Z-scores of fetal bladder size for antenatal differential diagnosis between posterior urethral valves and urethral atresia

OBJECTIVE

To construct reference values for fetal urinary bladder distension in pregnancy and use Z-scores as a diagnostic tool to differentiate posterior urethral valves (PUV) from urethral atresia (UA).

METHODS

This was a prospective cross-sectional study in healthy singleton pregnancies aimed at constructing nomograms of fetal urinary bladder diameter and volume between 15 and 35 weeks' gestation. Z-scores of longitudinal bladder diameter (LBD) were calculated and validated in a cohort of fetuses with megacystis with ascertained postnatal or postmortem diagnosis, collected from a retrospective, multicenter study. Correlations between anatomopathological findings, based on medical examination of the infant or postmortem examination, and fetal megacystis were established. The accuracy of the Z-scores was evaluated by receiver-operating-characteristics (ROC)-curve analysis.

RESULTS

Nomograms of fetal urinary bladder diameter and volume were produced from three-dimensional ultrasound volumes in 225 pregnant women between 15 and 35 weeks of gestation. A total of 1238 urinary bladder measurements were obtained. Z-scores, derived from the fetal nomograms, were calculated in 106 cases with suspected lower urinary tract obstruction (LUTO), including 76 (72%) cases with PUV, 22 (21%) cases with UA, four (4%) cases with urethral stenosis and four (4%) cases with megacystis-microcolon-intestinal hypoperistalsis syndrome. Fetuses with PUV showed a significantly lower LBD Z-score compared to those with UA (3.95 vs 8.83, P < 0.01). On ROC-curve analysis, we identified 5.2 as the optimal Z-score cut-off to differentiate fetuses with PUV from the rest of the study population (area under the curve, 0.84 (95% CI, 0.748-0.936); P < 0.01; sensitivity, 74%; specificity, 86%).

CONCLUSIONS

Z-scores of LBD can distinguish reliably fetuses with LUTO caused by PUV from those with other subtypes of LUTO, with an optimal cut-off of 5.2. This information should be useful for prenatal counseling and management of LUTO. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Altered sacral neural crest development in Pax3 spina bifida mutants underlies deficits of bladder innervation and function

Mouse models of Spina bifida (SB) have been instrumental for identifying genes, developmental processes, and environmental factors that influence neurulation and neural tube closure. Beyond the prominent neural tube defects, other aspects of the nervous system can be affected in SB with significant changes in essential bodily functions such as urination. SB patients frequently experience bladder dysfunction and SB fetuses exhibit reduced density of bladder nerves and smooth muscle although the developmental origins of these deficits have not been determined. The Pax3 Splotch-delayed (Pax3^Sp-d) mouse model of SB is one of a very few mouse SB models that survives to late stages of gestation. Through analysis of Pax3^Sp-d mutants we sought to define how altered bladder innervation in SB might arise by tracing sacral neural crest (NC) development, pelvic ganglia neuronal differentiation, and assessing bladder nerve fiber density. In Pax3^Sp-d/Sp-d fetal mice we observed delayed migration of Sox10+ NC-derived progenitors (NCPs), deficient pelvic ganglia neurogenesis, and reduced density of bladder wall innervation. We further combined NC-specific deletion of Pax3 with the constitutive Pax3^Sp-d allele in an effort to generate viable Pax3 mutants to examine later stages of bladder innervation and postnatal bladder function. Neural crest specific deletion of a Pax3 flox allele, using a Sox10-cre driver, in combination with a constitutive Pax3^Sp-d mutation produced postnatal viable offspring that exhibited altered bladder function as well as reduced bladder wall innervation and altered connectivity between accessory ganglia at the bladder neck. Combined, the results show that Pax3 plays critical roles within sacral NC that are essential for initiation of neurogenesis and differentiation of autonomic neurons within pelvic ganglia.

Perfluoropolyether carboxylic acids (novel alternatives to PFOA) impair zebrafish posterior swim bladder development via thyroid hormone disruption

Perfluoropolyether carboxylic acids (PFECAs, CF₃(OCF₂)_nCOO^-, n = 2-5) are novel alternatives to perfluorooctanoic acid (PFOA) and are widely used in industrial production. However, although they have been detected in surface water and human blood, their toxicities on aquatic organisms remain unknown. We used zebrafish embryos to compare the developmental toxicities of various PFECAs (e.g., perfluoro (3,5,7-trioxaoctanoic) acid (PFO3OA), perfluoro (3,5,7,9-tetraoxadecanoic) acid (PFO4DA), and perfluoro (3,5,7,9,11-pentaoxadodecanoic) acid (PFO5DoDA)) with that of PFOA and to further reveal the key events related to toxicity caused by these chemicals. Results showed that, based on half maximal effective concentrations (EC₅₀), toxicity increased in the order: PFO5DoDA > PFO4DA > PFOA > PFO3OA, with uninflated posterior swim bladders the most frequently observed malformation. Similar to PFOA, PFECA exposure significantly lowered thyroid hormone (TH) levels (e.g., T3 (3,5,3'-L-triiodothyronine) and T4 (L-thyroxine)) in the whole body of larvae at 5 d post-fertilization following disrupted TH metabolism. In addition, the transcription of UDP glucuronosyltransferase 1 family a, b (ugt1ab), a gene related to TH metabolism, increased dose-dependently. Exogeneous T3 or T4 supplementation partly rescued PFECA-induced posterior swim bladder malformation. Our results further suggested that PFECAs primarily damaged the swim bladder mesothelium during early development. This study is the first to report on novel emerging PFECAs as thyroid disruptors causing swim bladder malformation. Furthermore, given that PFECA toxicity increased with backbone OCF₂ moieties, they may not be safer alternatives to PFOA.

Characterization of Histone Deacetylase Expression Within In Vitro and In Vivo Bladder Cancer Model Systems

Epigenetic aberrations are prominent in bladder cancer (BC) and contribute to disease pathogenesis. We characterized histone deacetylase (HDAC) expression, a family of deacetylation enzymes, in both in vitro and in vivo BC model systems and analyzed expression data from The Cancer Genome Atlas (TCGA). Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting analysis was used to determine the expression status of Class I and II HDACs in ten human BC cell lines, while qRT-PCR was used to determine HDAC expression in 24 human tumor specimens. The TCGA cohort consists of 408 muscle invasive BC (MIBC) clinical samples and analysis of this data set identified expression of HDAC4 and -9 as being associated with basal–squamous disease. These findings agree with qRT-PCR results identifying increased expression of HDAC4, -7, and -9 in basal BC cell lines (p < 0.05; Kruskal–Wallis test) and in clinical specimens with invasive bladder cancer (not statistically significant). We also observed increased expression in Hdac4, -7, and -9 in commonly used BC mouse models. Here, we identify suitable preclinical model systems for the study of HDACs, and show increased expression of Class IIa HDACs, specifically HDAC4 and HDAC9, in basal BC cell lines and in invasive clinical specimens. These results suggest this class of HDACs may be best suited for targeted inhibition in patients with basal BC.

Antenatal staging of congenital lower urinary tract obstruction

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Loss of smooth muscle myosin heavy chain results in the bladder and stomach developing lesion during foetal development in mice

Smooth muscle myosin heavy chain (SM-MHC) is exclusively expresses in smooth muscle, which takes part in smooth muscle cell contraction. Here, we used an insertional mutation mouse whose heavy polypeptide 11 (Myh11) gene has been disrupted and no SM-MHC protein has been detected. Compared to the wild-type and SM-MHC^+/- mice, the SM-MHC^-/- neonates had large round bellies, thin-walled giant bladders, and large stomachs with huge gas bubbles. Most of it died within 10 h and the rest within 20 h after birth. Further analysis of the developing foetuses from 16.5 days postcoitum (dpc) stage to newborn showed no significant (P<0.05) difference in the ratio of Mendelian inheritance and average body weight among SM-MHC^+/+ , SM-MHC^+/- and SM-MHC^-/- mice, whereas the abnormal exterior appearance was observed in each SM-MHC^-/- bladders from 16.5 dpc. Histological analysis showed no difference in stomach tissues but evidently thin-walled smooth muscle layer and a giant cavity in bladders of SM-MHC^-/- foetuses at various stages from 15.5 dpc to newborn. The results indicated that the defect of SM-MHC lead to the bladder developing lesions initially at 15.5 dpc stage in mouse and also implied that the SM-MHC loss might result in the gas bubbles in stomach. The study should facilitate further detailed analyses of the potential role of SM-MHC in bladder and stomach development.

Diagnosis of fetal megacystis with chromosomal abnormality by 2D prenatal ultrasound: A case report

RATIONALE

The pathogenesis of fetal megacystis is divided into obstructive and nonobstructive. Megacystis combined with chromosomal abnormalities is rare and most of the cases are nonobstructive.

PATIENT CONCERNS

The fetus showed posterior urethral obstructive megacystis with features of bladder enlargement, "keyhole" feature, and thick bladder wall.

DIAGNOSES

Here, we present a case of fetal megacystis diagnosed by ultrasound at pregnancy week 15+2 and with multisystem abnormalities.

OUTCOMES

Moreover, the fetus showed edema, umbilical cord cyst, cardiac dysplasia, hook-shaped hand, and strephenopodia. These abnormalities strongly suggested chromosomal abnormalities. The fetus was diagnosed with trisomy 18 by amniocentesis. Posterior urethral obstructive megacystis was confirmed by pathology.

LESSONS

In conclusion, this case suggests that in the presence of fetal megacystis and multisystem abnormalities, causes should be investigated and the possibility of chromosomal abnormalities should be considered in the presence of multisystem developmental abnormalities.

Fetal megacystis: prediction of spontaneous resolution and outcome

OBJECTIVES

To investigate the natural history of fetal megacystis from diagnosis in utero to postnatal outcome, and to identify prognostic indicators of spontaneous resolution and postnatal outcome after resolution.

METHODS

This was a national retrospective cohort study. Fetal megacystis was defined in the first trimester as a longitudinal bladder diameter (LBD) ≥ 7 mm, and in the second and third trimesters as an enlarged bladder failing to empty during the entire extended ultrasound examination. LBD and gestational age (GA) at resolution were investigated with respect to likelihood of resolution and postnatal outcome, respectively. Sensitivity, specificity and area under the receiver-operating characteristics curve (AUC) were calculated.

RESULTS

In total, 284 cases of fetal megacystis (93 early megacystis, identified before the 18^th week, and 191 late megacystis, identified at or after the 18^th week) were available for analysis. Spontaneous resolution occurred before birth in 58 (20%) cases. In cases with early megacystis, LBD was predictive of the likelihood of spontaneous resolution (sensitivity, 80%; specificity, 79%; AUC, 0.84), and, in the whole population, GA at regression was predictive of postnatal outcome, with an optimal cut-off at 23 weeks (sensitivity, 100%; specificity, 82%; AUC, 0.91). In the group with early megacystis, the outcome was invariably good when resolution occurred before the 23^rd week of gestation, whereas urological sequelae requiring postnatal surgery were diagnosed in 3/8 (38%) cases with resolution after 23 weeks. In the group with late megacystis, spontaneous resolution was associated with urological complications after birth, ranging from mild postnatal hydronephrosis in infants with resolution before 23 weeks, to more severe urological anomalies requiring postnatal surgery in those with resolution later in pregnancy. This supports the hypothesis that an early resolution of megacystis is often related to a paraphysiological bladder enlargement that resolves early in pregnancy without consequences, while antenatal resolution occurring later in pregnancy (after the 23^rd week of gestation) should suggest a pathological condition with urological sequelae.

CONCLUSIONS

In fetal megacystis, LBD and GA at regression can be used as predictors of resolution and outcome, respectively. These parameters could help in fine-tuning the prognosis and optimizing the frequency of follow-up scans. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

[PATHOGENICALLY INDUCED APOPTOSIS CAUSED BY HYPOXIC EFFECTS IN THE URINARY SYSTEM ORGANS OF FETUSES AND NEWBORNS (EXPERIMENTAL STUDY)]

The purpose of the study was to identify the characteristics of apoptosis in the kidneys, ureters and bladder of fetuses and newborns in the modeling of chronic intrauterine hypoxia, acute postnatal hypoxia and mixed hypoxia. An experiment was conducted on WAG rats for modeling high altitude hypoxia. Experimental animals were divided into four groups: I - control - fetuses and newborns from healthy rats; II - modeling of chronic intrauterine hypoxia; III - modeling of acute postnatal hypoxia; IV - modeling of mixed hypoxia. The material of the study was the tissue of the kidneys, ureters and bladder of fetuses and newborns. In group I in the kidneys of fetuses the mean value of the number of p53-positive cells was 7.83±0.31, newborns - 5.40±0.28; in the ureters and bladder of fetuses - 5.77±0.29 and 6.97±0.32, newborns - 3.58±0.21 and 5.36±0.28. In the kidneys in group II the mean value of the number of p53-expressing cells in fetuses was 1.43±0.50, in newborns - 21.72±0.58; in group III in newborns - 15.03±0.63; in group IV in newborns - 33.33±0.72. The mean value of the number of p53-expressing cells in the ureters and bladder in group II in fetuses was 13.17±0.49 and 11.83±0.43, in newborns - 16.24±0.37 and 15.38±0.37; in group III in newborns - 7.25±0.27 and 8.68±0.32; in group IV in newborns - 19.63±0.31and 21.03±0.40. As the result of the study it was found that experimental hypoxia induced apoptotic processes in the kidneys, ureters and bladder of fetuses and newborns, the severity of which was moderate in the modeling of acute postnatal hypoxia, expressed in the modeling of chronic intrauterine hypoxia and strongly expressed in the modeling of mixed hypoxia. Under the influence of acute postnatal hypoxia, chronic intrauterine hypoxia and mixed hypoxia in the ureters and bladder of fetuses and newborns p53-positive cells were located evenly in all layers of the wall of these organs, whereas in the kidneys p53-positive cells prevailed in the tubular component. In the modeling of chronic intrauterine hypoxia apoptotic processes in the kidneys, ureters and bladder increased in newborns in comparison with fetuses.

Fetal stomach and gallbladder in contact with the bladder wall is a common ultrasound sign of stomach-down left congenital diaphragmatic hernia

PURPOSE

The aim of this study was to identify sonographic (US) findings that can assist in prenatal diagnosis of stomach-down left congenital diaphragmatic hernia (CDH), specifically related to positioning of the abdominal contents including the stomach, bladder, and gallbladder.

METHODS

All US examinations with a postnatally confirmed diagnosis of stomach-down left CDH over a 13-year period were retrospectively reviewed for abnormal position of the abdominal contents, including whether the fetal stomach was in contact with the urinary bladder. Normal fetuses that underwent comprehensive US surveys were similarly evaluated for comparison in a 2:1 ratio.

RESULTS

Twenty-two fetuses with stomach-down left CDH were identified in a cohort of 278 fetuses with left CDH. In 15/22 (68.2%) cases of stomach-down left CDH, the bladder and stomach walls were in contact. Contact of the fetal gallbladder with the fetal bladder wall was also observed and was present even more commonly (17/22 cases [77.3%]). There was no case of either the stomach or gallbladder in contact with the bladder wall in the normal fetal cohort (n = 44).

CONCLUSIONS

Recognition of the fetal stomach and/or gallbladder in contact with the bladder wall can help in the detection of stomach-down left CDH. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:8-13, 2017.

Morphology of the fetal bladder during the second trimester: comparing genders

OBJECTIVES

The aim of the present study was to determine, by histological and stereological analysis, whether there are between-gender structural differences in the bladder in the second gestational trimester in human fetuses.

MATERIAL AND METHODS

Forty bladders, which were obtained from 40 human fetuses (20 males and 20 females) ranging in age from 13 to 23 weeks post-conception (WPC), were studied. The fetuses were macroscopically well preserved, without anomalies of the urinary and genital systems; the cases with syndromes were abandoned. The bladders were dissected and embedded in paraffin, from which 5-μm thick sections were obtained and stained with: Masson's trichrome, to quantify connective and smooth muscle tissue; Weigert's resorcin fuchsin, to observe elastic fibers; picrosirius red with polarization, to observe collagen; and anti-beta III tubulin antibody, to observe the bladder nerves. The images were captured with an Olympus BX51 microscope and Olympus DP70 camera. The stereological analysis was performed with the Image Pro and Image J programs, using a grid to determine volumetric densities (Vv). Means were statistically compared using simple linear regression and the paired t-test (P<0.05).

RESULTS

The fetuses weighed between 60 and 490 g, and had crown-rump lengths between 9.5 and 20.4 cm. No elastic system fibers were observed in any bladders. Quantitative analysis indicated no differences in the Vv of the smooth muscle cells in the male bladders (26.19-50.16%; mean=35.66%) compared to the female ones (30.60-45.63%; mean=38.73%) (P=0.740) and there were also no differences in the Vv of the connective tissue in females (40.52-60.40%; mean=50.69%) and males (38.84-70.16%; mean=57.04%) (P=0.0506). There were no differences observed in the distribution of the nerves and collagen between the genders.

CONCLUSION

The histological analysis of the smooth muscle, collagen, nerves and connective tissue of the developing bladders revealed that there are no gender differences during weeks 13-23 of gestation.

Gender-related fetal development of the internal urethral sphincter

OBJECTIVE

To investigate the fetal development of the internal urethral sphincter and the gender-related morphologic differences of the bladder outlet.

MATERIALS AND METHODS

Thirty-seven (14 female, 23 male) fetal bladder neck specimens (mean gestational age, 19.4 weeks) with the smooth muscle complex of the internal sphincter were investigated histologically. After immunostaining serial sections in 3 reference planes (sagittal, frontal, and horizontal) of the bladder neck, the internal sphincter volumes and bladder outlet diameters were measured and correlated with gender and age of gestation.

RESULTS

Between the 18th and 40th week of gestation, an exponential growth of the internal sphincter muscle with significant higher volumes could be observed in male fetuses compared with female fetuses (internal sphincter volumes, P = .006; radius of the sphincter complex, P = .001). As a result of this gender difference, the bladder outlet was significantly (P = .001) narrower in male than in female fetuses. Moreover, we found a significant positive correlation between age and all measured parameters in both male and female specimens.

CONCLUSION

The present study indicates a significant closer bladder outlet in male fetuses compared than in females. It thereby provides evidence of a gender-related functional obstruction in addition to a suppositious transient infravesical obstruction in male human fetuses.

Development of an animal model to study congenital urinary obstruction

PURPOSE

We outline the development of a reliable model of obstructive uropathy in fetal lambs highlighting our understanding of the critical time points for interventions and the variability of any such model. We identify some discoveries that may have clinical implications.

METHODS

The model requires 60-day-gestation fetal lambs. In lambs, glomerulogenesis is complete by 90 days gestation. (Term is 145 days.) The ability to develop a reliable method of creating bladder outlet obstruction in females, ligating both the urethra and urachus was critical. The lambs are bred to an accuracy of ±24 h.

RESULTS

Creating the model at 50-60 days gestation, produces different expressions of renal dysplasia in groups of lambs undergoing identical interventions at the same stage of gestation. Early complete urethral obstruction can produce the Potter phenotype. An appropriately timed vesico-amniotic shunt preserves renal development, producing a shrunken, non-compliant bladder. Shunting the normal fetal bladder at 80 days gestation produces a similar bladder. Provision of a low-pressure valve in the shunt preserves bladder development and compliance. Using a high-pressure shunt produces results similar to non-shunted lambs.

DISCUSSION

We developed a reliable animal model for obstructive uropathy. Being alert to peripheral results can lead to new findings.

Spatio-temporal distribution of Smads and role of Smads/TGF-β/BMP-4 in the regulation of mouse bladder organogenesis

Although Shh, TGF-β and BMP-4 regulate radial patterning of the bladder mesenchyme and smooth muscle differentiation, it is not known what transcription factors, local environmental cues or signaling cascades mediate bladder smooth muscle differentiation. We investigated the expression patterns of signaling mediated by Smad2 and Smad3 in the mouse embryonic bladder from E12.5 to E16.5 by using qRT-PCR, in situ hybridization and antibodies specifically recognizing individual Smad proteins. The role of Smad2 and Smad3 during smooth muscle formation was examined by disrupting the Smad2/3 signaling pathway using TβR1 inhibitor SB-431542 in organ culture system. qRT-PCR results showed that R-Smads, Co-Smad and I-Smads were all expressed during bladder development. RNA ISH for BMP-4 and immunostaining of TGF-β1 showed that BMP-4 and TGF-β1 were expressed in the transitional epithelium, lamina propia and muscularis mucosa. Smad1, Smad5 and Smad8 were first expressed in the bladder epithelium and continued to be expressed in the transitional epithelium, muscularis mesenchyme and lamina propia as the bladder developed. Smad2, Smad3 and Smad4 were first detected in the bladder epithelium and subsequently were expressed in the muscularis mesenchyme and lamina propia. Smad6 and Smad7 showed overlapping expression with R-Smads, which are critical for bladder development. In bladder explants (E12.5 to E16.5) culture, Smad2 and Smad3 were found localized within the nuclei, suggesting critical transcriptional regulatory effects during bladder development. E12.5 to E16.5 bladders were cultured with and without TβR1 inhibitor SB-431542 and assessed by qRT-PCR and immunofluorescence. After three days in culture in SB-431542, α-SMA, Smad2 and Smad3 expressions were significantly decreased compared with controls, however, with no significant changes in the expression of smooth muscle myosin heavy chain (SM-Myh. Based on the Smad expression patterns, we suggest that individual or combinations of Smads may be necessary during mouse bladder organogenesis and may be critical mediators for bladder smooth muscle differentiation.

Deletion of fibroblast growth factor receptor 2 from the peri-wolffian duct stroma leads to ureteric induction abnormalities and vesicoureteral reflux

Purpose

Pax3cre-mediated deletion of fibroblast growth factor receptor 2 (Fgfr2) broadly in renal and urinary tract mesenchyme led to ureteric bud (UB) induction defects and vesicoureteral reflux (VUR), although the mechanisms were unclear. Here, we investigated whether Fgfr2 acts specifically in peri-Wolffian duct stroma (ST) to regulate UB induction and development of VUR and the mechanisms of Fgfr2 activity.

Methods

We conditionally deleted Fgfr2 in ST (Fgfr2^ST−/−) using Tbx18cre mice. To look for ureteric bud induction defects in young embryos, we assessed length and apoptosis of common nephric ducts (CNDs). We performed 3D reconstructions and histological analyses of urinary tracts of embryos and postnatal mice and cystograms in postnatal mice to test for VUR. We performed in situ hybridization and real-time PCR in young embryos to determine mechanisms underlying UB induction defects.

Results

We confirmed that Fgfr2 is expressed in ST and that Fgfr2 was efficiently deleted in this tissue in Fgfr2^ST−/− mice at embryonic day (E) 10.5. E11.5 Fgfr2^ST−/− mice had randomized UB induction sites with approximately 1/3 arising too high and 1/3 too low from the Wolffian duct; however, apoptosis was unaltered in E12.5 mutant CNDs. While ureters were histologically normal, E15.5 Fgfr2^ST−/− mice exhibit improper ureteral insertion sites into the bladder, consistent with the ureteric induction defects. While ureter and bladder histology appeared normal, postnatal day (P) 1 mutants had high rates of VUR versus controls (75% versus 3%, p = 0.001) and occasionally other defects including renal hypoplasia and duplex systems. P1 mutant mice also had improper ureteral bladder insertion sites and shortened intravesicular tunnel lengths that correlated with VUR. E10.5 Fgfr2^ST−/− mice had decreases in Bmp4 mRNA in stromal tissues, suggesting a mechanism underlying the ureteric induction and VUR phenotypes.

Conclusion

Mutations in FGFR2 could possibly cause VUR in humans.

Analysis of the Sonic Hedgehog signaling pathway in normal and abnormal bladder development

In this study, we examined the expression of Sonic Hedgehog, Patched, Gli1, Gli2, Gli3 and Myocardin in the developing bladders of male and female normal and megabladder (mgb-/-) mutant mice at embryonic days 12 through 16 by in situ hybridization. This analysis indicated that each member of the Sonic Hedgehog signaling pathway as well as Myocardin displayed distinct temporal and spatial patterns of expression during normal bladder development. In contrast, mgb-/- bladders showed both temporal and spatial changes in the expression of Patched, Gli1 and Gli3 as well as a complete lack of Myocardin expression. These changes occurred primarily in the outer mesenchyme of developing mgb-/- bladders consistent with the development of an amuscular bladder phenotype in these animals. These results provide the first comprehensive analysis of the Sonic Hedgehog signaling pathway during normal bladder development and provide strong evidence that this key signaling cascade is critical in establishing radial patterning in the developing bladder. In addition, the lack of detrusor smooth muscle development observed in mgb-/- mice is associated with bladder-specific temporospatial changes in Sonic Hedgehog signaling coupled with a lack of Myocardin expression that appears to result in altered patterning of the outer mesenchyme and poor initiation and differentiation of smooth muscle cells within this region of the developing bladder.

Organotypic culture of the urogenital tract

Organotypic culture is an invaluable technique that allows researchers with the tool to analyze a tissue development in an isolated and well-defined environment. This technique also permits one to study the roles of different signaling systems/signaling molecules and to take advantage of the modern real-time imaging techniques, including confocal microscopy. With great success, our lab has used organotypic culture of the urogenital tract (UGT) to study growth and extension of the mesonephric (Wolffian) duct and its cloaca connection, ureter maturation, and bladder urothelium development (Batourina et al. Nat Genet 32:109, 2002; Batourina et al. Nat Genet 37:1082, 2005; Mendelsohn Organogenesis 5:306, 2009).

Effectiveness of fetal cystoscopy as a diagnostic and therapeutic intervention for lower urinary tract obstruction: a systematic review

OBJECTIVE

To determine the effectiveness of fetal cystoscopy in the prenatal diagnosis of and intervention for congenital lower urinary tract obstruction.

METHODS

This study was a literature search using MEDLINE, Embase, Cochrane Library, MEDION, Web of Science reference lists and contact with experts. All studies reporting on fetal cystoscopy in lower urinary tract obstruction with data for a 2 × 2 table were selected for review. No language restrictions were applied. There was independent selection of studies, data extraction and quality assessment by two reviewers. Peto odds ratios were calculated as a summary measure of effect.

RESULTS

A total of 2071 citations were identified and 66 papers selected for detailed evaluation, from which four papers with a total of 63 patients were selected for inclusion. Two papers had results for the use of cystoscopy in diagnosis, showing that fetal cystoscopy altered the ultrasound diagnosis of the underlying pathology in 36.4 and 25.0% of fetuses, respectively. Compared to no treatment, fetal cystoscopic intervention demonstrated an odds ratio for improved perinatal survival of 20.51 (95% CI, 3.87-108.69). However, comparing vesicoamniotic shunt (VAS) with fetal cystoscopy there appeared to be no significant improvement in the perinatal survival odds ratio of 1.49 (95% CI, 0.13-16.97). These results had wide CIs and for cystoscopy vs. VAS, all results crossed the line of no effect.

CONCLUSION

There is little published evidence for the effectiveness of therapeutic fetal cystoscopy as an intervention for congenital lower urinary tract obstruction and the quality of this evidence is poor. It should thus be considered to be an 'experimental intervention' and subjected to further investigation.

Early fetal cystoscopy for first-trimester severe megacystis

OBJECTIVES

To report the feasibility of early fetal cystoscopy for the prenatal diagnosis and therapy of severe first-trimester megacystis.

METHODS

Between January 2008 and February 2010, early fetal cystoscopy at 16 weeks of gestation was offered to 15 patients whose fetuses presented with severe first-trimester megacystis. All infants were followed up for 6-12 months after birth. Autopsy was always performed whenever fetal or neonatal deaths occurred.

RESULTS

Seven patients decided to undergo fetal therapy, and eight elected to continue with expectant observation. One fetus died before early fetal cystoscopy was performed. Therefore, six fetuses underwent early fetal cystoscopy. Urethral atresia was diagnosed in three fetuses during fetal cystoscopy and confirmed at autopsy following termination of pregnancy at 19-20 weeks in all cases. Posterior urethral valves were diagnosed and successfully fulgurated by laser during early cystoscopy in three fetuses, two of which survived with normal renal and bladder function after birth; the remaining fetus had a postnatal diagnosis of megacystis-microcolon intestinal hypoperistalsis syndrome and died neonatally. In the expectantly managed group, no survivals were observed, even among cases with 'isolated' posterior urethral valves.

CONCLUSIONS

Percutaneous early fetal cystoscopy is feasible for prenatal diagnosis and therapy of severe megacystis.

Fetal cardiovascular effects of lower urinary tract obstruction with giant bladder

OBJECTIVE

Lower urinary tract obstruction (LUTO) with massive bladder distension impacts on a variety of developing organ systems with consequent morbidity and mortality. The impact of LUTO on the fetal cardiovascular system has not previously been investigated. We hypothesize that a giant, distended bladder within the pelvis may cause vascular compression with observable consequences.

METHODS

Fetal echocardiography was performed in 42 fetuses with LUTO and compared with 35 normal controls matched for gestational age. Parameters investigated included cardiothoracic ratio, presence or absence of ventricular hypertrophy and pericardial effusion. Doppler echocardiographic examination of mitral and tricuspid valve inflow and the ductus venosus was performed. To assess arterial vascular impedance, pulsatility indices (PIs) were calculated for segments of the descending aorta and right and left iliac arteries (RIA and LIA).

RESULTS

In the LUTO group an increased cardiothoracic ratio was seen in nine (21%), ventricular hypertrophy in 12 (29%) and small pericardial effusion in 15 (36%). Filling characteristics of the right ventricle in the LUTO group demonstrated greater dependency upon atrial contraction, and ductus venosus flow demonstrated higher downstream impedance to filling, than in controls, suggesting altered compliance. The LUTO group also had lower distal descending aorta PI (1.53 ± 0.38 vs. 1.76 ± 0.44, P = 0.04), lower RIA-PI (1.31 ± 0.29 vs. 1.76 ± 0.44, P < 0.001) and lower LIA-PI (1.41 ± 0.44 vs. 1.73 ± 0.31, P < 0.01) than controls, suggesting vascular compression and increased impedance to flow.

CONCLUSIONS

LUTO with giant urinary bladder compresses the iliac arteries, which may lead to increased afterload. Further study is warranted to examine the impact of fetal treatment such as bladder drainage on these cardiovascular parameters.

Measurement of fetal urine production to differentiate causes of increased amniotic fluid volume

OBJECTIVES

In polyhydramnios, amniotic fluid (AF) volume can be increased not only as a result of increased fetal urine production, but also due to several other factors, including impairment of both fetal swallowing and gastrointestinal (GI) absorption of AF. Our aim was to evaluate whether measurement of the fetal urine production rate (UPR) can be used to differentiate the causes of increased AF volume.

METHODS

This cross-sectional study included 54 pregnant women with an increased amniotic fluid index (AFI), defined as AFI > or = 18 cm, divided into two groups according to the presence of fetal anomalies that are associated with impairment of fetal swallowing or decreased GI absorption of AF (Group 1, n = 14) or the absence of fetal anomalies (Group 2, n = 40). The control group included 96 normal pregnancies with normal AFI (8 < or = AFI < 18 cm) (Group 3). Fetal UPR was obtained by serial bladder volume measurements (two to four times, with a median interval of 5 min between each) using the rotational method of Virtual Organ Computer-aided AnaLysis (VOCAL()) with three-dimensional ultrasound. To adjust for fetal weight (Wt) and gestational age (GA), UPR_Wt and UPR_SD were calculated using the following formulae: UPR_Wt = measured UPR/estimated fetal weight and UPR_SD = (measured UPR - mean UPR for each GA)/SD of UPR for each GA.

RESULTS

The AFI was increased significantly in Groups 1 and 2 compared with Group 3. However, the median fetal UPR in Group 1 did not differ from that of Group 3, in contrast to the higher median fetal UPR in Group 2 compared with Groups 1 and 3; this difference remained significant after adjusting for GA and estimated fetal weight in terms of UPR_SD and UPR_Wt. In Groups 2 and 3, AFI and UPR had a positive correlation in terms of UPR, UPR_SD and UPR_Wt.

CONCLUSIONS

Our findings that fetal UPR is significantly increased in cases with increased AFI without fetal anomalies, but not in those with increased AFI and fetal anomalies involving decreased GI absorption of AF, might be used to differentiate causes of increased AF volume. In the absence of fetal anomalies, AFI and fetal UPR correlate positively.

Vascular endothelial growth factor and bladder from a different perspective: not only an angiogenic factor

Angiogenesis has a key role for embryonic development and is crucial in several major diseases. Molecular basis of angiogenesis has been widely investigated (J Biochem Mol Biol. 2006;39:469-478, Oncogene. 2000;19:5598-5605). In this review, vascular endothelial growth factor (VEGF) and related receptors and their key roles in embryonic bladder development are discussed. The normal VEGF expression and related angiogenesis pattern of embryonic bladder are highlighted. The VEGF family especially VEGF-A is the major player in angiogenesis as well as many other angiogenic factors and activates 2 tyrosine kinase receptors, VEGFR-1 and VEGFR-2 (J Biochem Mol Biol. 2006;39:469-478). Besides its worthy role in angiogenesis, VEGF-A also seems to participate in normal bladder development (J Urol. 2007;177:1552-1557, Br J Urol Int. 2006;98:217-225). In previous studies, we have shown that exogenous VEGF or hypoxia-induced endogenous upregulation of this protein accelerates the growth of the bladder by detrusor and urothelium hypertrophy and hyperplasia (J Urol. 2007;177:1552-1557, Br J Urol Int. 2006;98:217-225, Dev Biol. 1997;183:139-149, Neurourol Urodyn. 2004;23:342-348). This abrupt role of VEGF on detrusor muscle through a hypoxic pathway may potentially be a part of the solution for many urologic conditions such as remodeling of detrusor muscle in antenatal bladder outlet obstruction.

Derivations that enable the testing of fetal urine production as a method of fetal surveillance

Purpose

To calculate the measurement error of the hourly fetal urine production rate (HFUPR) and evaluate the implication of different methods for measuring the HFUPR, i.e. ellipsoid versus sum-of-cylinders method.

Methods

The calculation was based on sonographic documentation of the increased bladder volumes during the filling phase, the bladder volume measurement error and the number and time points of bladder image capture.

Results

The probability of a false pathological reading was excluded (0%) with the sum-of-cylinders method for gestational ages of ≥30 weeks. With the ellipsoid method, the risk was higher. The maximum changes which could be exclusively explained by measurement error were four to five times greater with the ellipsoid method compared with the sum-of-cylinders method.

Conclusions

The present paper illustrates a careful evaluation of the HFUPR measurement error and the implications of using different ultrasound methods for bladder volume estimations.

Electronic supplementary material

The online version of this article (doi:10.1007/s00404-009-1242-6) contains supplementary material, which is available to authorized users.

Keyhole sign: how specific is it for the diagnosis of posterior urethral valves?

OBJECTIVES

Posterior urethral valves (PUV) are the most common cause of renal impairment in boys during early childhood. Although antenatal suspicion of this pathology has become quite common in recent years, prenatal diagnosis remains challenging. The aim of this study was to evaluate the predictive value of different ultrasound criteria currently used to diagnose PUV.

METHODS

We reviewed the antenatal and postnatal files of 54 male patients referred to our center from 2000 to 2006 after detection of fetal bilateral hydronephrosis. The following ultrasound criteria were evaluated in relation to the postnatal diagnosis of PUV: amniotic fluid volume, bladder wall thickness, bladder dilatation and the presence of the 'keyhole sign'.

RESULTS

Forty-two fetuses (77.8%) were suspected to have PUV on prenatal examination. Out of these, 29 (69.0%) had PUV confirmed postnatally. The sensitivity and specificity of the antenatal diagnosis of PUV were 94% and 43%, respectively. Increased bladder wall thickness and bladder dilatation were highly associated with the diagnosis of PUV (P < 0.001). However, a thick-walled bladder was observed in 39.1% and a dilated bladder in 47.8% of the infants with a postnatal diagnosis other than PUV. The presence of the keyhole sign was not found to predict a diagnosis of PUV (P = 0.27).

CONCLUSION

In this series the use of classical prenatal ultrasound signs to diagnose PUV showed high sensitivity but low specificity. The best diagnostic indicators were increased bladder wall thickness and dilatation of the bladder. The keyhole sign was not found to be a reliable predictor of PUV.

Late second trimester assessment of pyelectasis (SERP) to predict pediatric urological outcome is improved by checking additional features

OBJECTIVE

Counseling for pyelectasis in the late 2nd trimester is usually based only upon assessing the antero-posterior (AP) width of the renal pelvis. We hypothesized that checking additional features would better predict postnatal outcome.

STUDY DESIGN

Ultrasound (<24 weeks gestational age (GA)) and newborn outcome data collected prospectively since 1986 were analyzed retrospectively. We determined if outcome predictions in kidneys with a sonographically evident renal pelvis (SERP), which had evaluation of additional features (e.g., renal and bladder lengths, presence of a dilated ureter or dilated calyces) are more accurate than those that did not have these features.

RESULTS

There were 286 fetuses studied with pediatric follow-up of an average of 6.5 years. There were 338 exams providing 459 ultrasound images with SERP. Additional features were not assessed in 183 fetuses; however 103 fetuses did have evaluation of additional features. These features were categorized as abnormal (92) or as normal (11). Fetuses with SERP and abnormal additional features required extensive urological care or died 6.1 times more often than fetuses in which additional features were not examined (p < 0.001) and 12.9 times more often when additional features were normal (p < 0.001).

CONCLUSION

Fetal kidneys with SERP (<24 weeks GA) and an abnormal additional ultrasound feature had extensive pediatric care significantly more often than when such features were not evaluated or were normal.

Hydronephrosis index: a better physiological reference in antenatal ultrasound for assessment of fetal hydronephrosis

OBJECTIVE

To establish a nomogram of fetal hydronephrosis index (HI) (anteroposterior diameter of renal pelvis divided by urinary bladder volume) at different gestational ages, to serve as a new reference for antenatal ultrasound examination, and to avoid overestimation of fetal hydronephrosis due to transient effect of a distended fetal bladder.

STUDY DESIGN

504 uncomplicated singleton pregnancies from 20 to 38 weeks' gestation were included. In each fetus, the maximum anteroposterior diameters of both renal pelves were measured on transverse view of fetal kidneys. Urinary bladder volume was calculated using the ovoid volume formula. HI was derived accordingly.

RESULTS

Values of HI vary significantly at different trimesters of pregnancy. HI was much higher (mean = 0.1543) from 20 to 27 weeks' gestation, and its value decreased significantly (mean = 0.0253) from 28 to 38 weeks' gestation (P < .05, independent-sample t test). As gestational age increased, HI decreased (R(2) = 0.5921).

CONCLUSIONS

HI is easy to be measured and can be used as a new physiological reference for assessment of fetal hydronephrosis by eliminating the confounding effect of a full fetal bladder. The change in values of HI throughout gestation supports the clinical importance of a nomogram for this new index.

Validation of Quintero stage III sub-classification for twin-twin transfusion syndrome based on visibility of donor bladder: characteristic differences in pathophysiology and prognosis

OBJECTIVE

To validate the Quintero stage III subclassification for twin-twin transfusion syndrome (TTTS) based on visibility of the bladder of the donor twin.

METHODS

Between July 2002 and August 2006, there were 131 pregnant Japanese women affected by severe TTTS before 26 weeks' gestation, treated with fetoscopic laser surgery at five centers in Japan, whose pregnancies continued beyond 22 weeks. Outcome data were available in all cases and surviving infants were followed up for at least 6 years. This study focused on the Stage III TTTS patients. These were subclassified into Stage III atypical (abnormal Doppler flow with visible donor bladder) and Stage III classical (abnormal Doppler flow with non-visible donor bladder) groups. Perioperative data and postnatal outcomes were compared between the groups.

RESULTS

Seven Stage I, 22 Stage II, 82 Stage III and 20 Stage IV pregnancies continued beyond 22 weeks. There was a significantly higher incidence of absent or reversed end-diastolic velocity in the umbilical artery (UA-AREDV) of the donor in Stage III atypical than in Stage III classical patients (83.8% vs. 53.3%, P = 0.004). Stage III atypical cases also had a significantly higher incidence of arterioarterial (AA) anastomoses (72.9% vs. 17.8%, P < 0.001) and intrauterine fetal demise (IUFD) of the donor (43.2% vs. 13.3%, P = 0.002). However, there were no differences in overall survival or in abnormal brain scans of surviving infants. Donors with both UA-AREDV and AA anastomoses had a significantly higher incidence of IUFD compared with the others (53.3%, P < 0.001).

CONCLUSIONS

Quintero stage III atypical was characterized by a high incidence of AA anastomoses and UA-AREDV of the donor, resulting in IUFD. Subclassification of Stage III based on visibility of the bladder of the donor twin was adequate for and compatible with differentiating prognosis and pathophysiology.

Erroneous statement regarding 2D ultrasound fetal urinary bladder volume measurement

The aim of the current paper is to inform the readers of an erroneous statement on the standard deviation (SD) when estimating the volume of fetal urinary bladder by 2D ultrasound. In the Archives of Gynecology and Obstetrics 2007; 276 (4), page 345-349, the authors Peixoto-Filho F.M. et al. refer to some studies presented by our group versus other studies regarding volume estimation of the fetal urinary bladder, in particular the ellipsoid method pioneered by Stuart Campbell in 1973 and the sum-of-cylinders method from our group. In our studies the volume estimation method was improved in three steps using methodological modifications. The SD was reduced from 17.3-10.9% to 12.9-5.5%, and 8.8-3.5% (bladder volumes 5-40 mL) The reductions were accompanied by P-values of 0.0270 (1 vs. 2) and 0.0543 (2 vs. 3), respectively. When comparing method 3 vs. 1 the P value was 0.0032. The SD reduction using method 3 vs. 2 did not reach statistical significance, however. Using this lack of significance on the 5% significance level, to prove that there were no improvements at all with our methodological modifications of the 2D ultrasound, as done by the authors, is misleading.

The use of inversion mode and 3D manual segmentation in volume measurement of fetal fluid-filled structures: comparison with Virtual Organ Computer-aided AnaLysis (VOCAL)

OBJECTIVE

Volume measurements by three-dimensional (3D) ultrasonography are considered more accurate than those performed by two-dimensional (2D) ultrasonography. The purpose of this study was to compare the agreement of three techniques, as well as the inter- and intraobserver agreements for volume measurements of fetal fluid-filled structures.

METHODS

Fifty 3D volume datasets of fetal stomachs and bladders were explored. Volume measurements were performed independently by two observers using: (1) Virtual Organ Computer-aided AnaLysis (VOCAL); (2) inversion mode; and (3) 'manual segmentation'. Reliability was evaluated using intraclass correlation coefficient (ICC), and Bland-Altman plots were generated to examine bias and agreement. The time required to complete the measurements was compared using Student's t-test or the Wilcoxon Signed Rank Test, and P-values < 0.025 or < 0.05 were considered statistically significant.

RESULTS

All volume datasets could be measured using the three techniques. A high degree of reliability was observed between: (1) VOCAL and inversion mode (ICC, 0.995; 95% CI, 0.992-0.997); (2) VOCAL and manual segmentation (ICC, 0.997; 95% CI, 0.995-0.998); and (3) inversion mode and manual segmentation (ICC, 0.995; 95% CI, 0.992-0.997). There was good agreement between VOCAL and inversion mode (mean, - 2.4%; 95% limits of agreement, - 20.1 to 15.3%), VOCAL and manual segmentation (mean, - 8.3%; 95% limits of agreement, - 28.8 to 12.2%) as well as between inversion mode and manual segmentation (mean, 5.9%, 95% limits of agreement: - 14.3 to 26%). Manual segmentation and inversion mode measurements were obtained significantly faster than those by VOCAL.

CONCLUSIONS

Volume measurements of fetal fluid-filled structures of relatively regular shape with inversion mode and manual segmentation are feasible. Both techniques have good agreement with VOCAL and are significantly faster than VOCAL. Inversion mode is a reliable method for volume calculations of fluid-filled organs, whereas manual segmentation can be used when volume measurements by VOCAL or inversion mode are technically difficult to obtain, such as solid structures with poorly defined borders as the volume dataset is rotated, like the uterine cervix.

Immunohistochemical study of the pre- and postnatal innervation of the dog lower urinary tract: morphological aspects at the basis of the consolidation of the micturition reflex

Immunohistochemical studies were performed on male and female bladder and urethra collected from 4 adults dogs and 10 foetal specimens with crown-rump length from 53 to 155 mm (medium-sized breeds, presumptive 38 days of gestation to term). A panel of antisera was tested, including PGP 9.5 to describe the general intramural innervation, ChAT and TH to depict the cholinergic and nor-adrenergic components and NOS1, CGRP, SP, NPY, VIP, SOM, GAL, 5-HT to investigate the possible nitrergic, peptidergic and aminergic ones. A rich cholinergic innervation was present in adult bladder and urethra, along with a lesser number of adrenergic nerves and a small number of nitrergic ones. Either bladder or urethra received numerous CGRP-, SP-, NPY-, VIP-containing nerve fibres which were distributed throughout the muscle layers. All over the lower urinary tract strong to weak ChAT-, CGRP-, SP- and NPY-immunoreactivity was detected in intramural ganglia, in peripheral nerve bundles and around blood vessels. 5-HT-immunoreactive endocrine cells were present in the urethral epithelium. Early foetal organs were supplied only by cholinergic nerve fibres. Few NOS-, CGRP- and SP-ergic components appeared at the end of pregnancy. It can be guessed that sensory mediators such as CGRP and SP increase in postnatal ages while other neuropeptides, such as NPY and VIP, appear only after birth, as the urinary reflex consolidates.

Doppler indices in the umbilical arteries: influence of vessel curvature induced by bladder filling

Doppler indices are widely used to assess normal versus pathologic haemodynamics. In obstetrics, the assessment of abnormal values in some critical compartments, such as the umbilical arteries (UA), may be crucial in the clinical management of growth-restricted foetuses. It was recently proposed that the UA should be sampled in their perivesical portion (PVC), i.e., where they surround the foetal urinary bladder. However, measurements at this site could be biased by the degree of curvature of the vessel due to bladder filling. We investigated this possibility in vivo and in vitro, i.e., measurements on rubber tubes at different radii of curvature R(c). There was significant dependence of the Doppler indices A/B and PI on the vessel curvature and insonation angle; in fact, we recorded errors of about 25% when R(c) was 10 times larger than the radius of the vessel and about 100% when R(c) was five times larger than the radius of the vessel. Therefore, measurements of the UA at the PVC site should only be performed when the foetal bladder is empty.

The development of the bladder trigone, the center of the anti-reflux mechanism

The urinary tract is an outflow system that conducts urine from the kidneys to the bladder via the ureters that propel urine to the bladder via peristalsis. Once in the bladder, the ureteral valve, a mechanism that is not well understood, prevents backflow of urine to the kidney that can cause severe damage and induce end-stage renal disease. The upper and lower urinary tract compartments form independently, connecting at mid-gestation when the ureters move from their primary insertion site in the Wolffian ducts to the trigone, a muscular structure comprising the bladder floor just above the urethra. Precise connections between the ureters and the trigone are crucial for proper function of the ureteral valve mechanism; however, the developmental events underlying these connections and trigone formation are not well understood. According to established models, the trigone develops independently of the bladder, from the ureters, Wolffian ducts or a combination of both; however, these models have not been tested experimentally. Using the Cre-lox recombination system in lineage studies in mice, we find, unexpectedly, that the trigone is formed mostly from bladder smooth muscle with a more minor contribution from the ureter, and that trigone formation depends at least in part on intercalation of ureteral and bladder muscle. These studies suggest that urinary tract development occurs differently than previously thought, providing new insights into the mechanisms underlying normal and abnormal development.

Measurement of fetal urine production by three-dimensional ultrasonography in normal pregnancy

OBJECTIVES

Measurement of fetal urine production may provide a means of evaluating amniotic fluid volume, which is difficult to measure directly, and predicting fetal hypoxia. Although there have been some reports on fetal urine production, most of these have used two-dimensional (2D) ultrasonography to measure bladder volume. Three-dimensional (3D) ultrasonography is, however, known to be superior to 2D ultrasonography in some organ volume measurements. Thus, we undertook this study to measure bladder volumes using 3D ultrasonography and to establish a nomogram of fetal urine production rate (UPR) according to gestational age (GA).

METHODS

One hundred and fifty-four women with a normal singleton pregnancy at 24 to 40 weeks' gestation were enrolled in this cross-sectional study. The women had no medical or obstetric complications affecting amniotic fluid volume. Fetal bladder volume was measured using 3D ultrasound imaging and Virtual Organ Computer-aided AnaLysis (VOCAL) with a rotational angle of 30 degrees and manual surface tracing technique. Bladder volume was measured two or three times within a 5-10-min interval and fetal UPR was calculated from serial measurements. When measurements were performed more than twice, we used the mean rate of calculated UPRs. UPR was then plotted against GA to establish the nomogram.

RESULTS

Fetal UPR increased with GA from a median value of 7.3 mL/h at 24 weeks' gestation to 71.4 mL/h at term, and could be calculated from GA using the formula: Ln(UPR) = - 6.29582 + (0.43924 x GA) + (0.000432 x GA2), r2 = 0.63, P = 0.0046. Growth percentiles of UPR according to age are presented.

CONCLUSIONS

Fetal UPR can be easily measured by 3D ultrasound assessment of bladder volume. This modality may be a promising alternative to conventional methods of amniotic fluid volume measurement such as amniotic fluid index and single deepest pocket, and might be an alternative option for predicting fetal hypoxia.

Altered extracellular matrix expression in the diverted fetal sheep bladder

PURPOSE

It is unclear whether filling and emptying are important to bladder development. We tested this in an experimental preparation.

MATERIAL AND METHODS

Urinary diversion was performed in 7 fetal lambs at 90 days of gestation and 6 unoperated fetal lambs served as controls. Transmural sections were analyzed for changes in tissue layer thickness and/or composition after 14 days of urinary diversion. Matrix mRNA levels (collagen I and III, and FN) as well as the cytokines/growth factors IGF-1, EGR-1, WT-1 and BCL-2 were quantified by real-time polymerase chain reaction. Hydroxyproline measurements of total collagen and collagen subtype quantification were done by enzyme-linked immunosorbent assay.

RESULTS

Diverted fetal bladders showed a 27% and 57% decrease in mucosal and detrusor muscle layer thickness, respectively. In contrast, there was a 270% increase in serosal layer thickness in diverted bladders. The mRNA levels of COL1A1, COL3A1, IGF-1, EGR-1 and the anti-apoptotic gene BCL-2 were increased significantly in the serosal/detrusor layer of diverted bladders. In the mucosa levels of these mRNAs remained unchanged except for those of FN and WT-1, which were significantly decreased and increased, respectively. Total collagen, and type I and III collagen protein levels were significantly increased in diverted bladders.

CONCLUSIONS

The lack of mechanical loading in diverted bladders leads to the arrest of detrusor smooth muscle growth, and concurrent fibrosis and thickening of the serosal layer. Changes in the levels of IGF-1, BCL-2 and EGR-1 likely have regulatory roles that affect the smooth muscle phenotype in the detrusor layer.

Fetal urinary bladder rupture and urinary ascites secondary to posterior urethral valves. A case report

Megacystis is a typical prenatal sonographic finding in cases of lower urinary tract obstruction. Urinary bladder perforation represents a rare complication in this condition. We report on a boy with in utero bladder perforation and urinary ascites secondary to posterior urethral valves. The pre- and postnatal therapy is described and the current literature is reviewed.

Urothelial sonic hedgehog signaling plays an important role in bladder smooth muscle formation

During bladder development, primitive mesenchyme differentiates into smooth muscle (SM) under the influence of urothelium. The gene(s) responsible for this process have not been elucidated. We propose that the Sonic hedgehog (Shh) signaling pathway is critical in bladder SM formation. Herein, we examine the role of the Shh-signaling pathway during SM differentiation in the embryonic mouse bladder. Genes in the Shh pathway and SM expression in mouse embryonic (E) bladders (E12.5, 13.5, and 14.5) were examined by immunohistochemistry (IHC), in situ hybridization, and reverse transcription polymerase chain reaction (RT-PCR). To examine the effects of disrupting Shh signaling, bladder tissues were isolated at E12.5 and E14.5, that is, before and after bladder SM induction. The embryonic bladders were cultured on membranes floating on medium with and without 10 muM of cyclopamine, an Shh inhibitor. After 3 days, SM expression was examined by assessing the following: SM alpha-actin (SMAA), SM gamma-actin (SMGA), SM-myosin heavy chain (SM-MHC), Patched, GLI1, bone morphogenic protein 4 (BMP4), and proliferating cell nuclear antigen (PCNA) by IHC and RT-PCR. SM-related genes and proteins were not expressed in E12.5 mouse embryonic bladder before SM differentiation, but were expressed by E13.5 when SM differentiation was initiated. Shh was expressed in the urothelium in E12.5 bladders. Shh-related gene expression at E12.5 was significantly higher than at E14.5. In cyclopamine-exposed cultures of E12.5 tissue, SMAA, SMGA, GLI1, and BMP4 gene expression was significantly decreased compared with controls, but PCNA gene expression did not change. In cyclopamine-exposed E14.5 cultures, SMGA and SM-MHC gene expression did not change compared with controls. Using an in vitro embryonic bladder culture model, we were able to define the kinetics of SM- and Shh-related gene expression. Cyclopamine inhibited detrusor SM actin induction, but did not inhibit SM-MHC induction. SMAA and SMGA genes appear to be induced by Shh-signaling pathways, but the SM-MHC gene is not. Based on Shh expression by urothelium and the effects of Shh inhibition on bladder SM induction, we hypothesize that urothelial-derived Shh orchestrates induction of SM in the fetal mouse bladder.

Three-dimensional ultrasound fetal urinary bladder volume measurement: reliability of rotational (VOCALTM) technique using different steps of rotation

OBJECTIVE

The aim of the study was to investigate the inter- and intraobserver reliability in measuring the fetal bladder volume by 3d ultrasound imaging by VOCAL. In addition a comparison of 15 degrees and 30 degrees rotation steps calculation had been performed.

METHODS

Measurements (n = 240) of FB volume were performed in 30 low-risk patients with gestation times ranging from 22 to 39 weeks by two independent observers blind to each other. All fetuses were examined and no ultrasound detectable malformation was found. The volume for each FB was measured twice by the observers who used the Virtual Organ Computed-aided Analysis (VOCAL) technique. Distinct sets of 12 and 6 planes were obtained after sequential rotations of 15 degrees and 30 degrees, respectively. The internal contour of fetal bladder was determined manually and carefully as to exclude adjacent structures from volume calculation. Wilcoxon signed-rank test was used for the comparison of paired samples in the cases of replication within and between observers. Spearman's rank correlation was used to study the relationship among angles. Bland and Altman's graphical approach was used to investigate the agreement between observers.

RESULTS

Both techniques were shown to be highly reliable. No significant difference was found between the measurements of FB volume with the VOCAL technique by varying either the steps of rotation or the observers.

CONCLUSION

Excellent correlations were found for both observers in the use of rotation angles of 15 degrees and 30 degrees . Since a significantly faster evaluation was obtained by using a 30 degrees rotation step it must be preferred to assess the FB volume. Our results show that the VOCAL technique, with a plane rotation of 30 degrees , can be used in a simple way to estimate fetal urine production.

Vascular Endothelial Growth Factor Mediates Hypoxic Stimulated Embryonic Bladder Growth in Organ Culture

PURPOSE

Tissue hypoxia enhances embryonic angiogenesis at least in part by up-regulating vascular endothelial growth factor. Additionally, exogenous vascular endothelial growth factor-A enhances embryonic bladder explant growth. We hypothesized that developing bladders are hypoxic in vivo and oxygen tensions modulate explanted bladder growth by altering vascular endothelial growth factor-A expression.

MATERIALS AND METHODS

Embryonic day 14 mouse bladders were cultured in 20% O(2) or 3% O(2) atmospheres. Some cultures were supplemented with a vascular endothelial growth factor receptor 1/Fc chimera to block vascular endothelial growth factor bioactivity. After 6 days explant areas, DNA, protein, total cell numbers, and proportions expressing endothelial and smooth muscle markers were measured. Pimonidazole was administered to pregnant mice and hypoxia was sought in embryonic tissues by immunohistochemistry.

RESULTS

In vivo pimonidazole adducts and vascular endothelial growth factor-A immunolocalized to embryonic urothelium and bladders up-regulated total vascular endothelial growth factor-A between embryonic days 14 and 18. All growth parameters and vascular endothelial growth factor-A protein levels were enhanced in hypoxic vs normoxic culture. Addition of vascular endothelial growth factor receptor 1/Fc prevented this accelerated growth.

CONCLUSIONS

In vivo embryonic bladders are hypoxic and express vascular endothelial growth factor-A. In vitro, when oxygen tensions are manipulated, vascular endothelial growth factor-A protein positively correlates with the growth of whole explants as well as endothelium. Normal embryonic bladder development may be driven at least in part by hypoxic up-regulation of vascular endothelial growth factor-A.

Prenatal and Postnatal Neuromuscular Development of the Ureterovesical Junction

PURPOSE

The mechanisms underlying functional maturation of the ureterovesical junction during infancy are still not fully understood. We analyzed the development of smooth muscle components of the ureterovesical junction and their nerve supply in the fetal, newborn and adolescent pig.

MATERIALS AND METHODS

Bladder specimens were obtained from porcine fetuses at gestational ages 60 days (5) and 90 days (5), newborn piglets (5) and 6-month-old pigs (4). Serial sections of the ureterovesical junction were investigated by Masson's trichrome, and hematoxylin and eosin histological staining, enzyme immunohistochemistry for alpha-smooth muscle actin and desmin, as well as double immunofluorescence staining using the neuronal marker peripherin and smooth muscle actin.

RESULTS

At day 60 the detrusor muscle already consisted of distinctive muscle bundles with rich innervation, while the smooth muscle coat of the extravesical ureter and subsequently the intravesical ureter had only started to differentiate. At day 60 innervation of the extravesical ureteral smooth muscle was well developed, while the innervation of the intramural part did not mature until birth. Muscle fibers of the periureteral sheath were well distinguishable at day 60 but innervation of these fibers was sparse during fetal life and showed a remarkable increase during the postnatal period. All smooth muscle components showed a striking increase in muscle bulk between the neonatal and adolescent stages.

CONCLUSIONS

Our findings show that the smooth muscle components and innervation of the ureterovesical junction continue to mature during the postnatal period. This may have implications for managing ureterovesical junction disorders.

Ca 2+ Regulation in Detrusor Smooth Muscle From Ovine Fetal Bladder After In Utero Bladder Outflow Obstruction

PURPOSE

We characterized intracellular Ca(2+) regulation in fetal bladders following outflow obstruction by examining the Ca(2+) response to agonists in smooth muscle cells.

MATERIALS AND METHODS

Severe bladder outflow obstruction was induced in male fetal sheep by placing a urethral ring and urachal ligation midway through gestation at 75 days. Fetuses were examined 30 days after surgery. Intracellular Ca(2+) in single smooth muscle cells isolated from the bladder wall was measured with epifluorescence microscopy using fura-2(AM) during exposure to agonists, such as carbachol and adenosine triphosphate, and to other activators, such as caffeine and KCl.

RESULTS

Detrusor smooth muscle cells from obstructed bladders had resting intracellular Ca(2+) similar to that in sham operated controls. The maximal response to carbachol was decreased following obstruction (p <0.05). Construction of dose-response curves also demonstrated higher EC(50) (p <0.05). However, these changes were not mirrored by caffeine evoked Ca(2+) release, which was not significantly different between the obstruction group and sham operated controls. Kinetic analysis of carbachol transients further revealed an attenuated maximal rate of increase in obstructed bladders (p <0.01). The magnitude of intracellular Ca(2+) to purinergic neurotransmitter adenosine triphosphate was also found to be smaller in cells from obstructed bladders (p <0.05), although transmembrane influx by high K depolarization was not significantly affected.

CONCLUSIONS

Muscarinic and purinergic pathways were down-regulated in fetal detrusor muscle following outflow obstruction. These major functional receptors appeared to be more susceptible to obstruction than other Ca(2+) regulators. Their impairment may contribute to the compromised contractile function seen in in utero bladder outflow obstruction.

Molecular analysis of coordinated bladder and urogenital organ formation by Hedgehog signaling

The urogenital and reproductive organs, including the external genitalia, bladder and urethra, develop as anatomically aligned organs. Descriptive and experimental embryology suggest that the cloaca, and its derivative, the urogenital sinus, contribute to the formation of these organs. However, it is unknown how the primary tissue lineages in, and adjacent to, the cloaca give rise to the above organs, nor is bladder formation understood. While it is known that sonic hedgehog (Shh) is expressed by the cloacal epithelia, the developmental programs that regulate and coordinate the formation of the urogenital and reproductive organs have not been elucidated. Here we report that Shh mutant embryos display hypoplasia of external genitalia, internal urethra (pelvic urethra) and bladder. The importance of Shh signaling in the development of bladder and external genitalia was confirmed by analyzing a variety of mutant mouse lines with defective hedgehog signaling. By genetically labeling hedgehog-responding tissue lineages adjacent to the cloaca and urogenital sinus, we defined the contribution of these tissues to the bladder and external genitalia. We discovered that development of smooth muscle myosin-positive embryonic bladder mesenchyme requires Shh signaling, and that the bladder mesenchyme and dorsal (upper) external genitalia derive from Shh-responsive peri-cloacal mesenchyme. Thus, the mesenchymal precursors for multiple urogenital structures derive from peri-cloacal mesenchyme and the coordination of urogenital organ formation from these precursors is orchestrated by Shh signals.

A comparative ontogenic study of urinary bladder: impact of the epithelial differentiation in embryonic and newborn rats

The present study aimed to show the cellular and subcellular distribution of glycogen content during the differentiation of urothelial cells from simple cuboidal to stratified transitional epithelium. Bladder samples were taken from rat embryos on the 15th to 19th days and newborn at 21st day. During the development of the bladder, the formation of fusiform vesicles, asymmetric unit membrane (AUM) and microridges were examined with staining with haematoxylin-eosin and periodic acid Schiff for light microscope and periodic acid-thiocharbohydrazide-silver proteinate for transmission electron microscope. The topographical changes of luminal differentiation were examined with the scanning electron microscope. The urothelium was simple cuboidal from 15th till the 17th days of gestation. Glycogen content was present in the cytoplasm till the 18th day of gestation. At the early stage (16th day) of gestation, the apical surface contains microvilli that points the undifferentiated cells. The density of microvilli decreased and ropy microridges appeared at the 17th day of gestation. The small discoid vesicles lined with AUM developed at the apical cytoplasm of the surface cells at the 17th day of gestation. After this stage, both the density of microridges and large and elongated fusiform vesicles increased. The differentiation of the urothelium begins with the formation of the round and small vesicles, continues with the formation of the AUM and at the final stage there is a decrease in both glycogen content and the appearance of the microridges at the luminal surface of the urothelial cells.

Gender Specific Chronological and Morphometric Assessment of Fetal Bladder Wall Development

PURPOSE

To enhance our understanding of sonographically visible alterations in bladder wall thickness, we delineated phenotypic changes occurring in developing smooth muscle cells of the fetal and postnatal bladder with respect to gender specific differences.

MATERIALS AND METHODS

Bladders of 30 male and 18 female fetuses and 4 stillborn infants were immunostained with an alpha-smooth muscle actin antibody. Morphological and morphometric assessment was performed with the assistance of an image analysis system.

RESULTS

Alpha-smooth muscle actin expression in fetal bladder wall was detectable at 9 weeks of gestation. Bladder wall thickness and mean profile area of smooth muscle bundles increased significantly with advancing gestation, mediated by linear growth patterns. Fetal bladder wall development occurred uniformly, unrelated to gender.

CONCLUSIONS

Although the lower urinary tract emerges in a gender specific way, our results suggest that in normal fetal growth detrusor muscle formation proceeds independent of genital sex.

DeltaNp63 plays an anti-apoptotic role in ventral bladder development

The bladder, the largest smooth-muscle organ in the human body, is responsible for urine storage and micturition. P63, a homolog of the p53 tumor-suppressor gene, is essential for the development of all stratified epithelia, including the bladder urothelium. The N-terminal truncated isoform of p63, DeltaNp63, is known to have anti-apoptotic characteristics. We have established that DeltaNp63 is not only the predominant isoform expressed throughout the bladder, but is also preferentially expressed in the ventral bladder urothelium during early development. We observed a host of ventral defects in p63-/- embryos, including the absence of the abdominal and ventral bladder walls. This number of ventral defects is identical to bladder exstrophy, a congenital anomaly exhibited in human neonates. In the absence of p63, the ventral urothelium was neither committed nor differentiated, whereas the dorsal urothelium was both committed and differentiated. Furthermore, in p63-/- bladders, apoptosis in the ventral urothelium was significantly increased. This was accompanied by the upregulation of mitochondrial apoptotic mediators Bax and Apaf1, and concurrent upregulation of p53. Overexpression of DeltaNp63gamma and DeltaNp63beta in p63-/- bladder primary cell cultures resulted in a rescue, evidenced by significantly reduced expressions of Bax and Apaf1. We conclude that DeltaNp63 plays a crucial anti-apoptotic role in normal bladder development.

Superficial cell differentiation during embryonic and postnatal development of mouse urothelium

After drastic urothelial destruction around birth and around postnatal day 6, mouse urothelial renewal starts each time de novo. The differentiation of superficial cells during urothelial restoration was followed for the first time from embryonic day 15 to postnatal day 6 by the detection of differentiation markers: cytokeratins, uroplakins and apical membrane specialization. The differentiation markers of short-lived superficial cells were studied before and after urothelial destruction. Three distinctive types of superficial cells, typical for certain developmental period, were characterised: cells at low differentiation stage with microvilli and cilia, expressing CK7 and CK18, detected on embryonic day 15; cells at advanced differentiation stage with star-like arrangement of prominent membrane ridges, expressing CK7 and CK20, present between the two urothelial destruction events; highly differentiated cells with typically jagged apical surface, expressing CK7 and CK20, found twice during development. This cell type appears for the first time on embryonic day 18 as the terminal stage of embryonic differentiation. It was found again on postnatal day 6 as an initial stage of differentiation, leading toward terminally differentiated cells of the adult urothelium. Our work proves that apical membrane specialization is the most valuable differentiation marker of superficial cells.

Reevaluation of the fetal muscle development of the vesical trigone

PURPOSE

Fetal development of the interureteral muscle, a precondition of a sufficient opposite anchoring of the ureterovesical junction, and the muscle architecture of the bladder neck was investigated using immunohistochemical analysis.

MATERIALS AND METHODS

We investigated the ureterotrigonal units in 38 fetal specimens (16 females, 22 males) and 7 newborns (2 females, 5 males) at 9 to 40 weeks of gestation. Histology was based on serial consecutive sections of the bladder base. Anti-human alpha-smooth muscle actin immunostaining was used to demonstrate the time course of muscle development and arrangement.

RESULTS

A much earlier developmental stage of the trigone muscle configuration during fetal life was noted than has been reported to date. The condensation of myoblasts located mainly in the dorsal wall of the trigone and at the bladder outlet was present beginning at 12 weeks of gestation. The trigone develops continuously as a single circular muscular layer corresponding to the posterior part of the vesical sphincter muscle. Muscle fibers forming the interureteral junction were demonstrable beginning at 14 weeks of gestation.

CONCLUSIONS

There is a close connection between the trigonal smooth muscle layer and the vesical sphincter muscle forming the main part of the trigone by 12 weeks of gestation. Fetal development of the trigone, in particular the muscle architecture of the bladder neck, which consists of only a ring-shaped muscular layer, and the transverse oriented interureteral muscle results in a functional entity representing the anatomical basis for a competent ureterovesical junction.