.

Laser Ablation of Posterior Urethral Valves by Fetal Cystoscopy

Objective: To report the results of fetal cystoscopic laser ablation of posterior urethral valves (PUV) in a consecutive series in two referral centers. Methods: Twenty pregnant women with a presumptive isolated PUV were treated with fetal cystoscopy under local anesthesia. Identification and fulguration of the PUV by one or several firing-contacts with diode laser were attempted. Perinatal and long-term outcomes were prospectively recorded. Results: The median gestational age at procedure was 18.1 weeks (range 15.0-25.6), and median operation time was 24 min (range 15-40). Access to the urethra was achieved in 19/20 (95%) cases, and postoperative, normalization of bladder size and amniotic fluid was observed in 16/20 (80%). Overall, there were 9 (45%) terminations of pregnancy and 11 women (55%) delivered a liveborn baby at a mean gestational age of 37.3 (29.1-40.2) weeks. No infants developed pulmonary hypoplasia and all were alive at 15-110 months. Eight (40% of all fetuses, 72.7% of newborns) had normal renal function and 3 (27.3%) had renal failure awaiting renal transplantation. Conclusion: Fetoscopic laser ablation for PUV can achieve bladder decompression and amniotic fluid normalization with a single procedure in selected cases with anyhydramnios. There is still a significant risk of progression to renal failure pre or postnatally.

A systematic review on the accuracy of diagnostic procedures for infravesical obstruction in boys

Background

Infravesical obstruction leads to kidney and bladder dysfunction in a significant proportion of boys. The aim of this review is to determine the value of diagnostic tests for ascertainment of infravesical obstruction in boys.

Methodology

We searched PubMed and EMBASE databases until January 1, 2013, to identify papers that described original diagnostic accuracy research for infravesical obstruction in boys. We extracted information on (1) patient characteristics and clinical presentation of PUV and (2) diagnostic pathway, (3) diagnostic accuracy measures and (4) assessed risk of bias.

Principal Findings

We retrieved 15 studies describing various diagnostic pathways in 1,189 boys suspected for infravesical obstruction. The included studies reflect a broad clinical spectrum of patients, but all failed to present a standardised approach to confirm the presence and severity of obstruction. The risk of bias of included studies is rather high due to work-up bias and missing data.

Conclusions

As a consequence of low quality of methods of the available studies we put little confidence in the reported estimates for the diagnostic accuracy of US, VCUG and new additional tests for ruling in or ruling out infravesical obstruction. To date, firm evidence to support common diagnostic pathways is lacking. Hence, we are unable to draw conclusions on diagnostic accuracy of tests for infravesical obstruction. In order to be able to standardise the diagnostic pathway for infravesical obstruction, adequate design and transparent reporting is mandatory.

Percutaneous vesicoamniotic shunting versus conservative management for fetal lower urinary tract obstruction (PLUTO): a randomised trial

BACKGROUND

Fetal lower urinary tract obstruction (LUTO) is associated with high perinatal and long-term childhood mortality and morbidity. We aimed to assess the effectiveness of vesicoamniotic shunting for treatment of LUTO.

METHODS

In a randomised trial in the UK, Ireland, and the Netherlands, women whose pregnancies with a male fetus were complicated by isolated LUTO were randomly assigned by a central telephone and web-based randomisation service to receive either the intervention (placement of vesicoamniotic shunt) or conservative management. Allocation could not be masked from clinicians or participants because of the invasive nature of the intervention. Diagnosis was by prenatal ultrasound. The primary outcome was survival of the baby to 28 days postnatally. All primary analyses were done on an intention-to-treat basis, but these results were compared with those of an as-treated analysis to investigate the effect of a fairly large proportion of crossovers. We used Bayesian methods to estimate the posterior probability distribution of the effectiveness of vesicoamniotic shunting at 28 days. The study is registered with the ISRCTN Register, number ISRCTN53328556.

FINDINGS

31 women with singleton pregnancies complicated by LUTO were included in the trial and main analysis, with 16 allocated to the vesicoamniotic shunt group and 15 to the conservative management group. The study closed early because of poor recruitment. There were 12 livebirths in each group. In the vesicoamniotic shunt group one intrauterine death occurred and three pregnancies were terminated. In the conservative management group one intrauterine death occurred and two pregnancies were terminated. Of the 16 pregnancies randomly assigned to vesicoamniotic shunting, eight neonates survived to 28 days, compared with four from the 15 pregnancies assigned to conservative management (intention-to-treat relative risk [RR] 1·88, 95% CI 0·71-4·96; p=0·27). Analysis based on treatment received showed a larger effect (3·20, 1·06-9·62; p=0·03). All 12 deaths were caused by pulmonary hypoplasia in the early neonatal period. Sensitivity analysis in which non-treatment-related terminations of pregnancy were excluded made some slight changes to point estimates only. Bayesian analysis in which the trial data were combined with elicited priors from experts suggested an 86% probability that vesicoamniotic shunting increased survival at 28 days and a 25% probability that it had a large, clinically important effect (defined as a relative increase of 55% or more in the proportion of neonates who survived). There was substantial short-term and long-term morbidity in both groups, including poor renal function-only two babies (both in the shunt group) survived to 2 years with normal renal function. Seven complications occurred in six fetuses from the shunt group, including spontaneous ruptured membranes, shunt blockage, and dislodgement. These complications resulted in four pregnancy losses.

INTERPRETATION

Survival seemed to be higher in the fetuses receiving vesicoamniotic shunting, but the size and direction of the effect remained uncertain, such that benefit could not be conclusively proven. Our results suggest that the chance of newborn babies surviving with normal renal function is very low irrespective of whether or not vesicoamniotic shunting is done.

FUNDING

UK National Institute of Health Research, Wellbeing of Women, Hannah Eliza Guy Charity (Birmingham Children's Hospital Charity).

Spontaneous resolution of isolated congenital megacystis: the incredible shrinking bladder

Isolated congenital megacystis represents a rare variant of fetal megacystis without other associated anomalies. The etiology is unclear, and various management strategies have been proposed. We report a case of isolated congenital megacystis that resolved over the first year of life with observation alone. Considerations for the evaluation and management of this rare entity are discussed.

Urinary proteome analysis in congenital bilateral hydronephrosis

OBJECTIVE

A proteomics strategy was applied to map protein changes in urine after relief of congenital bilateral hydronephrosis to identify proteins correlated with the pathophysiological processes in congenital obstructive nephropathy as potential urinary biomarkers.

MATERIAL AND METHODS

Urine samples from 10 infants with bilateral abnormal drainage from the kidneys were collected at the time of relief from obstruction, and after 2 and 4 weeks. Proteomics techniques were used on samples from three patients for identification of protein changes between the three time-points, and enzyme-linked immunosorbent assay (ELISA) was used on samples from all 10 patients for validation of five selected proteins.

RESULTS

Mass spectrometry quantified 315 protein hits, out of which 33 proteins showed significantly changed urinary excretion between the time-points. Validation by ELISA showed high urinary excretion of fibrinogen, plasminogen, transthyretin and transferrin at the time of relief from obstruction, followed by a significant reduction. In contrast, Tamm-Horsfall protein exhibited the reverse pattern.

CONCLUSION

Using a mass spectrometry-based proteomics approach, this study identified 33 proteins related to congenital bilateral hydronephrosis, and pinpointed a panel of five proteins consistently linked to this congenital kidney disorder as potential urinary biomarkers.

Feasibility of measuring 3-dimensional renal parenchymal volume to predict postnatal renal function in near-term fetuses with congenital hydronephrosis: a preliminary study

OBJECTIVES

The purposes of this study were to evaluate the feasibility of predicting kidney function using the fetal renal parenchymal volume as determined by prenatal 3-dimensional (3D) sonography and to determine the association among the prenatal renal pelvic diameter, renal parenchymal volume, and postnatal renal function in near-term fetuses with unilateral hydronephrosis.

METHODS

This retrospective study included 42 kidneys (21 normal and 21 hydronephrotic) from 21 fetuses between 30 and 39 weeks' gestation. We used the extended imaging virtual organ computer-aided analysis (XI VOCAL; 10 planes) technique for the prenatal volumetric measurements, and postnatal renal function was estimated using renal scintigraphy. An independent-samples Student ttest, Spearman's rank correlation, and simple linear regression were used for the statistical analyses. Reproducibility was confirmed with a paired Student t test and intraclass correlation coefficients.

RESULTS

The renal pelvic diameter correlated well with the renal parenchymal volume Spearman ρ = 0.765; P < .001). The postnatal renal function correlated with the adjusted 3D renal parenchymal volume (Spearman ρ = -0.321; P = .043) but did not correlate with the prenatal renal pelvic diameter (Spearman ρ = -0.291; P = .062).

CONCLUSIONS

This preliminary study showed that 3D renal parenchymal volume could be a coparameter for predicting postnatal renal function with the renal pelvic diameter. Further studies in a larger population are required to obtain robust results.

CONGENITAL URINARY BLADDER OUTLET OBSTRUCTION

The term congenital ‘bladder outlet obstruction (BOO)’ describes the collection of conditions in which the normal, urethral egress of urine from the fetal bladder is impaired. The term is interchangeable with fetal ‘lower urinary tract obstruction’, as used by other authors. After considering normal urinary tract embryology, we describe the epidemiology of congenital BOO and the primary anatomical disorders associated with it. We then proceed to describe its fetal and postnatal clinical manifestations and then consider therapies and interventions which have been used to manage the condition. We not only focus on urethral and bladder disease with constitutes BOO itself, but also describe associated kidney disorders which, via chronic renal excretory failure, are important causes of morbidity. Rather than provide an exhaustive review, we emphasise studies published in the last decade, and therefore readers are referred to other reviews citing numerous earlier references.

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.

Congenital urinary tract obstruction

Congenital urinary tract obstruction is a heterogenous condition with a varying natural history. Accurate diagnosis within the late-first and second trimesters allows for counselling of the parents and planning of multi-disciplinary care for the pregnancy and newborn. Antenatal investigations to predict postnatal renal function are of varying accuracy. However, some factors have been shown to be predictive of poor outcome in terms of renal function at birth and infancy. There is the possibility of in-utero intervention in these fetuses.

Fetal lower urinary tract obstruction

Fetal lower urinary tract obstruction affects 2.2 per 10,000 births. It is a consequence of a range of pathological processes, most commonly posterior urethral valves (64%) or urethral atresia (39%). It is a condition of high mortality and morbidity associated with progressive renal dysfunction and oligohydramnios, and hence fetal pulmonary hypoplasia. Accurate detection is possible via ultrasound, but the underlying pathology is often unknown. In future, magnetic resonance imaging (MRI) may be increasingly used alongside ultrasound in the diagnosis and assessment of fetuses with lower urinary tract obstruction. Fetal urine analysis may provide improvements in prenatal determination of renal prognosis, but the optimum criteria to be used remain unclear. It is now possible to decompress the obstruction in utero via percutaneous vesico-amniotic shunting or cystoscopic techniques. In appropriately selected fetuses intervention may improve perinatal survival, but long-term renal morbidity amongst survivors remains problematic.

Current diagnosis and management of fetal genitourinary abnormalities

Prenatal assessment with ultrasonography provides excellent imaging of fluid-filled structures (eg, hydronephrosis, renal cysts, and dilated bladder) and renal parenchyma. This information allows for the generation of a differential diagnosis, identification of associated anomalies, and assessment of the prenatal and postnatal risks of a given anomaly. This enhances parental education and prenatal and postnatal planning. This article discusses the current methods of diagnosis and management of fetal genitourinary anomalies, and also the postnatal evaluation and treatment of these conditions.

Correlation between ultrasound and anatomical findings in fetuses with lower urinary tract obstruction in the first half of pregnancy

OBJECTIVE

The prognosis of fetal lower urinary tract obstruction (LUTO) depends upon renal function and also upon the underlying etiology. Precise identification of the latter remains a challenge antenatally. Our objective was to examine the underlying pathology in male fetuses with sonographic evidence of severe and isolated LUTO.

METHODS

Detailed postmortem examination was carried out after termination of pregnancy in 24 male fetuses presenting before 25 weeks of gestation with ultrasound evidence of isolated severe LUTO.

RESULTS

All fetuses had megacystis and hyperechogenic kidneys. There was anhydramnios/oligohydramnios and pelvicalyceal dilatation in 20 and 15 cases, respectively. Posterior urethral valves (PUV) were suspected antenatally in 20 cases and urethral atresia was not suspected antenatally. However, postmortem examination of the urethra demonstrated atresia in six cases, severe stenosis in eight cases, PUV in nine cases and an apparently normal urethra in one case. Renal dysplasia was found in all cases but one. Urethral atresia was the most common urethral anomaly at 12-17 weeks. Hydronephrosis was more frequent in cases with PUV (8/9) and urethral stenosis (6/8) than with urethral atresia (0/6). In LUTO presenting in the first and second trimester, hyperechogenic kidneys were predictive of renal dysplasia in 95% of cases. The association of a sagittal diameter of the bladder of at least 40 mm with hydronephrosis before 28 weeks was predictive of PUV with a positive (PPV) and negative (NPV) predictive value of 44.4% and 66.6%, respectively. Absence of hydronephrosis and a sagittal diameter of the bladder of less than 40 mm were predictive of urethral atresia or stenosis with a PPV and NPV of 100% and 47.6%, respectively. The absence of hydronephrosis was predictive of urethral atresia with a PPV and NPV of 66.6% and 100%, respectively.

CONCLUSION

LUTO in a male fetus presenting with megacystis in the first or second trimester of pregnancy is as likely to reflect urethral atresia or stenosis as it is PUV. The size of the bladder and the presence of hydronephrosis should be considered in order to improve prenatal diagnosis and counseling.

Initial and long-term management of posterior urethral valves

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

Urinary effects of morphine in preterm infants

AIM

To describe the association between morphine administration in preterm infants, hydronephrosis, and renal dysfunction.

METHODS

The findings were based on serial ultrasound examinations and blood studies.

RESULTS

Two preterm infants had bladder distension and hydronephrosis after they received intravenous morphine for analgesia. Morphine was used at a low dose. Each patient had a normal urine output and normal serum creatinine before the signs and symptoms of urinary retention were observed. Within 24 h of morphine administration, each infant concurrently developed oliguria and elevation of the serum creatinine. Cessation of morphine and urinary drainage resulted in rapid and complete resolution of the hydronephrosis and the elevated creatinine.

CONCLUSION

Morphine, even at low dosages, can be associated with hydronephrosis in hospitalized preterm infants.

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.

Enlarged fetal bladders: aetiology, management and outcome

Ultrasound routinely identifies the fetal bladder from 10 weeks of gestation. Understanding the normal embryology of the fetal bladder forms the basis of understanding the mechanisms for pathology. Early onset megacystis <12 mm (maximum diameter) frequently regresses spontaneously however when associated with other structural abnormalities 40% are chromosomally abnormal. Survival in this group is rare and the underlying histopathology is of urethral fibrostenosis. Second and third trimester megacystic indicates a heterogenous group where a precise antenatal diagnosis may be impossible. A distended thick wall bladder associated with a dilated posterior urethra and oligohydramnios is pathonemonic of posterior urethral valves; without this combination of ultrasound signs the underlying pathology is less certain. Prediction of other aetiologies for the megacystis is less accurate but includes primary reflux, cloacal plate, urethral duplication and megacystic microcolon in the differential diagnosis. Robust published data is currently unavailable to define appropriate management for individual cases of megacystis. Therefore current best practice for antenatal management will be discussed.

Accuracy of renal-bladder ultrasonography as a screening method to suggest posterior urethral valves

PURPOSE

We determine the usefulness of ultrasonography as a screening modality to support the diagnosis of posterior urethral valves.

MATERIALS AND METHODS

A retrospective chart analysis was performed of 93 consecutive boys with newly diagnosed posterior urethral valves from August 1985 through February 1999. Of the 93 boys 65, including 62 who underwent renal and bladder ultrasonography, had preoperative renal sonography available and constitute our study population. Patient age range at presentation was newborn to 13 years, with 33 of the 65 boys presenting as infants (age 1 year or younger). Presentation included fetal hydronephrosis in 13 cases, urinary tract infection in 18, voiding dysfunction in 9, abdominal mass in 6, renal insufficiency in 5, failure to thrive in 4, hematuria in 1 and other in 9.

RESULTS

Preoperative sonography identified bilateral hydronephrosis in 48 boys (74%), unilateral hydronephrosis in 9 (14%) and no hydronephrosis in 8 (12%). Bladder sonography revealed an abnormal bladder (thickened, trabeculated and/or significantly distended) in 54 boys (87%). An abnormal bladder was seen in 43 of the 46 boys with bilateral hydronephrosis, 6 of 8 boys with unilateral hydronephrosis and 5 of 8 with normal upper tracts. Only 3 of the 62 boys (5%) had a normal upper tract and bladder. The sensitivity of renal ultrasonography in suspecting posterior urethral valves was 88%, while sensitivity of renal-bladder ultrasonography was 95%. When stratifying for age younger than 4 years and 4 or older, the sensitivity of predicting posterior urethral valves with renal-bladder ultrasonography was 87% and 98%, respectively.

CONCLUSIONS

While voiding cystourethrography remains the imaging gold standard for the diagnosis of posterior urethral valves, renal-bladder ultrasonography is an appropriate screening study for a boy suspected to have the condition. Renal-bladder ultrasonography may prove particularly useful in the evaluation of the boy with significant voiding dysfunction before deciding on a more invasive study, such as voiding cystourethrography.

Accuracy of renal-bladder ultrasonography as a screening method to suggest posterior urethral valves

PURPOSE

We determine the usefulness of ultrasonography as a screening modality to support the diagnosis of posterior urethral valves.

MATERIALS AND METHODS

A retrospective chart analysis was performed of 93 consecutive boys with newly diagnosed posterior urethral valves from August 1985 through February 1999. Of the 93 boys 65, including 62 who underwent renal and bladder ultrasonography, had preoperative renal sonography available and constitute our study population. Patient age range at presentation was newborn to 13 years, with 33 of the 65 boys presenting as infants (age 1 year or younger). Presentation included fetal hydronephrosis in 13 cases, urinary tract infection in 18, voiding dysfunction in 9, abdominal mass in 6, renal insufficiency in 5, failure to thrive in 4, hematuria in 1 and other in 9.

RESULTS

Preoperative sonography identified bilateral hydronephrosis in 48 boys (74%), unilateral hydronephrosis in 9 (14%) and no hydronephrosis in 8 (12%). Bladder sonography revealed an abnormal bladder (thickened, trabeculated and/or significantly distended) in 54 boys (87%). An abnormal bladder was seen in 43 of the 46 boys with bilateral hydronephrosis, 6 of 8 boys with unilateral hydronephrosis and 5 of 8 with normal upper tracts. Only 3 of the 62 boys (5%) had a normal upper tract and bladder. The sensitivity of renal ultrasonography in suspecting posterior urethral valves was 88%, while sensitivity of renal-bladder ultrasonography was 95%. When stratifying for age younger than 4 years and 4 or older, the sensitivity of predicting posterior urethral valves with renal-bladder ultrasonography was 87% and 98%, respectively.

CONCLUSIONS

While voiding cystourethrography remains the imaging gold standard for the diagnosis of posterior urethral valves, renal-bladder ultrasonography is an appropriate screening study for a boy suspected to have the condition. Renal-bladder ultrasonography may prove particularly useful in the evaluation of the boy with significant voiding dysfunction before deciding on a more invasive study, such as voiding cystourethrography.

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.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Prognostic value of initial renal ultrasound in patients with posterior urethral valves

PURPOSE

Increased cortical echogenicity and loss of corticomedullary differentiation on the initial renal ultrasound study are said to be predictive of poor renal function in patients with posterior urethral valves. We reviewed ultrasound results in a group of patients with posterior urethral valves to test this hypothesis.

MATERIALS AND METHODS

We reviewed the radiology records of 19 patients in year 1 of life with posterior urethral valves seen since 1976 for whom records were available. The degree of corticomedullary differentiation and cortical echogenicity was compared with serum creatinine after 4 days of catheter drainage and creatinine clearance at the most recent followup.

RESULTS

Median followup was 96 months. At the last followup the sensitivity, specificity, and positive and negative predictive values of increased cortical echogenicity and loss of corticomedullary differentiation for predicting creatinine clearance less than 69 ml. per minute per 1.73 m.2 were 90, 57, 75 and 80, and 100, 33, 71 and 100%, respectively.

CONCLUSIONS

Increased cortical echogenicity and loss of corticomedullary differentiation are relatively insensitive predictors of eventual renal function in boys with posterior urethral valves. In a significant proportion of patients with normal renal function the initial renal ultrasound study revealed echogenic kidneys, although only a small proportion with poor renal function had normal kidneys.