Lower urinary tract obstruction: clinical and experimental aspects

Prenatal and postnatal urinary tract dilation: advantages of a standardized ultrasound definition and classification

Urinary tract dilatation is identified sonographically in 1-2% of fetuses and reflects a spectrum of possible nephro-uropathies. There is significant variability in the clinical management of individuals with prenatal urinary tract dilatation to postnatal urinary pathologies, because of a lack of consensus and uniformity in defining and classifying urinary tract dilation. Ultrasonography is the first step to screen and diagnose kidneys and the urinary tract diseases of the children. The need for a correct ultrasound approach led to the realization of algorithms aimed at standardizing the procedures, the parameters and the classifications. Our objective was to highlight the strengths of the Classification of Urinary Tract Dilation (UTD) suggested by the Consensus Conference which took place in 2014 with the participation of eight Scientific Societies and was subsequently published on the Journal of Pediatric Urology. Before its spread out, the definition of UTD was not uniform and the ultrasonographic measurements were not clearly defined, leading to misunderstandings between physicians. The Classification by the Consensus Conference of 2014 represents a revolutionary tool for the diagnosis and management of UTD. Furthermore, the parameters suggested by the classification proposed are applicable for both prenatal and postnatal classification, ensuring a correct follow-up in children with UTD whose diagnosis had been already made during pregnancy.

The management of antenatal hydronephrosis detected on routine prenatal ultrasound

Antenatal hydronephrosis (ANH) is a common abnormality seen on routine prenatal ultrasound. Although this condition is invariably transient and benign, it can result in a deterioration in renal function and other significant co-morbidities. Once detected, careful ultrasound monitoring of the ANH is recommended during pregnancy. Postnatal antibiotic prophylaxis should be commenced after birth whilst investigating in a stepwise fashion in order to elucidate the underlying cause of the hydronephrosis. The aim is to preserve renal function, prevent urinary tract infection, and protect the upper tracts.

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.

Treatment and outcome of prenatally detected newborn hydronephrosis

OBJECTIVE

For neonates with antenatally diagnosed primary ureteropelvic junction (UPJ)-type hydronephrosis, to attempt to clarify and refine criteria for establishing optimal follow-up and treatment guidelines.

PATIENTS AND METHODS

A total of 162 newborns (228 hydronephrotic kidneys) with this condition were prospectively followed and treated by the same surgeon in 2001-2005 for a mean of 53 (13-72) months. Ultrasonography and diuretic renogram were used for diagnosis and follow up, and Onen's grading system to determine degree of hydronephrosis.

RESULTS

On first postnatal ultrasound, the severity of hydronephrosis was grade 1 in 152 kidneys (surgery, 0%), 2 in 41 (surgery, 19.5%), 3 in 19 (surgery, 42.1%), and 4 in 16 kidneys (surgery, 93.8%). All the grade 1 cases resolved spontaneously without renal deterioration (renal function >40%). Renal function ranged between 7% and 34% in grade 4 patients. Overall, 201 hydronephrotic kidneys (88.2%) resolved spontaneously, while 27 (11.8%) required pyeloplasty because of evidence of obstructive injury, including increased hydronephrosis in 14/27 (6/27 had less than 10% decrease in renal function), greater than 10% decrease of renal function in 9/27, and greater than 10% decrease of renal function as well as increased hydronephrosis in 4/27 patients (15%).

CONCLUSION

In most cases, neonatal hydronephrosis is a relatively benign condition that can be followed safely by an initial non-operative approach unless there is evidence of obstructive injury. A follow-up protocol that permits early identification of a limited number of kidneys that may develop signs of obstruction and require pyeloplasty is crucial for a favorable outcome in patients with primary UPJ-type hydronephrosis. Onen's hydronephrosis grading system promises an easier and more appropriate follow up and timely treatment for children with this condition. A sufficient follow-up interval, especially during the first 3 years of life, is essential to help prevent permanent loss of renal function in kidneys that do develop signs of obstruction.

An alternative grading system to refine the criteria for severity of hydronephrosis and optimal treatment guidelines in neonates with primary UPJ-type hydronephrosis

OBJECTIVE

We present our alternative hydronephrosis grading system (AGS) in an attempt to establish optimal treatment guidelines, and clarify and refine the criteria for severity of hydronephrosis in neonates.

PATIENTS AND METHODS

A total of 162 newborns (228 affected kidneys) with antenatally diagnosed primary ureteropelvic junction-type hydronephrosis were prospectively followed and treated by the same surgeon for a mean of 46 (6-65) months. Ultrasonography and diuretic renogram were used for diagnosis and follow up. Society for Fetal Urology (SFU) grading system, anteroposterior diameter of renal pelvis (APDRP) and our AGS were used to determine the degree of hydronephrosis. AGS: 0, no hydronephrosis; 1, dilatation of renal pelvis alone; 2, plus caliceal dilatation; 3, plus <1/2 (mild-to-moderate) renal parenchymal loss; 4, plus >1/2 (severe) renal parenchymal loss (cyst-like kidney with no visually significant renal parenchyma).

RESULTS

On the first postnatal ultrasound, the severity of hydronephrosis was SFU< or =2 in 152 kidneys (surgery, 0%), SFU-3 in 41 kidneys (surgery, 19.5%) and SFU-4 in 35 kidneys (surgery, 68.6%). The follow up, treatment and outcome of SFU-1 and SFU-2 patients were similar; all resolved spontaneously without renal deterioration (renal function >40%). Renal function ranged between 7% and 39% in SFU-4 patients. Intrarenal pelvis was found in one patient with an APDRP of <15 mm, seven patients of 16-30 mm, and five patients of >30 mm. Overall, 201 hydronephrotic kidneys (88.2%) resolved spontaneously while 27 (11.8%) required pyeloplasty.

CONCLUSION

Neither an SFU grading system nor measurement of APDRP is the gold standard in determining the severity of hydronephrosis. Both methods may fail, particularly in children with intrarenal pelvis configuration or SFU-4 hydronephrosis. Our AGS promises easier follow up and more timely treatment.

Intrinsic expression of Th2 cytokines in urothelium of congenital ureteropelvic junction obstruction

BACKGROUND

The cytokine-producing ability of urothelium, a urinary tract barrier between urine and underlying connective tissue, may exacerbate the pathogenesis of congenital ureteropelvic junction obstruction (UPJ-O) disease. A role for urothelium in human urinary tract obstruction has rarely been described. In this study, we investigated the immunopathologic characteristics of, and cytokine production by, urothelium in children with congenital UPJ-O.

METHODS

Twenty-four children with congenital UPJ-O who had received pyeloplasty were enrolled. Morphologic abnormalities and pathologic and inflammatory changes of UPJ-O segments were studied. Expression of cytokines and chemokines in urothelium was investigated and compared with control tissue by immunohistochemistry (IHC), in situ hybridization (ISH), and urinary enzyme-linked immunosorbent assay (ELISA).

RESULTS

Atypical or simple hyperplasia of the urothelium with evidence of Ki67 over-expression was found frequently in UPJ-O. There were variable degrees of inflammatory cell and eosinophil infiltration. Augmented expression of IL-5 and eotaxin detected by IHC and ISH, and enhanced degranulation of tissue mast cells were observed in the urothelium of UPJ-O segments. IL-4, IFN-gamma, and TNF-alpha were undetectable. Significantly higher levels of urinary IL-5, IFN-gamma, and eotaxin were detected in urine collected from the obstructed kidney. Among these, high urinary IL5 and/or IFN-gamma levels were associated with more severe obstructive uropathy (P < 0.05).

CONCLUSION

Urothelium, like intestinal and respiratory epithelia, plays an active role in immunoregulation and may contribute to exacerbation of the pathogenesis of congenital UPJ-O. Many eosinophil-associated disease cytokines, which can lead to the degranulation of mast cells, are predominant regulators in UPJ-O urothelium.

A functional immature model of chronic partial ureteral obstruction

BACKGROUND

The most common nonlethal congenital anomaly of the urinary tract is ureteral obstruction without dysplasia. Although rarely progressive, the morbidity associated with metabolic and surgical management is considerable. Our study was designed to measure local and systemic pathophysiologic mechanisms in an immature model of chronic partial unilateral ureteral obstruction (UUO) after completion of glomerulogenesis.

METHODS

A partial UUO was created by the method of "psoas wrap" in young male weanling rats. Control animals were sham operated. Three groups were divided as follows: sham (N= 15), UUO (N= 18), and UUO + angiotensin-converting enzyme (ACE) (N= 16) inhibitor, enalapril. Renal glomerular and tubular functions were determined by creatinine and uric acid clearances. Diuresis was assessed by urine volume, osmolality, and fractional solute excretions from samples above and below the obstruction. Proteinuria was determined by the urine protein/creatinine ratio (Up/c).

RESULTS

Proteinuria was attenuated in UUO + ACE-treated animals. The hyperuricemia of the immature UUO animals was avoided by an increase in the clearance of uric acid in the UUO + ACE-treated group. Fractional solute excretions suggested a diversion of diuresis to the contralateral unobstructed kidney.

CONCLUSION

Angiotensin blockade during chronic UUO in young rats affords protection by attenuating proteinuria, promoting uricosuria, and diverting solute diuresis. These data suggest a complex interaction of local and systemic mechanisms unique to the maturing kidney.

Massive bilateral perirenal hematoma following urinary catheterization for urinary obstruction

Urinary tract obstruction is a common problem associated with many complications. Decompression of an enlarged bladder has been associated with several complications, mainly vesicular bleeding. We report a case of a 42-year-old male patient who developed bilateral renal subcapsular hematomas secondary to relief of an extremely enlarged bladder.

Factors associated with the outcomes of children with unilateral ureteropelvic junction obstruction

PURPOSE

Children with congenital unilateral ureteropelvic junction obstruction were evaluated with 99mtechnetium-labeled diethylenetriaminepentaacetic acid furosemide renal scans (DTPA) to determine the correlation of tubular function tests, growth factors and renal function.

MATERIALS AND METHODS

A total of 38 children diagnosed with congenital unilateral ureteropelvic junction obstruction and recipients of dismembered pyeloplasty were prospectively studied. Before pyeloplasty split renal tubular function, creatinine clearance, urinary growth factors and a marker for apoptosis of each kidney were examined. Renal function of the obstructed kidney was evaluated by DTPA before and after pyeloplasty. Initially patients with DTPA greater than 40% were designated group 1 and those with DTPA 40% or less were assigned to group 2. After surgery followup patients with DTPA greater than 40% were designated the well preserved group and those with DTPA 40% or less were assigned to the poorly preserved group. Statistical analyses were performed to determine the best predictive variable for treatment.

RESULTS

Mean initial DTPA split renal function values of groups 1 and 2 were 47.3% and 28.8%, respectively and subsequently, they were 48.4% and 35.3%. Initial DTPA on the obstructed side of less than 35% had a 100% sensitivity and 100% positive predictive rate for a poorly preserved renal outcome. Among the various tubular functions, only percent fractional excretion of sodium and percent fractional excretion of chloride correlated with post-pyeloplasty DTPA. Urinary epidermal growth factor/creatinine correlated with preservation of renal function on postoperative DTPA renal scans. Although urinary transforming growth factor/creatinine levels and apoptosis ratios were higher on the obstructed side, they were not significantly different between the groups.

CONCLUSIONS

Proximal tubular dysfunction, such as increased percent fractional excretion of sodium and chloride, and initial DTPA 35% or less, suggest a high possibility of poorly preserved renal outcome. Urinary transforming growth factor-beta1 and apoptosis are not correlated with renal outcome. A high urinary level of epidermal growth factor might be a potential indicator of preservation of renal growth.

Alterations in the molecular determinants of bladder compliance at hydrostatic pressures less than 40 cm. H2O

PURPOSE

Bladder outlet obstruction with intravesical pressures exceeding 40 cm. H2O often results in irreversible renal damage. Bladder outlet obstruction also results in alterations in bladder physiology, including wall thickening, reduced compliance and decreased capacity. If unchecked these changes may lead to the subsequent need for bladder augmentation. From a biomechanical standpoint, compliance is primarily related to extracellular matrix deposition, which in turn is dependent on the balanced activity of proteolytic enzymes (that is matrix metalloproteinases [MMPs]) and their endogenous inhibitors (that is tissue inhibitors of metalloproteinases [TIMPs]). To date, the threshold pressure above which alterations in these key determinants of bladder compliance occur has not been determined. Therefore, using a novel device of our own design, we applied hydrostatic pressures in the physiological range to human bladder smooth muscle cells to determine the effect on MMPs, TIMP-1 and transcription of the major structural collagens (types I and III).

MATERIALS AND METHODS

Human bladder smooth muscle cells (staining positive for alpha-smooth muscle actin) were plated at a density of 100,000 cells per 10 cm.2 and cultured for 2 days in Dulbecco's modified Eagle's medium (DMEM) with 10% fetal bovine serum. Cells were subsequently exposed to pressures of 0.3, 20 and 40 cm. H2O for 1, 3, 7 and 24 hours in serum-free DMEM. A computer interface maintained pressure levels for the duration of the experiments and collected pressure data. MMP-1 and 3, and TIMP-1 immunoassay and zymography for MMP-2 and 9 were performed. Polymerase chain reaction for human collagen types I and III was performed following reverse transcription of total purified mRNA. All experiments were repeated 3 times and statistical analysis was performed using a 2-tailed Student t test.

RESULTS

Exposure of bladder smooth muscle cells to a sustained hydrostatic pressure of 20 cm. H2O for 7 hours in serum-free DMEM resulted in a time dependent decrease in MMP-1, 2 and 9 activity (15%, 37% and 25%) compared to controls maintained at atmospheric pressure (p <0.01). TIMP-1 levels increased an average of 10% after exposure to 20 cm. H2O. These changes became statistically significant when the cells were exposed to 40 cm. H2O pressure for 3, 7 and 24 hours (+14%, +21% and +50%, respectively). No statistically significant differences in MMP-3 and collagen type I or III mRNA levels were observed.

CONCLUSIONS

Our results reveal that MMP-1, 2 and 9 are significantly down-regulated in a time and pressure dependent fashion following exposure of bladder smooth muscle cells to 20 cm. H2O for as little as 7 hours. TIMP-1 levels increased under similar conditions. These alterations in MMPs and TIMP-1 favor accumulation of extracellular matrix, structural components associated with bladder wall thickness and decreased compliance. These results are consistent with previous data from animal models of complete outlet obstruction. Our results support the concept that pressures 40 cm. H2O or less contribute to molecular changes consistent with decreased compliance associated with bladder dysfunction.

Prenatal diagnosis and management of abnormalities in the urologic system

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

Cyclic stretch activates p38 SAPK2-, ErbB2-, and AT1-dependent signaling in bladder smooth muscle cells

Cyclic mechanical stretch of bladder smooth muscle cells (SMC) increases rates of DNA synthesis and stimulates transcription of the gene for heparin-binding epidermal growth factor-like growth factor (HB-EGF), an ErbB1/EGF receptor ligand that has been linked to hypertrophic bladder growth. In this study we sought to clarify the signaling pathways responsible for mechanotransduction of the stretch stimulus. HB-EGF mRNA levels, DNA synthesis, and AP-1/Ets DNA binding activities were induced by repetitive stretch of primary culture rat bladder SMC. Inhibitors of the p38 SAPK2 pathway, the angiotensin receptor type 1 (AT1), and the ErbB2 tyrosine kinase reduced each of these activities, while an inhibitor of the extracellular signal-regulated kinase mitogen-activated protein kinase (Erk-MAPK) pathway had no effect. Stretch rapidly activated stress-activated protein kinase 2 (p38 SAPK2) and Jun NH(2)-terminal kinase (JNK)/SAPK pathways but not the Erk-MAPK pathway and induced ErbB2 but not ErbB1 phosphorylation. Angiotensin II (ANG II) a bladder SMC mitogen previously linked to the stretch response, did not activate ErbB2, and ErbB2 activation occurred in response to stretch in the presence of an ANG receptor inhibitor, indicating that activation of the AT1-mediated pathway and the ErbB2-dependent pathway occurs by independent mechanisms. p38 SAPK2 and JNK/SAPK signaling also appeared to be independent of the ErbB2 and AT1 pathways. These findings indicate that stretch-stimulated DNA synthesis and gene expression in normal bladder SMC occur via multiple independent receptor systems (e.g., AT1 and ErbB2) and at least one MAPK pathway (p38 SAPK2). Further, we show that the Erk-MAPK pathway, which in most systems is linked to receptor-dependent cell growth responses, is not involved in progression to DNA synthesis or in the response of the HB-EGF gene to mechanical forces.