Effects of early vesicostomy in obstructive uropathy on bladder development

Fetal Lower Urinary Tract Obstruction: Current Diagnostic and Therapeutic Strategies and Future Directions

BACKGROUND

Fetal lower urinary tract obstruction (LUTO) is a rare congenital anomaly in which the bladder cannot empty properly. The clinical presentation is variable. On the severe end of the spectrum, the amniotic fluid index can be sufficiently low, resulting in fetal lung development that is incompatible with life outside the womb. The pressure in the urinary tract system can also result in severe damage to the kidney, resulting in renal failure in utero or in the first couple years of life. Therefore, much work has been done to determine which fetuses need intervention in utero to allow for survival outside of the womb and avoidance of end-stage renal disease. Multiple therapies have been developed to relieve the obstruction in utero with the mainstay being vesicoamniotic shunting and posterior urethral valve ablation.

SUMMARY

While much has been investigated to determine which fetuses would benefit from fetal intervention, the current indications are not without their flaws. This review describes the current indications and their shortcomings, as well as new experimental methods of determining need for intervention. Additionally, this review describes the milestone animal studies that established the challenges of current fetal interventions and the utility of an experimental valved shunt in sheep over the last 20 years.

KEY MESSAGES

Our understanding of LUTO and which fetuses benefit from in utero intervention has grown over the last 20 years. However, traditional markers have proven to be less predictive than previously thought, opening the door to exciting new advances. Vesicoamniotic shunting, while lifesaving, does not preserve bladder function and frequently dislodges. Animal studies over the last 20 years have established the utility of a valved shunt to maintain bladder function. Current advances are working to create such a shunt that can be percutaneously deployed and have greater adherence to the bladder wall to avoid dislodgement.

Perinatal Outcomes of Fetal Lower Urinary Tract Obstruction After Vesicoamniotic Shunting Using a Double-Basket Catheter

OBJECTIVES

To evaluate the perinatal survival and renal function of fetuses with lower urinary tract obstruction (LUTO) who underwent vesicoamniotic shunting using a double-basket catheter METHODS: We retrospectively reviewed 32 fetuses with LUTO who underwent vesicoamniotic shunting using a double-basket catheter between 1998 and 2013.

RESULTS

Among the 32 fetuses examined, 5 died because of termination of pregnancy, and 2 died in utero. The median gestational age at diagnosis was 15.5 (range, 10.0-27.3) weeks, and that at initial shunting was 17.1 (range, 12.3-32.2) weeks. Shunt dislocation or occlusion occurred in 18 of 42 procedures (42.8%). The median gestational age at delivery for the 25 live births was 35.5 (range, 28-40) weeks. Postnatal diagnosis revealed posterior urethral valves in 15 fetuses, a cloacal anomaly in 7, and urethral stenosis in 3. Three neonatal deaths occurred, resulting in an overall perinatal survival rate of 68.8% (22 of 32). The rates of normal renal function were 40.6% (13 of 32) at 28 days and 40% (10 of 25) at 2 years after birth. The absence of oligohydramnios after shunting was the only prognostic factor for normal renal function at 2 years (P < .05).

CONCLUSIONS

Vesicoamniotic shunting may be helpful for fetuses with LUTO.

Fetal Lower Urinary Tract Obstruction (LUTO): a practical review for providers

Fetal lower urinary tract obstruction (LUTO) is a serious condition, which commonly results in marked perinatal morbidity and mortality. The characteristic prenatal presentation of LUTO includes an enlarged bladder with bilateral obstructive uropathy. While mild forms of the disease result in minimal clinical sequelae, the more severe forms commonly lead to oligohydramnios, dysplastic changes in the fetal kidneys, and ultimately result in secondary pulmonary hypoplasia. The aim of this review is to provide practitioners with a practical and concise overview of the presentation, evaluation, and treatment of LUTO.

Can a pressure-limited V-A shunt for obstructive uropathy really protect the kidney?

BACKGROUND

In our fetal lamb model of lower urinary tract obstruction, a valved shunt preserves bladder function. This study investigates the effects on renal histology.

METHODS

We created obstructive uropathy (OU) in 60-day gestation fetal lambs, ligating the urethra and urachus, and delivering them at term (130-145days). We compared renal histology in 4 groups: group A-OU without shunt, group B-low-pressure shunt (15-54mmH2O), group C-high-pressure shunt (95-150mmH2O). Shunts were inserted 3weeks post-obstruction. Group D were normal controls.

RESULTS

We delivered 32 fetuses from 23 ewes: 13 fetuses in group A (9 survived), 6 fetuses in group B (5 survived), 7 fetuses in group C (5 survived), and 6 fetuses in group D. Histologically, we found renal tubular distention, vacuolated degeneration of tubular epithelial cells in 7 lambs, and cyst formation in 4 lambs in group A. There was renal tubular distention in two lambs, and cyst formation in one lamb in both groups B and C, with vacuolated degeneration of tubular epithelial cells observed in all but 1 lamb in each group.

CONCLUSIONS

V-A shunting prevents multicystic dysplastic kidney (MCDK). Some lambs have renal tubular distention and vacuolated degeneration of renal tubular epithelial cells.

Bladder changes after several coverage modalities in the surgically induced model of myelomeningocele in lambs

OBJECTIVE

To assess the presence of early bladder abnormalities in a prenatally corrected and uncorrected animal model of Myelomeningocele (MMC).

METHOD

A MMC-like lesion was surgically created in 18 fetal lambs between the 60th and the 80th day of gestation. Eight of them did not undergo fetal repair (group A), three were repaired with an open two-layer closure (group B), three using BioGlue® (groupC) and four fetoscopically (group D). At term, bladders were examined macroscopically and histopathological changes were assessed using H-E and Masson Trichrome.

RESULTS

Five animals in group A (5/8, 62%), two in group B (2/3, 66%), one in group C (1/3, 33%) and one in group D (1/4, 25%) survived. Macroscopically bladders in group A were severely dilated and showed thinner walls. Microscopically they showed a thin layer of colagenous tissue (Blue layer. BL) lying immediately subjacent to the urothelium. The muscular layers were thinner. Non compliant pattern with thick wall and low capacity was also found in the non corrected model. Group B and the control showed preservation of muscular layers and absence of BL. Groups C and D presented BL but also preservation of muscular layers.

CONCLUSION

Bladder changes in a surgically-induced model of MMC can be described using histopathological data. Both extremes of bladder changes can be observed in the model. These changes were completely prevented with open fetal surgery and partially with other coverage modalities.

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.

Valved shunt as a treatment for obstructive uropathy: does pressure make a difference?

PURPOSE

A valved ventriculo-peritoneal shunt (V-P shunt) as a vesico-amniotic shunt (V-A shunt) preserves the filling/emptying cycle and normal bladder development in fetal lambs with bladder outlet obstruction. The optimal pressure for such shunts is unknown.

MATERIALS AND METHODS

We created obstructive uropathy in 60-day gestation fetal lambs. A V-A shunt was placed 3 weeks later, using a low-pressure (Group L: 15-54 mmH2O) or a high-pressure (Group H: 95-150 mmH2O) V-P shunt. We included non-shunted (obstructive uropathy, Group O) and control lambs (Group C). All were delivered at 130 days. Bladder volumes, bladder thickness, renal and bladder histology were compared.

RESULTS

Seventeen lambs had an obstructive uropathy created. Five Group L (four survived), four Group H (three survived) and five Group O survived. Body weight and crown-to-rump lengths of the three groups were not significantly different. Group H lambs had a dilated urachus, urinary ascites and severe ureteral dilatation similar to Group O lambs. There were four Group C lambs. Bladder volume was 10, 15 and 1,150 ml in Group H, 115 ± 67.9 ml in Group L, 128 ± 99.8 ml in Group O and 24.5 ± 3.84 ml in Group C. Unlike Group O lambs, Group L did not have urinary ascites, urinomas or renal dysplasia.

CONCLUSION

Low-pressure shunts preserved both bladder volume and renal development. High-pressure shunts did neither.

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 surgery for severe lower urinary tract obstruction

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

Bladder development following bladder outlet obstruction in fetal lambs: optimal timing of fetal therapy

BACKGROUND

Lower urinary tract obstruction causes both renal failure and bladder dysfunction after birth. This study examined the early bladder wall changes after creating an obstructive uropathy focusing on bladder wall thickness and muscle integrity.

METHODS

We created obstructive uropathy in fetal lambs at 60 days' gestation, ligating the urethra and urachus. The fetuses (n = 28) were delivered at 48 hours and 3, 4, 5, 7, and 14 days after obstruction and at term (145 days' gestation). Sham-operated lambs were used as controls (n = 20). Histology samples were stained using α-smooth muscle actin) immunohistochemistry and also hematoxylin-eosin, Masson trichrome, and colloidal Fe stain.

RESULTS

The bladder wall initially expanded and stretched. By day 4, the bladder wall became thicker. Histologically, the bladder in obstructed lambs demonstrated a prominent submucosal fibrotic change by 7 days. The mean bladder wall thickness at 14 days after obstruction was thicker than controls, and fibrosis was prominent.

CONCLUSION

The initial changes in the bladder wall were expansion of the muscle component followed by fibrosis. The bladder wall thickness dramatically increased 4 to 7 days after obstruction. We conclude that shunting operations to preserve bladder function may be needed earlier than expected.

Can a pressure-limited vesico-amniotic shunt tube preserve normal bladder function?

INTRODUCTION

We have previously shown that a vesico-amniotic shunt (V-A shunt) produces fibrotic bladders with poor compliance in normal fetal lambs. We hypothesized that using a ventriculo-peritoneal shunt (V-P shunt) as a V-A shunt in normal bladders may preserve the filling/emptying cycle and normal bladder development.

MATERIALS AND METHODS

The V-A shunting in normal fetal lambs was performed at 74 days of gestation using a V-P shunt (group A) and a free-draining shunt tube (group B). Sham-operated lambs were used as controls (group C). They were all delivered at term (145 days), and the pressure-volume curve, bladder volume, and histologic features of the bladder wall were compared.

RESULT

The mean bladder volume in group B (n = 5), 5 +/- 2.4 mL, was significantly smaller (P < .01) than that in group A (n = 6), 53 +/- 14 mL, and group C (n = 10), 57.3 +/- 12 mL. The bladder wall thickness in group A was 338 + 94.2 microm; group B, 741 +/- 128 microm; and group C, 374 +/- 120 microm. Group B bladders had very poor compliance with thick bladder wall (P < .01). Histologically, group B bladders showed prominent submucosal fibrotic change, but group A bladders were similar to controls.

CONCLUSION

This study shows that a pressure-limited shunt tube for V-A shunting preserves the normal fetal bladder development.

Is a vesicoamniotic shunt intrinsically bad? Shunting a normal fetal bladder

INTRODUCTION

We previously demonstrated that in utero vesicoamniotic shunting of obstructive uropathy in fetal lambs produces a shrunken noncompliant bladder. We hypothesized that the normal fetal bladder filling and emptying cycle in fetal life is critical to the development of normal bladder function.

MATERIALS AND METHODS

We placed vesicoamniotic shunts in 4 normal fetal lambs at 74 days' gestation. The fetuses were delivered at term (145 days), and bladder volume and compliance were measured and compared with those measurements in 3 normal term fetuses. The lambs were then killed and the renal tracts and bladders removed submitted to histologic examination.

RESULTS

All shunted lambs survived to term. Three normal control lambs were delivered at term. The mean bladder volume in shunted lambs was 4 +/- 2.8 mL (n = 4) compared with 60 +/- 17 mL (n = 3) in control lambs (P < .05). Bladders in the shunted lambs had very poor compliance compared with normal lambs' bladders. Histologic examination of the shunted bladders showed increased fibrosis and distortion of the muscle layers compared with control bladders.

CONCLUSION

Even in the absence of obstruction, preventing normal bladder filling and emptying in fetal life produces fibrotic bladders with poor compliance.

Pressure-limited vesico-amniotic shunt tube for fetal obstructive uropathy

INTRODUCTION

In utero shunting (vesico-amniotic shunt) of obstructive uropathy in fetal lambs produces a shrunken, noncompliant bladder. We hypothesized that using a ventriculo-peritoneal shunt for the vesico-amniotic shunt may preserve the filling/emptying cycle and thus normal bladder development.

MATERIALS AND METHODS

We created obstructive uropathy in 60-day gestation fetal lambs, ligating the urethra and urachus. Vesico-amniotic shunting was performed 21 days later using the valve end of a ventriculo-peritoneal shunt (valve shunt) or silastic tubing (nonvalve shunt). They were delivered at term (145 days), and the bladder volume was measured and compared to normal term fetuses. The lambs were sacrificed, and the kidneys and bladder removed for histology.

RESULTS

Twenty-seven lambs were shunted. Of 14 valve shunts, 8 were effective. Of 13 nonvalve shunts, 11 were effective. The mean bladder volume was 57 +/- 41 mL with a valve shunt and 8.8 +/- 4.7 mL with a nonvalve shunt (P < .05) (normal term lambs, 65 +/- 18 mL, n = 5). Histology of the shunted bladders showed increased fibrosis in the submucosal and muscle layers. This was less obvious in lambs with a valve shunt.

CONCLUSION

A pressure controlled shunt for fetal obstructive uropathy improves bladder volume but does not prevent bladder wall fibrosis.

Early bladder wall changes after creation of obstructive uropathy in the fetal lamb

Vesico-amniotic shunting of obstructive uropathy in fetal lambs produced a thick-walled, poorly compliant bladder. We report the early histological changes in the obstructed bladder wall. We created an obstructive uropathy in fetal lambs at 60 days gestation by ligating the urethra and urachus. Vesicostomy or vesico-amniotic shunt tube insertion and biopsy of the bladder wall were performed 21 days later. The fetuses were delivered at term (145 days) and the kidneys and bladder sampled for histology. Colloidal iron (Col Fe), and alpha-smooth muscle actin (alpha-SMA) immunohistochemical stains were used for these samples. Seventeen fetuses were shunted with 15 biopsies taken at that time. Six (shunt failure or missed urachal ligation) were excluded. All biopsies taken at shunting had positive Col Fe and alpha-SMA. Term lambs had mild multicystic dysplastic kidney (MCDK) in five, severe MCDK in two, and hydronephrosis in four. All bladders had small volume and were severely fibrotic. Fetal shunt operations 3 weeks after the creation of obstructive uropathy provided partial preservation of renal histology but did not preserve normal bladder histology. We suggest that the high hyaluronic acid synthesis activity or hyperplasia of the myofibroblasts in the dilated fetal bladder wall at the time of shunting results in irreversible damage to the developing bladder muscle and fibrosis.

Experimental short-term partial fetal bladder outflow obstruction: II. Compliance and contractility associated with urinary flow impairment

PURPOSE

Posterior urethral valves (PUV) is the commonest cause of congenital bladder outlet obstruction. Despite valve ablation in the neonatal period, up to 70% of patients develop renal failure by their teenage years, and progressive bladder dysfunction. This study forms part of a continuing project examining the relationship between severity and duration of obstruction and urinary tract dysfunction. Here is the assessed result of short-term (9-day) obstruction.

MATERIALS AND METHODS

Fourteen male fetal lambs at 75 days' gestation were assigned to one of three groups: urachal ligation, urachal ligation with partial urethral obstruction, sham-operated controls. Pregnancy proceeded for 9 days. At autopsy, filling cystometry was performed with the urinary tract in situ and the bladder harvested for nerve counts using PGP 9.5 immunohistochemistry, or in vitro measurement of contractile function.

RESULTS

Obstruction was associated with an increase in bladder:fetal weight ratio. Compliance was variable in the obstructed bladders, but the calculated wall stress per unit strain was either similar or less than controls. Nerve-mediated or agonist-induced contraction magnitude in tissue from obstructed bladders and nerve counts did not differ from controls.

CONCLUSIONS

Nine days of outflow obstruction at mid-gestation generated a bladder of increased weight but without evidence of contractile failure. An increase in bladder compliance as a function of bladder growth was observed even at this stage, and represents one of the initial responses to outflow tract obstruction.

Vesicoamniotic shunt for complete urinary tract obstruction is partially effective

PURPOSE

The long-term outcome for children after antenatal intervention for obstructive uropathies is disappointing. We reported that renal dysplastic changes are well established 3 weeks after obstruction in a fetal lamb model. We used this model to explore renal development and bladder function after fetal intervention.

METHODS

We created an obstructive uropathy in fetal lambs at 60 days gestation by ligating the urethra and urachus. A vesicostomy (female) or urethrostomy (male) were performed 21 days later. The fetuses were killed at term (145 days) and bladder volume and compliance were measured. The urinary tract was processed for histologic examination.

RESULTS

Twenty two fetuses were shunted. Nine were miscarried or were still-born. Thirteen survived, and 11 had a successful shunt with a small bladder (8 +/- 5 mL) compared with controls (71 +/- 19 mL) (P < .05). Shunted bladders had poor compliance. Histologically, they had thickened submucosal connective tissue with hypertrophied muscle. Histology of the renal tissue demonstrated relatively well-preserved renal architecture with reduced nephron mass (oligonephronia) in 2 lambs and multicystic dysplastic change in 3. Six (55%) had normal nephrogenesis.

CONCLUSIONS

In our model, shunt operations after obstructive uropathy fail to preserve bladder function. Shunting ameliorated the development of cystic dysplasia, but half of the lambs had oligonephronia or multicystic dysplastic kidney. These might develop renal failure later in life.

Discordant Lower Urinary Tract Obstruction in Early Twin Gestations

OBJECTIVE

To report our experience with the management of twin pregnancies discordant for lower urinary tract obstruction.

METHODS

Cases of twin pregnancies discordant for lower urinary tract obstruction were identified from our fetal medicine database. Information on ultrasonographic findings, antenatal course, pregnancy complications, and perinatal outcome was obtained by reviewing medical records or contacting the referring obstetricians.

RESULTS

Five twin pregnancies discordant for lower urinary tract obstruction were diagnosed between 11 and 15 weeks of gestation. There were 3 dichorionic and 2 monochorionic pregnancies (1 diamniotic and 1 monoamniotic). The dichorionic pregnancies were managed conservatively, resulting in a pregnancy loss of both twins in 1 case, a single fetal death at 29 weeks in 1 case, and an early neonatal death due to lung hypoplasia of the affected twin in 1 case. On the other hand, both monochorionic twin pregnancies were managed with serial vesicocenteses. In both cases, the prenatal course was complicated, 1 by premature rupture of the membranes and the other by cord entanglement, requiring delivery at 29 and 31 weeks, respectively. Among the 4 continuing pregnancies with complete perinatal outcome, none of the affected twins survived, and the structurally normal twins were delivered between 29 and 36 weeks and discharged from the hospital in good condition.

CONCLUSION

Twin pregnancies discordant for lower urinary tract obstruction are at high risk of perinatal death and premature delivery. Prenatal intervention seems not to be associated with an improved perinatal outcome of the affected twin, but it may be beneficial in selected cases to attain viability of the unaffected twin.