Urodynamic testing in the diagnosis of small animal micturition disorders

A canine model of reversible urethral sphincter insufficiency

This study developed an animal model with internal and external urethral sphincter insufficiency by bypassing the sphincter without major damage so that the animal under study can return to normal life after the study. There is a need for a reliable, applicable, and reproducible animal model for studying urinary incontinency disease due to incorrect sphincter function. Seven adult male dogs were used for this study. The urethral sphincter was bypassed by inserting a catheter between the bladder neck and the distal sphincter. The animals' physical condition was closely monitored for 9 weeks, and standard urodynamic and radiologic studies were performed before and 1-2 months after surgery. The animals were killed at 9 weeks after surgery for pathological assessment. Catheter placement caused complete incontinence in the animal, with urodynamic assessments indicating that the animal was unable to control urination and radiological assessments indicating an empty bladder with a residual volume of 50 ± 10 cc. Tissue analysis did not show significant histological damage and inflammation. The study shows that by bypassing the urethral sphincter, which is a reliable and reproducible method, an animal model of urinary incontinence can be developed, which can be used in various studies such as assessing the adequacy of artificial sphincter function. The animals under study did not have any permanent defect, so they were able to return to their normal life.

A comprehensive visual report of urodynamic study in rats with spinal cord injury

Objectives

Spinal cord injury (SCI) is one of the most debilitating and expensive traumatic conditions. Chronic complications after SCI have a particularly negative impact on patients' functional independence and quality of life. Urodynamic study (UDS) provides a quantitative assessment of lower urinary tract function in these patients. In many fields, animal models are considered a precursor to clinical trials, so research using laboratory animals play a major role in knowledge acquisition.

Materials and methods

Twelve female Wistar rats (13 weeks old, 220-270 g) were divided randomly into 2 groups: sham or SCI. The sham-operated group underwent a laminectomy at T9-T10 without any spinal cord damage, while the SCI group underwent a complete transection at the T9-T10 vertebral level. We performed cystometry in all animals at the end of the fourth week. In this article, we visualize all procedures for catheter implementation and UDS in animals for the first time at Tabriz University of Medical Sciences, Iran, using a locally developed animal UDS device.

Results

The UDS results showed that the bladders in the SCI group were overactive and that peak and baseline pressures increased significantly in rats with SCI when compared with the sham group (p < 0.05 for all). Conversely, significant reductions in bladder compliance and intercontraction interval were observed in the SCI group (p < 0.05 for both).

Conclusions

This comprehensive visual report will be very useful to all researchers in the field of urology. Furthermore, the measurable variables of the UDS device have been described in this study.

An international survey on canine urinary incontinence: case frequency, diagnosis, treatment and follow-up

Introduction

Urinary incontinence (UI) consists of involuntary leakage of urine during the storage phase of urination.

Methods

An anonymous survey was given to Spanish and Italian veterinarians about canine UI treated cases, diagnosis, treatment, follow-up, and professional interest.

Results and discussion

Most veterinarians treated ≤3 cases/quarter, resulting in the percentage of incontinence males being lower than that of females (1-4% vs 0-24%). The percentage of spayed incontinent females was lower in Spain (0-24%) than in Italy (75-100%). Most diagnoses were based on a diagnostic algorithm (Spain: 88.7%; Italy: 65.3%); patient report and history, blood work, urinalysis and abdominal ultrasound. Urethral/bladder pressure measurement was unusual (Spain: 0.2%; Italy: 2.4%). In Spain, radiology with contrast medium and CT urography (26.3% and 34.4%, respectively) were more frequent than in Italy (11.6% and 22.7%, respectively). When suspecting urethral sphincter mechanism incompetence pharmacological trial (Spain: 93.2%; Italy: 78.9%). The first-choice medical treatment was Phenylpropanolamine, followed by Ephedrine and Deslorelin. When pharmacotherapy failed, the most frequent option was drug change, followed by increased drug dosage/frequency of administration, surgical therapy and colposuspension. A review was completed after the first week of treatment followed by periodic reviews. Most of the respondents participated in continuing education only if UI occurred in their everyday practice (Spain: 63.0%; Italy: 55.4%) and about 30% responders did it regardless of the number of UI cases treated (Spain: 30.5%; Italy: 37.4%).

Conclusion

Some recommendations in clinical practice were made. UI can be underestimated by owners; therefore, a complete history should be obtained by veterinarians. Veterinarians should carefully evaluate if spaying is advisable considering it could increase UI risk. A step-by-step approach is recommended and a specific diagnostic-therapeutic algorithm for UI in dogs is provided. Conservative approaches (regular exercise, weight loss in overweight dogs and observing an "incontinence diary" to identify abnormal patterns of urination) are advisable.

ACVIM consensus statement on diagnosis and management of urinary incontinence in dogs

Urinary incontinence (UI) is a disorder of micturition that can occur in dogs of any age, sex, and breed depending on the underlying cause and time of onset. Diagnosis and treatment for various causes of UI in dogs have been described by multiple comprehensive single author review articles, but large prospective clinical trials comparing treatment outcomes in veterinary medicine are lacking. The objectives of this consensus statement therefore are to provide guidelines on both recommended diagnostic testing and treatment for various causes of UI in dogs. Specifically, pathophysiology directly related to the canine urinary system will be reviewed and diagnostic and therapeutic challenges will be addressed. A panel of 12 experts in the field (8 small animal internists [L. Adams, J. Bartges, A. Berent, J. Byron, J. Foster, A. Kendall, S. Vaden, J. Westropp], 2 neurologists [J. Coates, N. Olby], 1 radiologist [G. Oetelaar], and 1 surgeon [C. Adin]) was formed to assess and summarize evidence in the peer-reviewed literature and to complement it with consensus recommendations using the Delphi method. Some statements were not voted on by all panelists. This consensus statement aims to provide guidance for management of both male and female dogs with underlying storage or voiding disorders resulting in UI.

Idiopathic functional urinary outflow tract obstruction in dogs, a retrospective case series (2010-2021): 31 cases

BACKGROUND

Idiopathic functional urinary outflow tract obstruction (iFUOTO) is an uncommon but life-limiting disease whose etiology and clinical course of disease remain poorly understood.

OBJECTIVE

Characterize signalment, clinical signs, clinicopathologic findings, treatments, and propose a standardized response score for dogs with iFUOTO.

ANIMALS

Thirty-one client-owned dogs diagnosed with iFUOTO.

METHODS

Retrospective case series. Medical records from 2010 to 2021 were reviewed and findings recorded. Dogs were categorized based on the presence or absence of overt signs of neurological disease. Response to treatment was scored.

RESULTS

Thirty-one dogs were included. All dogs had stranguria and 14 (45%) had overflow urinary incontinence. Mean age of onset for signs was 6.9 years±8 months. Twenty-four dogs (77%) were castrated males, 5 (16%) intact males, and 2 (6%) spayed females. Eight (26%) of dogs had overt neurological deficits. Follow-up data were available for 29 dogs (median 38 days, range: 2-1277). Final outcome scores were not significantly different among dogs with overt signs of neurological disease (median score 2.5; range: 0-3) and those without (median score 1; range; 0-3; P = .35). Treatments included alpha antagonists, skeletal muscle relaxants, parasympathomimetics, anti-inflammatories, castration, temporary placement of a urethral catheter, or a combination of these.

CONCLUSIONS AND CLINICAL RELEVANCE

Multimodal treatment was frequently prescribed, but a standard outcome score is needed to evaluate the effectiveness of these therapies. Serial neurological examinations and monitoring of the dogs' dysuria are warranted.

Urodynamic and morphometric characteristics of the lower urogenital tract of male Beagle littermates from four months to two years of age

OBJECTIVE

To describe functional and anatomic changes of the lower urogenital tract of healthy male dogs during the sexually immature period and up to 2 years of age by urodynamic and morphometric assessment.

ANIMALS

6 sexually intact male Beagle littermates.

PROCEDURES

Dogs underwent electromyography-coupled urodynamic tests, CT-assisted retrograde urethrography, prostatic washes, and blood sampling monthly from 4 through 12 months of age and then at 3-month intervals. Urodynamic and morphometric variables and serum canine prostate-specific esterase concentrations were analyzed by statistical methods.

RESULTS

Integrated pressure of the urethra was significantly increased beginning at 8 months of age, compared with earlier time points. Urethral pressure peak amplitudes varied among anatomic regions. During bladder filling, few electromyographic signals were concurrent with urethral pressure peaks; these were most commonly detected in the penile portion of the urethra. Urethral length and prostate gland volume were significantly greater from 7 to 24 months of age than at younger ages. Urethral length was approximately 26 to 27 cm after 9 months, and prostate gland volume was approximately 11 to 12 cm³ after 11 months of age. Serum canine prostate-specific esterase concentrations correlated with prostate gland volume. Urinary bladder threshold volume was significantly increased at 6 months of age, compared with that at 4 months, with a maximum of 197.7 mL at 24 months.

CONCLUSIONS AND CLINICAL RELEVANCE

Urethral resistance was acquired at approximately 8 months of age, when growth of the lower urinary tract was incomplete. Electromyographic and integrated pressure measurement results and the distribution and amplitude of urethral pressure peaks highlighted the potential role of the prostate gland and possibly the bulbocavernosus muscles in control of continence.

Clinical assessment of testosterone analogues for urethral sphincter mechanism incompetence in ten spayed female dogs

Urethral sphincter mechanism incompetence (USMI) is a common cause of urinary incontinence in dogs. Although estrogen is often prescribed for the medical therapy of USMI for spayed female dogs, they are known to have limited effectiveness and potential adverse effects. In castrated male dogs with USMI, testosterone reagents have been attempted besides estrogen. In this study, the effect of testosterone drugs, mainly methyltestosterone, on spayed female dogs with USMI was retrospectively evaluated. Ten spayed female dogs with USMI were included. Diagnosis of USMI was based on the results of the dogs’ medical history, clinical signs, and no abnormalities in physical examinations, urinalysis, ultrasonography, X-ray imaging, and neurological examinations. Methyltestosterone was administered at doses of 0.32–1.27 mg/kg BW p.o. semel in die (sid.) to twice a week. Nine of the ten dogs had good or excellent responses 2 to 4 weeks after the start of treatment. The minimum effective dose was 0.32 mg/kg/day. Although no severe adverse symptoms occurred in any dog, a mild increase in alanine aminotransferase was temporally observed at doses of 1.0 and 1.1 mg/kg/day in the two dogs. After dose reduction or withdrawal, two of eight dogs had recurrence of urinary incontinence. Resumption of testosterone treatment clearly improved the symptoms in the two dogs. These results indicate that testosterone reagents might be an option for treating USMI in spayed female dogs as well.

Bladder and Bowel Management in Dogs With Spinal Cord Injury

Spinal cord injury in companion dogs can lead to urinary and fecal incontinence or retention, depending on the severity, and localization of the lesion along the canine nervous system. The bladder and gastrointestinal dysfunction caused by lesions of the autonomic system can be difficult to recognize, interpret and are easily overlooked. Nevertheless, it is crucial to maintain a high degree of awareness of the impact of micturition and defecation disturbances on the animal's condition, welfare and on the owner. The management of these disabilities is all the more challenging that the autonomic nervous system physiology is a complex topic. In this review, we propose to briefly remind the reader the physiology of micturition and defecation in dogs. We then present the bladder and gastrointestinal clinical signs associated with sacral lesions (i.e., the L7-S3 spinal cord segments and nerves) and supra-sacral lesions (i.e., cranial to the L7 spinal cord segment), largely in the context of intervertebral disc herniation. We summarize what is known about the natural recovery of urinary and fecal continence in dogs after spinal cord injury. In particular we review the incidence of urinary tract infection after injury. We finally explore the past and recent literature describing management of urinary and fecal dysfunction in the acute and chronic phase of spinal cord injury. This comprises medical therapies but importantly a number of surgical options, some known for decades such as sacral nerve stimulation, that might spark some interest in the field of spinal cord injury in companion dogs.

Anesthetic agents affect urodynamic parameters and anesthetic depth at doses necessary to facilitate preclinical testing in felines

Urodynamic studies, used to understand bladder function, diagnose bladder disease, and develop treatments for dysfunctions, are ideally performed with awake subjects. However, in small and medium-sized animal models, anesthesia is often required for these procedures and can be a research confounder. This study compared the effects of select survival agents (dexmedetomidine, alfaxalone, and propofol) on urodynamic (Δpressure, bladder capacity, bladder compliance, non-voiding contractions, bladder pressure slopes) and anesthetic (change in heart rate [∆HR], average heart rate [HR], reflexes, induction/recovery times) parameters in repeated cystometrograms across five adult male cats. The urodynamic parameters under isoflurane and α-chloralose were also examined in terminal procedures for four cats. Δpressure was greatest with propofol, bladder capacity was highest with α-chloralose, non-voiding contractions were greatest with α-chloralose. Propofol and dexmedetomidine had the highest bladder pressure slopes during the initial and final portions of the cystometrograms respectively. Cats progressed to a deeper plane of anesthesia (lower HR, smaller ΔHR, decreased reflexes) under dexmedetomidine, compared to propofol and alfaxalone. Time to induction was shortest with propofol, and time to recovery was shortest with dexmedetomidine. These agent-specific differences in urodynamic and anesthetic parameters in cats will facilitate appropriate study-specific anesthetic choices.

Canine Incontinence

Incontinence is a frustrating condition for both pet owners and their veterinarians. Fortunately, most causes are easily diagnosed and most dogs respond to appropriate therapy. This article reviews normal urine storage and voiding, causes of incontinence, typical clinical presentation, diagnostics, and treatment.

Canine urethral sphincter pressure profile under incremental inflation of an artificial cuff: a cadaver study

OBJECTIVES

To determine whether artificial urethral sphincter filling volume is proportional to peak pressure exerted on the urethra.

MATERIALS AND METHODS

Urethral pressure profilometry was performed in five female, medium-sized, mixed-breed canine cadavers following artificial urethral sphincter placement. Maximum urethral pressure was recorded following sequential incremental inflation of 0.15 mL and compared to baseline pressure and between dogs using two-way analysis of variance.

RESULTS

Artificial urethral sphincter placement in cadavers was associated with an increase in urethral pressure, which was significantly correlated with inflation volume. The correlation was non-linear and demonstrated considerable individual variation. Maximum urethral pressures after artificial urethral sphincter placement exceeded those reported in conscious continent dogs within a narrow volume range, in which a 0.15 mL infusion more than doubled maximal urethral pressures.

CLINICAL SIGNIFICANCE

Rapid increases in urethral pressure from the artificial urethral sphincter over a small range of filling volumes (0.15 mL increments) might explain why some clinical cases can become suddenly dysuric following incremental inflations. We suggest that smaller increments of filling (0.05 to 0.1 mL) may achieve finer pressure control.

Urethral Sphincter Mechanism Incompetence in Dogs: An Update

Urethral sphincter mechanism incompetence (USMI) is the most common cause of acquired urinary incontinence in dogs. The pathogenesis of USMI is multifactorial and complex. Studies have shown variable results regarding the effects and timing of sterilization on the incidence of USMI. Diagnosis of USMI is often based on history, physical examination, and elimination of other differentials. Treatment options for USMI include medications, such as α-adrenergic agents and estrogen products, minimally-invasive urethral bulking procedures, surgical procedures (e.g., indwelling urethral occluders), or combination therapy. The overall prognosis for USMI is typically fair to good with long-term therapy.

Urodynamic characteristics of rats with detrusor instability

The purpose of the present study is to investigate urodynamic characteristics of rats with detrusor instability (DI) induced by different causes. Forty-eight adult female Sprague-Dawly rats were randomly divided into 4 groups: cyclophosphamide group, bladder outlet obstruction group, lipopolysaccharide group and control group. The BL-410 model bio-function experimental system was applied to monitor bladder pressure and a number of urodynamic parameters were recorded and calculated, including the frequency of detrusor instability, maximum voiding pressure (MVP), maximum cystometric capacity (MCC), intercontraction interval (ICI), voiding time (VT), postvoid residual (PVR) and bladder compliance (BC). The positive rates of DI in cyclophosphamide group, bladder outlet obstruction group and lipopolysaccharide group were 83.33%, 75.00% and 58.33%, respectively. And correspondingly the frequency of DI was 10.00±2.00, 4.87±1.24 and 3.50±1.00tmin(-1), which was significantly higher than those of the control group (P<0.05). Compared with the control group, the decrease of MVP, MCC, ICI, VT and BC was noted in the cyclophosphamide group and lipopolysaccharide group. Increased PVR, MVP, MCC, VT and BC were presented in the bladder outlet obstruction group. Therefore, we suggested that the urodynamic parameters could reflect the pathophysiological characteristics of DI induced by different causes, which could systematically benefit the diagnosis and treatment of overactive bladder.

Urodynamic investigation by telemetry in Beagle dogs: validation and effects of oral administration of current urological drugs: a pilot study

Background

Vesico-urethral function may be evaluated in humans and dogs by conventional urodynamic testing (cystometry and urethral pressure profilometry) or by electromyography. These techniques are performed under general anaesthesia in dogs. However, anaesthesia can depress bladder and urethral pressures and inhibit the micturition reflex. The primary objective of this pilot study was to evaluate the use of telemetry for urodynamic investigation in dogs. We also aimed to determine the applicability of telemetry to toxicologic studies by assessing the repeatability of telemetric recordings.

Results

Conventional diuresis cystometry was performed in six continent adult female Beagle dogs prior to surgical implantation of telemetric and electromyographic devices. In the first phase of the telemetric study, continuous recordings were performed over 8 days and nights. Abdominal, intravesical and detrusor threshold pressures (Pdet th), voided volume (Vv), urethral smooth muscle electrical activity and involuntary detrusor contractions (IDC) were measured during the bladder filling phase and during micturition episodes.

Vv recorded during telemetry was significantly lower than bladder volume obtained by diuresis cystometry. Repeatability of telemetric measurements was greater for observations recorded at night. IDC frequency and Pdet th were both lower and Vv was higher at night compared to values recorded during daytime.

In the second phase of the telemetric study, phenylpropanolamine, oestriol, bethanechol, oxybutynin or duloxetine were administered orally for 15 days. For each drug, continuous recordings were performed overnight for 12 hours on days 0, 1, 8 and 15. Electromyographic urethral activity was significantly increased 8 days after oestriol or duloxetine administration. No significant changes in bladder function were observed at any time point.

Conclusions

In dogs, the high repeatability of nocturnal telemetric recordings indicates that this technique could provide more informative results for urologic research. Urethral smooth muscle electrical activity appears to be modified by administration of drugs with urethral tropism. In this pilot telemetric study, bladder function was not affected by oral administration of urological drugs at their recommended clinical dosages. Experimental studies, (pharmacokinetic and pharmacodynamic) and clinical studies are warranted to further define the effects of these drugs on vesico-urethral function in dogs.

Urodynamic and morphometric characteristics of the lower urogenital tracts of female Beagle littermates during the sexually immature period and first and second estrous cycles

OBJECTIVE

To compare values of lower urogenital tract urodynamic and morphometric variables determined during the prepubertal (sexually immature) period and first and second estrous cycles in healthy female Beagle littermates to determine functional and anatomic changes of the lower urogenital tract during those periods.

ANIMALS

5 female Beagle littermates.

PROCEDURES

Urethral pressure profilometry, diuresis cystometry, and vaginourethrography were performed when dogs were 3.5, 4.5, 5, 6, 7, 8, 8.5, and 9 months old and during proestrus; estrus; early, middle, and late diestrus; and early and late anestrus of the first and second estrous cycles.

RESULTS

At the end of the prepubertal period, values of urodynamic and morphometric variables increased significantly, compared with values at earlier times. Maximum bladder capacity developed when dogs were 9 months old. In all dogs, the bladder was intermittently located in an intrapelvic position during the prepubertal period; the bladder was intra-abdominal from the time dogs were 9 months old until the end of the study. Urethral pressure decreased significantly during estrus and early diestrus of the first and second estrous cycles. Bladder capacity increased significantly during diestrus of both estrous cycles. Urethral and vaginal lengths were significantly longer during proestrus and estrus than they were during anestrus.

CONCLUSIONS AND CLINICAL RELEVANCE

Values of lower urogenital tract urodynamic and morphometric variables were influenced by age and phases of the estrous cycle of immature and young adult Beagles in this study. Age of dog and phase of estrous cycle should be considered when interpreting urodynamic and vaginourethrography data.

Designing clinical trials in canine spinal cord injury as a model to translate successful laboratory interventions into clinical practice

Many interventions have been shown to improve outcome after experimental spinal cord injury in laboratory animals. The challenge now is to determine whether any of these can be translated to become an efficacious therapy for clinical lesions - a process that is often difficult and frequently fails. Here, we discuss the steps that are required to make this transition and the need for rigorous clinical trials. A key component is an outcome measure that is amenable to statistical analysis; we describe methods that we have developed to accurately measure function after spinal cord injury in dogs. The general methodology may have parallels in the development of veterinary models to test putative therapies for other diseases of humans and animals.

Therapeutic efficacy of botulinum toxin in the treatment of urinary incontinence in female dogs

Urinary incontinence in animals poses a growing therapeutic problem. Satisfactory results in the treatment of incontinence are not reported despite the wide availability of pharmaceuticals addressing the problem. The growing number of side effects and the need for sustained pharmacotherapy have prompted a search for new treatment methods. The experiment described in this study was performed on 11 bitches with clinical symptoms of urinary incontinence. The dogs underwent cystoscopy during which botulinum toxin solution was injected into the wall of the urinary bladder (50-100 botulinum toxin units were given per animal in 10 injections), causing changes in its innervation. Positive therapeutic effects lasting for 5 months in average were noted in 70% of the treated animals.

Use of a rigid endoscope to teach urethral catheterization of the female dog

Urethral catheterization of the female dog is known to be a challenging procedure. The authors describe a catheterization technique in which they use a rigid endoscope to visualize the canine urogenital vestibule during the procedure. The technique is particularly helpful as a training tool for students who are not yet experienced with the canine anatomy. The endoscope is attached to a video camera and monitor, allowing others to observe and learn the procedure.

Comparison of two experimental models of urodynamic evaluation in female rats

PURPOSE

Urodynamic studies in small animals can be performed through urethral sounding or cystostomy.

OBJECTIVE

To compare the two methods of urodynamic evaluation in female rats.

METHODS

Ten female rats weighing on average 250 g, under anesthesia with urethane (1.25 mg/kg) were submitted in three repeats to an urethal catheter of 0,64 mm in external diameter for cystometric measurements of vesicle pressure(VP1) and contraction time (CT1). The catheter was extracted at a constant velocity of 0.05 cm/minute until complete exteriorization and determinations of maximal urethral pressure (UP1) and functional urethral length (FUL1). This was followed by a cystostomy with catheter PE50 and a new determination of the vesical pressure (VP2). After bladder denervation, a new cystometric record indirectly infered the maximum urethral closure pressure (UP2). The peak urethal pressure (UP3) and the functional urethral length (FUL2) were determined in another urethral sounding. The pressure registration system consisted of a continuous infusion pump regulated to a flow of 0.1 ml/minute connected both to the cystostomy catheter (PE-50) or the urethal catheter (0.64 mm) and the polygraph Narco-Biosystem. Statistical analysis employed the Wilcoxon non-parametric test

RESULTS

Mean VP1= 48.2 mmHg (11,8 SD); Mean VP2 = 38.2 mmHg (9.0 SD) "p" (VP1 X VP2) = 0.0039. Mean CT1=30.2 s (21.5 SD); Mean CT2=20.0 s(7 SD) p (CT1 X CT2) = 1.28. Mean UP1 = 47.2 mmHg (6.5 SD); Mean UP2 = 21.3 mmHg (6.6 SD), mean UP3 = 40.7 mmHg(13.3 SD) p (UP1 X UP2) = 0.002; "p" (UP1 X UP3) = 0.084; p (UP2 X UP3) = 0.002. Mean FUL1=14.2 mm (1.9 SD); Mean FUL2= 14.1 mm (1.9 SD); p (FUL1 X FUL2) = 0.64.

CONCLUSIONS

The methods employed to evaluate vesical and urethral pressures are different. The presence of the urethral catheter may be an obstructive factor. Surgical denervation up to the bladder neck level does not compromise urethral function.

A canine model of irreversible urethral sphincter insufficiency

OBJECTIVE

To develop a canine model of external urinary sphincter insufficiency by creating irreversible damage to the sphincter, because there is a need for a reliable and reproducible large animal model for the study of stress urinary incontinence (SUI) caused by deficient sphincter function.

MATERIALS AND METHODS

About a quarter of the total external sphincter muscle was removed microsurgically from seven female dogs; three age-matched dogs served as normal controls. The dogs had standard urodynamic and radiographic studies before and at 1, 2, 3, 4 and 7 months after surgery. Three dogs were killed at 4 months and four at 7 months after surgery for tissue analyses.

RESULTS

The interventions produced a consistent outcome. Urodynamic studies showed a significant and sustained decrease in sphincter function, which included a static urethral pressure profile, stress urethral profile and detrusor leak-point pressure. Furthermore, in vivo pudendal nerve stimulation and organ-bath studies of the retrieved tissue strips confirmed the loss of sphincter tissue function. Histologically, absence of functional sphincter muscle was evident in the damaged sphincter region.

CONCLUSIONS

These results show that a reliable and reproducible canine model of irreversible sphincter insufficiency can be created by microsurgical removal of sphincter muscle tissue. This model of external sphincter insufficiency could be used for evaluating methods (e.g. cell therapies) for treating SUI.

Bladder wall replacement by tissue engineering and autologous keratinocytes in minipigs

OBJECTIVE

To develop a tissue-engineered bladder wall replacement with autologous cells and a biodegradable scaffold, as whenever there is a lack of native urological tissue the bladder is reconstructed with different bowel segments, which has inevitable complications.

MATERIAL AND METHODS

Skin biopsies were taken from six minipigs, and primary fibroblast and keratinocyte cell cultures established. A partial resection of the urinary bladder was reconstructed by a cell-seeded scaffold covered with completely differentiated epithelium and supported by a mucosa-free pedicled ileum graft. Each pig was assessed urodynamically and by cystography before operation and every month until explantation; the pigs were killed at 1, 2 and 3 months after augmentation. Control groups (of six pigs each) with bladder augmentation with complete or denuded ileum were used. The bladders were assessed histologically and by distensibility measurements

RESULTS

The differentiated keratinocyte epithelium was still present on the reconstructed bladder wall after 3 months. The overall shrinkage rate was 6.5%. The engineered bladder wall had lower distensibility than the native one. The inflammatory reaction present initially had disappeared after 3 months.

CONCLUSIONS

The implanted, tissue-engineered substitution of the bladder wall is not only a bridging graft, but also a complete reconstruction. With this model, extended bladder wall substitution seems feasible and should be investigated in further studies.