Effects of posterior urethral valves on long-term bladder and sexual function

Clinical considerations in adults with history of posterior urethral valves

INTRODUCTION

Management of patients with posterior urethral valves (PUV) is commonplace for many pediatric urologists, however adult providers may be far less familiar with this diagnosis, its management and long-term ramifications. As urologic management of these patients has evolved, clinical outcomes have substantially improved with many more patients now surviving into adulthood. These patients remain at increased risk of morbidity due to their condition and therefore are likely to benefit from long term follow-up with adult providers.

OBJECTIVE

In this review we analyze the psychosocial impacts of PUV on adults, evaluate long term transplant outcomes in PUV patients and discuss effective clinical management strategies of bladder dysfunction in adult PUV patients.

STUDY DESIGN

A retrospective literature review was performed using the MEDLINE (Pubmed) electronic database using key words such as "posterior urethral valve", "quality of life", "sexual function", "transplant outcomes", "bladder dysfunction", "mitrofanoff" etc. to identify relevant studies.

RESULTS

Generally, the quality of life of PUV patients is good, those suffering from renal insufficiency or lower urinary tract symptoms, specifically incontinence, appear to be a group that may benefit from more intensive follow-up. Good long-term kidney transplant (KT) function and survival can be achieved in patients with PUV. Rigorous management to optimize bladder function and close follow-up, are key for long term graft survival after KT.

DISCUSSION

The chronicity of PUV warrants adult providers to be not only well versed in the pathophysiology of the disease, but well prepared to care for these patients as they transition into adulthood.

CONCLUSION

Additional studies addressing psychosocial, clinical and transplant outcomes of adults with PUV are necessary to develop optimal long-term follow-up regimens for these patients.

A grading system for evaluation of bladder trabeculation

PURPOSE

To establish a parameter-based grading system for evaluating bladder trabeculation (BT).

MATERIALS AND METHODS

A retrospective analysis was conducted on children diagnosed with posterior urethral valve (PUV) or neurogenic bladder (NB) who underwent voiding cystourethrogram (VCUG), urodynamic testing, and urological ultrasonography between January 2016 and October 2022. Cases involving urologic surgery, secondary bladder pathology, and an interval of more than 12 months between examinations were excluded. A parameter named Bladder Dispersion (BD) was calculated through fluoroscopic images, and the grading system was developed as follows: BD < 40 (Grade 0), 40 ≤ BD < 60 (Grade 1), 60 ≤ BD < 90 (Grade 2), BD ≥ 90 (Grade 3). Grades 0-1 were classified as low-risk group, while grades 2-3 were classified as high-risk group. Analysis of variance, Kruskal-Wallis test, and Chi-square test were performed to compare urodynamic results and complications across different grades and groups.

RESULTS

A total of 74 patients were eligible to participate, which included 46 boys (62.2%) and 28 girls (37.8%), the mean age was 75.18 ± 48.39 months. Among them, 11 (14.9%) were PUV, 50 (67.6%) were NB, and 13 (17.5%) were PUV and NB. Significant differences were observed in maximum detrusor pressure, post-void residual urine ratio, and compliance among grades 0-3. Severe hydronephrosis and histories of urinary tract infection were more prevalent in the high-risk group.

CONCLUSION

A reliable grading system with objective standards was proposed which could aid in the assessment of BT severity.

Anti-fibrotic effect of tocotrienols for bladder dysfunction due to partial bladder outlet obstruction

PURPOSE

To investigate potential beneficial effects of tocotrienols which have been suggested to inhibit hypoxia-inducible factor (HIF) pathway, on partial bladder outlet obstruction (PBOO)-induced bladder pathology.

MATERIALS AND METHODS

PBOO was surgically created in juvenile male mice. Sham-operated mice were used as controls. Animals received daily oral administration of either tocotrienols (T₃) or soybean oil (SBO, vehicle) from day 0 to 13 post-surgery. Bladder function was examined in vivo by void spot assay. At 2 weeks post-surgery, the bladders were subjected to physiological evaluation of detrusor contractility in vitro using bladder strips, histology by H&amp;E staining and collagen imaging, and gene expression analyses by quantitative PCR.

RESULTS

A significant increase in the number of small voids was observed after 1 week of PBOO compared to the control groups. At 2 weeks post-surgery, PBOO+SBO mice showed a further increase in the number of small voids, which was not observed in PBOO+T₃ group. PBOO-induced decrease in detrusor contractility was similar between two treatments. PBOO induced bladder hypertrophy to the same degree in both SBO and T₃ treatment groups, however, fibrosis in the bladder was significantly less prominent in the T₃ group than the SBO group following PBOO (1.8- vs. 3.0-fold increase in collagen content compared to the control). Enhanced levels of HIF target genes in the bladders were observed in PBOO+SBO group, but not in PBOO+T₃ group compared to the control.

CONCLUSIONS

Oral tocotrienol treatment reduced the progression of urinary frequency and bladder fibrosis by suppressing HIF pathways triggered by PBOO.

Can Concomitant Bladder Neck Incision and Primary Valve Ablation Reduce Early Re-admission Rate and Secondary Intervention?

Objective:

To assess the effect of bladder neck morphology and its incision (BNI) in patients with posterior urethral valve (PUV) on early reintervention rate.

Patients and methods:

Infants undergoing PUV ablation (PVA) before 24 months of age and had at least 18 months of follow-up, were categorized into three groups according to the bladder neck appearance on baseline radiological and endoscopic examination: group 1; normal bladder neck underwent PVA, group 2; high bladder neck underwent PVA plus BNI, group 3; high bladder neck underwent PVA only. Early reintervention was defined as the need for check cystoscopy because of persistent renal function deterioration, worsening hydronephrosis and/or unsatisfactory VCUG improvement during the 1st six months post primary PVA.

Results:

Between 2000 and 2017, a total of 114 patients underwent PVA and met the study criteria with a median follow-up of 58 (18-230) months. For group 1, 16 (22.9%) patients needed readmission. Check cystoscopy was free and no further intervention was performed in 5(7.5%) and re-ablation was performed in 11(15.7%) patients. For group 2, 3(14.3%) patients needed reintervention. Re-ablation and re-ablation plus BNI were performed in 1(4.8%) and 2(9.5%), respectively. For group 3, cystoscopy was free in 1(4.3%), re-ablation and re-ablation plus BNI were performed 2(8.7%) and 1(4.3%), respectively. There were no significant differences in the re-admission and re-intervention rates among the three study groups (p=0.65 and p=0.50, respectively).

Conclusion:

In morphologically high bladder neck associated PUV, concomitant BNI with PVA doesn’t reduce early re-intervention rate.

Posterior urethral valves: Role of prenatal diagnosis and long-term management of bladder function; a single center point of view and review of literature

Posterior Urethral Valves (PUV) are the most common cause of lower urinary tract obstruction. More severe forms are detected early in pregnancy (mainly type I), while other forms are usually discovered later in childhood when investigating lower urinary tract symptoms. Bladder dysfunction is common and is associated with urinary incontinence in about 55% (0%-72%). Despite the removal of the obstruction by urethral valve ablation, pathological changes of the urinary tract can occur with progressive bladder dysfunction, which can cause deterioration of the upper urinary tract as well. For this reason, all children with PUV require long-term follow-up, always until puberty, and in many cases life-long. Therefore, management of PUV is not only limited to obstruction relief, but prevention and treatment of bladder dysfunction, based on urodynamic observations, is paramount. During time, urodynamic patterns may change from detrusor overactivity to decreased compliance/small capacity bladder, to myogenic failure (valve bladder). In the past, an aggressive surgical approach was performed in all patients, and valve resection was considered an emergency procedure. With the development of fetal surgery, vesico-amniotic shunting has been performed as well. Due to improvements of prenatal ultrasound, the presence of PUV is usually already suspected during pregnancy, and subsequent treatment should be performed in high-volume centers, with a multidisciplinary, more conservative approach. This is considered to be more effective and safer. Primary valve ablation is performed after clinical stability and is no longer considered an emergency procedure after birth. During childhood, a multidisciplinary approach (pediatric urologist, nephrologist, urotherapist) is recommended as well in all patients, to improve toilet training, using an advanced urotherapy program with medical treatments and urodynamic evaluations. The aim of this paper is to present our single center experience over 30 years.

Bladder function in children with posterior urethral valves: impact of antenatal versus postnatal diagnosis

Purpose:

Posterior urethral valves (PUVs) are the most common cause of congenital bladder obstruction in boys. Our aim was to assess the impact of early diagnosis and fulguration of PUVs on bladder function and compare their functional and urodynamic outcome with children who underwent delayed intervention.

Materials and Methods:

We retrospectively evaluated 153 patients who underwent primary valve ablation from two tertiary hospitals between 2001 and 2018. Patients have been divided into 2 groups, group 1 included 69 patients who were detected antenatally and underwent early fulguration of PUVs while group 2 included 84 children presented postnatally and underwent delayed valve ablation. The recorded data throughout follow-up in renal function tests, urodynamics and changes in the upper urinary tracts were evaluated and compared.

Results:

Median age at time of valve ablation was 10 days in group 1 and 7 months in group 2. The median follow-up period was 6.5 and 7 years in group 1 and 2, respectively. Chronic kidney disease (CKD) developed in 15 (22%) boys in group 1 while in group 2 it was observed in 31 (37%), p=0.04. While Q-max, mean bladder capacity and post-void residual (PVR) volumes were comparable in both groups, percent PVR was significantly higher in group 2 (3.27 vs. 1.44, p=0.002). Detrusor overactivity was slightly different in both groups (p = 0.07).

Conclusions:

Compared to delayed intervention, primary ablation of PUVs during the early neonatal life possibly provides the optimum chance to have optimum renal function without impact on bladder function.

Antenatal and postnatal management of posterior urethral valves: where do we stand?

Introduction

Posterior urethral valve (PUV) is the leading etiology of lower urinary tract obstruction (LUTO) in boys and is an important cause of end-stage renal disease (ESRD) in children. The aim of this article is to review the current status on antenatal intervention for PUV as well as postnatal medical and surgical management.

Main body

MEDLINE, EMBASE, Pubmed and Google Scholar search was conducted throughout December 2020 using the keywords: posterior urethral valves, congenital urinary obstruction, antenatal, valve bladder syndrome, medical, anticholinergics, alpha blocker, antibiotics, biofeedback, diversion, augmentation cystoplasty and renal transplantation. Only papers written in English were included. The relevant literature was summarized. Despite advances in antenatal intervention for fetal LUTO, it remains associated with considerable fetal and maternal morbidity. Patient selection criteria for antenatal intervention are greatly debated. Fetal intervention has resulted in improved perinatal survival in properly selected cases, with a questionable benefit to postnatal renal function. There is decent evidence supporting the use of anticholinergics in infants and young children following valve ablation, with less robust evidence advocating alpha blockers, overnight catheter drainage and biofeedback. The role of urinary diversion remains contentious. Optimizing bladder dynamics is crucial for successful renal transplantation outcomes.

Conclusion

While antenatal intervention has failed to improve renal function outcomes of PUV, patient-centered medical and sometimes surgical interventions can help delay the progression of chronic kidney disease. Lifelong monitoring and management of the associated bladder dysfunction is indispensable even after successful renal transplantation.

The basics of transition in congenital lifelong urology

PURPOSE

Transition in urology is defined by the process that allows an adolescent or a young adult with a congenital or acquired urogenital anomaly to assume increasing responsibility for their own health care and to become the primary decision maker in their care.

METHODS

A review of the literature regarding transitional care for lifelong urologic congenital anomalies was performed with the aim of reporting expert opinion when data are non-existent. This review focuses on special considerations for adolescents and young adults with spina bifida, bladder exstrophy, anorectal malformations and differences of sexual development.

RESULTS

Urologic goals during the transition from childhood to adulthood continue to include attention to the preservation of renal function and optimization of lower urinary tract function. Additional concerns include care to decrease long-term surgical complications (especially after augmentation cystoplasty), to monitor for malignancy, to prepare for sex activity and fertility, and to help the adult patient in decision making. Transition aims to maximize quality of life and independence by ensuring uninterrupted appropriate care through a multidisciplinary approach which varies by geographical location and healthcare setting. Barriers include patient and family factors as well as provider and system related factors. A dedicated team is an important element of successful transition.

Long-term outcome of pediatric renal transplantation in boys with posterior urethral valves

PURPOSE

To determine whether there is a difference in the outcome of renal transplantation (RT) in patients with posterior urethral valves (PUV) and children with non-uropathy related end stage renal disease.

METHODS

Data were acquired retrospectively. We analyzed possible factors that influence the function of renal allografts and graft survival. Between 1995 and 2016 there were 149 RT. Out of them, there were 27 boys with PUV, who received 29 kidneys. Thirty patients, who received a total of 31 renal grafts due to a non-uropathic (NU) diagnosis, served as control group. Mean follow-up was 7.4 to 10.2 years.

RESULTS

There was no difference in estimated graft survival between patients with PUV and NU patients. Graft failure occurred in 23.1% of PUV patients and 34.5% patients of the NU group. There was no statistically significant disparity in graft function between the two groups. Age at transplantation and donor age were the only factors that had a significant impact on renal function. There was a higher incidence of UTI in the PUV group (96%) than in the NU group (67%). Vesicostomy was the favourable intervention in regards of graft function.

CONCLUSIONS

RT in PUV patients is successful with the same outcome as in NU patients. Bladder dysfunction may not have a major impact on graft function and graft survival. It seems that the type of pre-transplant surgical procedures may influence outcome. Therefore, these interventions -if necessary- should be limited to a minimum.

TYPE OF STUDY

Retrospective Comparative Study LEVEL OF EVIDENCE: Level III.

Can bladder fibrosis in congenital urinary tract obstruction be reversed?

A variety of conditions exists in adults and children in which functional or anatomical urinary tract obstructions cause bladder fibrosis, which reduces the bladder's ability to store and empty urine. Current surgical procedures include removal of the obstructions to facilitate bladder emptying or prompt prenatal or postnatal spinal closure to prevent further neurogenic damage. Bladder fibrosis may occur, and it can get worse if a flow hindrance persists or deteriorates. Anti-fibrotic therapeutic strategies that target a variety of factors have been developed in animal models, but currently there are no anti-fibrotic therapies available for clinical use. This review examines the pathogenesis of bladder fibrosis that is caused by congenital obstructions of the lower urinary tract, and it focuses on the principal signalling factors and potential treatment modalities.

Preventative effects of a HIF inhibitor, 17-DMAG, on partial bladder outlet obstruction-induced bladder dysfunction

Posterior urethral valves are the most common cause of partial bladder outlet obstruction (PBOO) in the pediatric population. Pathological changes in the bladder developed during PBOO are responsible for long-lasting voiding dysfunction in this population despite early surgical interventions. Increasing evidence showed PBOO induces an upregulation of hypoxia-inducible factors (HIFs) and their transcriptional target genes, and they play a role in pathophysiological changes in the obstructed bladders. We hypothesized that blocking HIF pathways can prevent PBOO-induced bladder dysfunction. PBOO was surgically created by ligation of the bladder neck in male C57BL/6J mice for 2 wk. PBOO mice received intraperitoneal injection of either saline or 17-DMAG (alvespimycin, 3 mg/kg) every 48 h starting from day 1 postsurgery. Sham-operated animals received injection of saline on the same schedule as PBOO mice and served as controls. The bladders were harvested after 2 wk, and basal activity and evoked contractility of the detrusor smooth muscle (DSM) were evaluated in vitro. Bladder function was assessed in vivo by void spot assay and cystometry in conscious, unrestrained mice. Results indicated the 17-DMAG treatment preserved DSM contractility and partially prevented the development of detrusor over activity in obstructed bladders. In addition, PBOO caused a significant increase in the frequency of micturition, which was significantly reduced by 17-DMAG treatment. The 17-DMAG treatment improved urodynamic parameters, including increases in the bladder pressure at micturition and nonvoid contractions observed in PBOO mice. These results demonstrate that treatment with 17-DMAG, a HIF inhibitor, significantly alleviated PBOO-induced bladder pathology in vivo.

Cystometrogram appearance in PUV is reliably quantified by the shape,wall, reflux and diverticuli (SWRD) score, and presages the need for intervention

OBJECTIVE

Radiological bladder abnormalities in boys with posterior urethral valves (PUV) are well recognised; however, the assessment is subjective. The shape, wall, reflux and diverticuli (SWRD) score objectively assesses shape, wall, reflux and diverticuli in a simple way. This study was undertaken to demonstrate that the SWRD score is reliable, reproducible and correlates with bladder outcome and videourodynamic (VUD) assessment in boys with PUV.

MATERIALS AND METHODS

Three blinded assessors determined the SWRD scores of PUV bladders from cystometrograms taken during VUD from September 2012 to October 2013. The scores were correlated with clinical outcome and VUD pressure measurements. Data were given as median (interquartile range), non-parametric tests used as appropriate (Mann-Whitney U test, or Kruskall-Wallis) and P < 0.05 was taken as significant.

RESULTS

A total of 55 boys with PUV underwent VUD assessment, for which 52 cystometrograms were available. The SWRD score for non-operative management was 1.0 (0.1-1.9) vs 2.0 (1.0-3.3) for operative intervention, P = 0.018 (Summary Figure). The SWRD score for compliant bladders was 1.1 (0.6-2.0) vs hypercompliant 1.7 (0.5-2.8) vs non-compliant 3.3 (2.8-5.0), Kruskall-Wallis P = 0.011. The hostile detrusor overactivity (DO) bladders (Pdet >40 cmH₂O) had a SWRD score of 2.0 (1.3-3.7) vs 1.0 (0.5-2.5) for low-pressure DO bladders, P < 0.05.

DISCUSSION

In this series of patients, increasingly distorted bladder shape was seen to be associated with poor bladder dynamics on VUD. Patients with poorly compliant bladders had a significantly higher SWRD score than normal or megacystis patients. Severe DO was also significantly associated with a high SWRD score. Therefore, the radiological appearance of a hostile bladder represented a marker for high intravesical pressure. VUR and bladder diverticuli may lead to spurious pressure measurements during VUD; however, the SWRD score provided an independent mechanism with which to objectively assess these patients, even in the presence of gross VUR.

CONCLUSIONS

The SWRD score is a simple and objective scoring system for the radiological abnormalities of PUV bladders. It correlates with clinical outcome and VUD assessment of compliance and DO, but is independent of pressure measurements and so not confounded by VUR acting as a 'pop-off' mechanism.

Testosterone Modifies Alterations to Detrusor Muscle after Partial Bladder Outlet Obstruction in Juvenile Mice

Lower urinary tract symptoms secondary to posterior urethral valves (PUV) arise in boys during adolescence. The reasons for this have previously been attributed to increased urine output as boys experience increased growth. Additionally, there are few choices for clinicians to effectively treat these complications. We formed the new hypothesis that increased androgen levels at this time of childhood development could play a role at the cellular level in obstructed bladders. To test this hypothesis, we investigated the role of testosterone on bladder detrusor muscle following injury from partial bladder outlet obstruction (PO) in mice. A PO model was surgically created in juvenile male mice. A group of mice were castrated by bilateral orchiectomy at time of obstruction (CPO). Testosterone cypionate was administered to a group of castrated, obstructed mice (CPOT). Bladder function was assessed by voiding stain on paper (VSOP). Bladders were analyzed at 7 and 28 days by weight and histology. Detrusor collagen to smooth muscle ratio (Col/SM) was calculated using Masson's trichrome stain. All obstructed groups had lower max voided volumes (MVV) than sham mice at 1 day. Hormonally intact mice (PO) continued to have lower MVV at 7 and 28 days while CPO mice improved to sham levels at both time points. In accordance, PO mice had higher bladder-to-body weight ratios than CPO and sham mice demonstrating greater bladder hypertrophy. Histologically, Col/SM was lower in sham and CPO mice. When testosterone was restored in CPOT mice, MVV remained low at 7 and 28 days compared to CPO and bladder-to-body weight ratios were also greater than CPO. Histologic changes were also seen in CPOT mice with higher Col/SM than sham and CPO mice. In conclusion, our findings support a role for testosterone in the fibrotic changes that occur after obstruction in male mice. This suggests that while other changes may occur in adolescent boys that cause complication in boys with PUV, the bladder itself responds to testosterone at the cellular level. This opens the door to a new understanding of pathways that influence bladder fibrosis and could lead to novel approaches to treat boys with PUV.

Long-term Impacts of Concurrent Posterior Urethral Valve Ablation and Bladder Neck Incision on Urinary Continence and Ejaculation

OBJECTIVE

To assess the long-term impacts of bladder neck incision (BNI) on continence and ejaculatory function of adults who underwent concurrent posterior urethral valve (PUV) ablation and BNI during childhood.

MATERIALS AND METHODS

A retrospective chart review was performed to find all adult patients with relevant history. All patients had undergone BNI at 6 o'clock proximal to the verumontanum with caution to leave the adventitia and verumontanum untouched. Charts were reviewed and attempts were made to contact those ≥18 years old for follow-up. Patients were specifically evaluated for lower urinary tract symptoms and ejaculatory condition.

RESULTS

Among patients treated for PUV between 1998 and 2015 in our center, 21 were ≥18 years old at the time of assessment. Until February 2016, we were able to contact 18 patients, all of whom agreed to participate. Mean age was 21.1 ± 2.9 years with a mean follow-up of 12.5 ± 4.8 years. None of those contacted had incontinence or dry ejaculations. All considered their ejaculations normal and only one complained of weak ejaculations. Four of 5 patients who consented to perform a semen analysis had normal tests and 1 had low sperm count with abnormal motility.

CONCLUSION

BNI is not associated with additional risk of incontinence and dry ejaculation in early adulthood and preserves antegrade ejaculation. Concomitant valve ablation with BNI may provide additional benefits in care of PUV children, especially those with prominent bladder neck and poor bladder function at presentation.

Sensory function assessment of the human male lower urinary tract using current perception thresholds

AIMS

To evaluate the feasibility and reliability of current perception threshold (CPT) measurement for sensory assessment of distinct locations in the male lower urinary tract (LUT).

METHODS

Twelve male subjects (>18 years) without LUT symptoms or medical comorbidities were eligible. CPTs were determined twice (interval: 7-20 days) at the bladder dome, trigone and the proximal, membranous, and distal urethra. Square wave electrical stimulation of 3 Hz/0.2 ms and 0.5 Hz/1 ms was applied using a transurethral 8F catheter placed under fluoroscopic control. Bladder volume was kept constant (60 mL) using a second 10F catheter. Repetitive measurements and reliability were assessed by analysis of variance (ANOVA) and intraclass correlation coefficient (ICC).

RESULTS

The ANOVA revealed significant main effects for stimulation site (P = 0.008) and type of stimulation (P < 0.001) with lower CPTs for 0.5 Hz/1 ms compared to 3 Hz/0.2 ms. There was no significant effect for visit number (P = 0.061). CPTs were higher for bladder dome than for proximal (0.5 Hz/1 ms: P = 0.022; 3 Hz/0.2 ms: P = 0.022) and distal urethra (0.5 Hz/1 ms: P = 0.026; 3 Hz/0.2 ms: P = 0.030). Reliability of CPT measurements was excellent to good (ICC = 0.67-0.96) except for the bladder dome (5 Hz/1 ms: ICC = 0.45; 3 Hz/0.2 ms: ICC = 0.20) and distal urethra (3 Hz/0.2 ms: ICC = 0.57).

CONCLUSIONS

CPTs can be reliably detected at different LUT locations. However, alert and compliant subjects are essential. CPTs of LUT may become a complementary assessment method providing information on responsiveness and sensitivity of afferent LUT nerves. This is especially relevant for urethral afferents, which are not covered by standard urodynamic investigations. Neurourol. Urodynam. 36:469-473, 2017. © 2016 Wiley Periodicals, Inc.

Transitional care in pediatric urology

The transition from childhood to adolescence and into adulthood occurs as a natural component of human development. As children progress through school and gain independence, health care practitioners must facilitate a parallel transition from pediatric to adult providers. Modern medicine has succeeded in extending the life expectancy for many children with complex conditions, and adult providers are participating in their medical care through adulthood. Transitioning pediatric urology care to adult urology care is unique to every individual and his or her underlying condition, while the transition process is universal. The objectives of all pediatric urologists include preservation of the kidneys and lower urinary tracts, safe urine storage, safe urine drainage, urinary continence, fertility, sexual function, and genital cosmesis. For some children, these objectives can be attained during childhood, while other children require lifelong maintenance and management. Children with posterior urethral valves, exstrophy-epispadias complex, cloaca, vesicoureteral reflux, neurogenic bladder, disorders of sex development, cancer, hypospadias, nephrolithiasis, undescended testes, varicoceles, ureteropelvic junction obstruction, solitary kidney, and upper tract anomalies all require long-term evaluation and management. The obstacles of altering a patient and caregiver paradigm, locating adult urologists with special expertise, coordinating care with other adult specialties such as nephrology, and navigating the adult health care environment can impede the transition process.