Addressing challenges in underactive bladder: recommendations and insights from the Congress on Underactive Bladder (CURE-UAB)

How do we make progress in phenotyping patients with lower urinary tract such as overactive bladder and underactive detrusor, including using urine markers and microbiome data, to personalize therapy? ICI-RS 2023-Part 2

INTRODUCTION

Overactive bladder (OAB) and underactive bladder (UAB) could be associated with metabolic syndrome, affective disorders, sex hormone deficiency, changes in urinary microbiota, functional gastrointestinal disorders, or autonomic nervous system dysfunction.

OBJECTIVES

The aim of this Think Tank was to provide a guide on how to investigate OAB and/or detrusor underactivity (DU) patients to better clarify the underlying pathophysiology and possibly personalize the treatment.

METHODS

A compendium of discussion based on the current evidence related to phenotyping patients with OAB or DU using urodynamic tests, functional neuro-imaging, urinary markers, and microbiome.

RESULTS AND CONCLUSIONS

The article emphasizes the critical significance of adopting a comprehensive yet tailored approach to phenotyping patients with lower urinary tract (LUT) symptoms, such as OAB and UAB. The intricate interplay between the LUT and various factors, metabolic, neurological, psychological, and gastrointestinal can define unique LUT profiles, enabling personalized therapies to replace the one-size-fits-all approach.

Underactive Bladder and Detrusor Underactivity: New Advances and Prospectives

Underactive bladder (UAB) is a prevalent but under-researched lower urinary tract symptom that typically occurs alongside detrusor underactivity (DU). Unlike UAB, DU is a urodynamic diagnosis which the International Continence Society (ICS) defines as "a contraction of reduced strength and/or duration, resulting in prolonged bladder emptying and/or a failure to achieve complete bladder emptying within a normal time span". Despite the widespread prevalence of UAB/DU, there are significant gaps in our understanding of its pathophysiological mechanisms, diagnosis, and treatment compared with overactive bladder (OAB) and detrusor overactivity (DO). These gaps are such that clinicians regard UAB/DU as an incurable condition. In recent years, the understanding of UAB has increased. The definition of UAB has been clarified, and the diagnostic criteria for DU have been considered more comprehensively. Meanwhile, a number of non-invasive diagnostic methods have also been reported. Clinical trials involving novel drugs, electrical stimulation, and stem cell therapy have shown promising results. Therefore, this review summarizes recent reports on UAB and DU and highlights the latest advances in their diagnosis and treatment.

Detrusor underactivity is associated with metabolic syndrome in aged primates

Lower urinary tract (LUT) dysfunction is prevalent in the elderly population, and clinical manifestations include urinary retention, incontinence, and recurrent urinary tract infections. Age-associated LUT dysfunction is responsible for significant morbidity, compromised quality of life, and rising healthcare costs in older adults, but its pathophysiology is not well understood. We aimed to investigate the effects of aging on LUT function by urodynamic studies and metabolic markers in non-human primates. Adult (n = 27) and aged (n = 20) female rhesus macaques were evaluated by urodynamic and metabolic studies. Cystometry showed detrusor underactivity (DU) with increased bladder capacity and compliance in aged subjects. Metabolic syndrome indicators were present in the aged subjects, including increased weight, triglycerides, lactate dehydrogenase (LDH), alanine aminotransferase (ALT), and high sensitivity C-reactive protein (hsCRP), whereas aspartate aminotransferase (AST) was unaffected and the AST/ALT ratio reduced. Principal component analysis and paired correlations showed a strong association between DU and metabolic syndrome markers in aged primates with DU but not in aged primates without DU. The findings were unaffected by prior pregnancies, parity, and menopause. Our findings provide insights into possible mechanisms for age-associated DU and may guide new strategies to prevent and treat LUT dysfunction in older adults.

The effectiveness of parasympathomimetics for treating underactive bladder: A systematic review and meta-analysis

AIMS

Biological rationale suggests that parasympathomimetics (cholinergic receptor stimulating agents) could be beneficial for patients with underactive bladder. However, no systematic review with meta-analysis addressing potential benefits or adverse effects exists. The aim of this review was to assess the effectiveness, both benefits and harms, of using parasympathomimetics for the treatment of underactive bladder.

METHODS

The protocol was registered in PROSPERO, and searches undertaken in PubMed, Embase, and CENTRAL, including randomized and non-randomized controlled trials of patients with underactive bladder, comparing parasympathomimetic to placebo, no treatment, or other pharmaceuticals. Risk ratios, odds ratios, and mean differences were calculated.

RESULTS

Twelve trials with 3024 participants were included. There was a significant difference between parasympathomimetics and comparators (favoring parasympathomimetics) in the number of patients with urinary retention (risk ratio 0.55, 95% confidence interval [CI] 0.3-0.98, p = 0.04, low quality of evidence). There was no difference in mean postvoid volume overall (MD -41.4 ml, 95% CI -92.0 to 9.1, p = 0.11, low quality of evidence). There was a significant difference at up to 1 week post-intervention, favoring parasympathomimetics (MD -77.5 ml, 95% CI -90.9 to -64.1, p < 0.001, low quality of evidence), but no difference at 1 month post-intervention. There was no difference in adverse events (odds ratio 1.19, 95% CI 0.62-2.28, p = 0.6, moderate quality of evidence).

CONCLUSIONS

The evidence supporting the use of parasympathomimetics is of low quality, with relatively short follow-up durations. Overall, it is not possible to draw clear evidence-based conclusions from the current literature, presenting the use of parasympathomimetics for treating underactive bladder as a key area that requires future well-controlled clinical trials.

Irreversible Bladder Remodeling Induced by Fibrosis

Underactive bladder and impaired bladder compliance are irreversible problems associated with bladder fibrosis. Remodeling of the extracellular matrix is regarded as an important mechanism associated with bladder fibrosis. However, various risk factors and conditions contribute to the functional impairment of the bladder associated with fibrosis, and there is limited knowledge about bladder fibrosis-associated problems in the field of neurourology. Further studies are thus necessary to elucidate the underlying mechanism of bladder fibrosis and to identify effective treatment.

ACR Appropriateness Criteria® Renal Failure

Renal failure can be divided into acute kidney injury and chronic kidney disease. Both are common and result in increased patient morbidity and mortality. The etiology is multifactorial and differentiation of acute kidney injury from chronic kidney disease includes clinical evaluation, laboratory tests, and imaging. The main role of imaging is to detect treatable causes of renal failure such as ureteral obstruction or renovascular disease and to evaluate renal size and morphology. Ultrasound is the modality of choice for initial imaging, with duplex Doppler reserved for suspected renal artery stenosis or thrombosis. CT and MRI may be appropriate, particularly for urinary tract obstruction. However, the use of iodinated and gadolinium-based contrast should be evaluated critically depending on specific patient factors and cost-benefit ratio. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Is Nocturia Associated With Detrusor Underactivity?

OBJECTIVES

Detrusor underactivity (DU) is diagnosed using urodynamic testing. We hypothesized that nocturia is associated with detrusor underactivity.

METHODS

We performed a retrospective chart review of all women who underwent urodynamic testing at our institution between 2016 and 2018. Uroflowmetry and pressure-flow study parameters were compared between women with nocturia (≥2 voids/night) and without nocturia (0-1 void/night). Detrusor underactivity was diagnosed using 3 different criteria: (1) bladder voiding efficiency (BVE) of <90%, (2) bladder contractility index of <100, and (3) a composite of three urodynamic measures (Gammie criteria).

RESULTS

Of 358 women, 172 (48%) were in the nocturia group and 186 (52%) were in the no nocturia group. On uroflowmetry, median postvoid residual volume was similar (20 mL) in both groups. Median maximum flow rate (15 vs 17 mL/s, P < 0.05) and average flow rate (6 mL/s vs 7 mL/s, P < 0.05) were significantly lower in the nocturia group compared with the no nocturia group. During pressure-flow study, a significantly greater proportion of women with nocturia were unable to void around the catheter (30% vs 27%, P < 0.01). The overall rate of DU varied with the criteria used: BVE (54%), bladder contractility index (41%), and Gammie criteria (7%). The rate of DU using the BVE criteria was significantly higher in the nocturia group (63% vs 48%, P < 0.01), but no significant differences were noted using the other criteria.

CONCLUSIONS

Nocturia is associated with reduced voiding efficiency in women. The diagnosis of DU using urodynamics is challenging.

Understanding underactive bladder: a review of the contemporary literature

Underactive bladder (UAB) is characterized by prolonged voiding, hesitancy, and slow and/or intermittent stream with or without a sensation of incomplete bladder emptying. The overlap of UAB lower urinary tract symptoms with those of overactive bladder or bladder outlet obstruction, as well as its multifactorial etiology, make UAB study, as well as its diagnosis and management, a very arduous and challenging task. Therefore, despite its incidence and significant impact in the quality of life of both men and women, UAB remains a poorly understood urologic condition with insufficient and ineffective treatment options available. In this review, we will focus on the etiology theories that have been proposed and the animal models available to test those theories.

Management of Urinary Incontinence With Underactive Bladder: A Review

Urinary incontinence is caused by storage function failure, while underactive bladder (UAB) is caused by a decline in detrusor contractility and voiding dysfunction. As the treatment mechanisms for incontinence and UAB are contrary to each other, it is difficult to treat both incontinence and UAB, and the patient’s quality of life can be further degraded. Conventional midurethral sling (MUS), such as transobturator tape or retropubic MUS, introduces a risk of postoperative voiding dysfunction in stress urinary incontinence with UAB. However, there have been several reports about the efficacy and safety of conventional MUS. Adjustable sling procedures, such as transobturator adjustable tape or the Remeex system, have better outcomes than conventional MUS because they control tension both during and after surgery. When voiding dysfunction occurs after incontinence treatment with UAB, voiding symptoms can be improved by various therapeutic modalities. Clean intermittent catheterization is recommended for patients with significant increased postvoid residual volumes or urinary retention. Although pharmacotherapy such as with alpha-blockers or parasympathomimetics can be considered for UAB, there is insufficient evidence of their effect on incontinence with UAB. Future therapies, such as stem cell therapy or gene therapy, may be used to treat incontinence with UAB. The possibility of management urgency urinary incontinence that related to detrusor hyperactivity with impaired contractility using sacral neuromodulation has been suggested. Further research is needed to establish evidence for the efficacy and safety of treatments for incontinence with UAB and improve patient quality of life.

Underactive Bladder; Review of Progress and Impact From the International CURE-UAB Initiative

There is a significant need for research and understanding of underactive bladder (UAB). The International Congress of Urologic Research and Education on Aging UnderActive Bladder (CURE-UAB) was organized by Doctors Michael Chancellor and Ananias Diokno in order to address these concerns. CURE-UAB was supported, in part, by the US National Institute of Aging and National Institute of Diabetes Digestive and Kidney. Since 2014, there have been 5 successful CURE-UAB congresses. They have brought together diverse stakeholders in the UAB field to identify areas of major scientific challenge and initiated a call to action among the medical community. In this review, we will highlight current and novel treatments under development for UAB and the progress and impact from the CURE-UAB initiative.

Diagnosis and treatment of urinary and sexual dysfunction in hereditary TTR amyloidosis

Purpose

We aimed to review the current knowledge on the epidemiology, diagnosis, and management of urinary and sexual dysfunction in patients with TTR amyloidosis (ATTR).

Methods

We performed a review of the literature, screening for randomized controlled trials, prospective and retrospective series, position papers, and guidelines on urinary and sexual dysfunction in ATTR patients published in PubMed and Embase.

Results

Lower urinary tract dysfunction is present in up to 83% of patients with ATTR. Voiding symptoms are the most common, reported in 34.8−87.5% of patients, while urinary tract infections are reported in up to 50%. Urinary incontinence is observed in 16.7−37.5% of the ATTR population, mostly due to decreased urethral resistance. Sexual dysfunction affects over 40% of ATTR patients, with erectile dysfunction and sexual arousal disorder being the most common symptoms in male and female patients, respectively. In addition to a thorough clinical examination, invasive pressure-flow urodynamic testing is a cornerstone in the assessment of ATTR lower urinary tract dysfunction. The most common finding is detrusor underactivity and intrinsic sphincter deficiency. Poor bladder compliance can also be observed in patients, due to amyloid deposits on the bladder wall. Urinary tract imaging may be of interest to rule out upper urinary tract deterioration. Given the paucity of data in the ATTR population, treatment should be tailored to the individual patient.

Conclusion

Urinary and sexual dysfunction are highly prevalent in ATTR patients. Comprehensive assessment and multidisciplinary management are keys to avoiding upper urinary tract damage and improving patients’ quality of life.

Novel symptom questionnaire for the differential diagnosis of detrusor underactivity and bladder outlet obstruction in men

OBJECTIVE

To develop a questionnaire for the differential diagnosis of detrusor underactivity (DUA) and bladder outlet obstruction (BOO) without performing invasive pressure flow studies.

STUDY DESIGN AND METHODS

Symptoms of men with DUA were analyzed and compared with those of men with BOO using eight questions from the developing questionnaire. Patients with DUA have a bladder contractility index (PdetQmax+5xQmax) less than 100, whereas those with BOO have a BOO index (PdetQmax-2xQmax) greater than 40 in urodynamic studies (UDS). Men with detrusor overactivity in UDS and neurogenic issues were excluded from the analysis. One urologist reviewed patients' medical records, and responded to eight questions without using information from UDS. Scores in the developing questionnaire were then compared to make a differential diagnosis between DUA and BOO.

RESULTS

Overall, 318 men who underwent UDS were included. Symptoms were compared in patients diagnosed with DUA without BOO (n = 165) and BOO without DUA (n = 153). Questions 1, 2, 4, 5, 6, and 7 were significantly different between groups. The sensitivity and specificity of the questionnaire were 95.8% and 95.4%, respectively, for predicting DUA in patients with scores greater than 45 points (cutoff value).

CONCLUSIONS

Men with DUA and BOO may be distinguished using a developing questionnaire without invasive evaluation. Men with scores greater than 45 points would be expected to have DUA but not BOO.

Investigation of the relationship between bladder function and sarcopenia using pressure flow studies in elderly male patients

AIMS

Although detrusor underactivity is often encountered in elderly patients, the etiology remains unclear. We have hypothesized that sarcopenia was associated with impaired bladder contractility. Therefore, we have evaluated the relationship between bladder contractility and clinical parameters including sarcopenia markers in elderly male patients.

METHODS

This retrospective, single-centre study included male patients over 65 years of age who underwent a pressure flow study (PFS). We excluded patients with any previous medical histories that could affect bladder function, currently on urinary medication, and with no available data of abdominal CT scan. The psoas muscle area (PMA) (cm² /m² ) was measured as a surrogate for psoas muscle mass on computed tomography. PMA, serum CRP, and albumin are known as sarcopenia markers. Correlation and multiple regression analyses were performed to evaluate the association of bladder contractility index (BCI) with the following parameters: age, body mass index (BMI), prostate volume, bladder outlet obstruction index (BOOI), serum C-reactive protein (CRP), serum albumin, and PMA.

RESULTS

Out of 558 male patients identified in our PFS database, 119 patients were enrolled. In the correlation analysis, age, prostate volume, serum albumin, BOOI, and PMA significantly correlated with BCI. However, no significant correlation of BCI with CRP or BMI was observed. Multiple linear regression analysis showed that serum albumin, BOOI, and PMA were significantly associated with BCI.

CONCLUSIONS

We have demonstrated that serum albumin and PMA were significantly positively associated with detrusor contractility. It is possible that sarcopenia is associated with impaired detrusor contractility.

The development of the ICIQ-UAB: A patient reported outcome measure for underactive bladder

AIMS

To present the development of the International Consultation on Incontinence Questionnaire-underactive bladder (ICIQ-UAB) as the first patient reported outcome measure for the assessment of the symptoms and impact on the health-related quality of life of UAB developed in-line with the Food and Drug Administration Guidance for Industry.

METHODS

Draft items were developed following 44 semi-structured concept elicitation interviews in the UK and refined using 36 cognitive interviews. A pilot study was designed to assess the draft ICIQ-UAB's initial psychometric properties with 54 patients recruited from European hospitals. Further concept elicitation interviews were also carried out with 11 patients in the US and 10 patients in Japan. All participants had a prior urodynamic diagnosis of detrusor underactivity.

RESULTS

The cognitive interviews confirmed the initial items to be understood and interpreted as intended. Pilot testing showed that both internal consistency (Cronbach's α ≥ 0.85) and test-retest reliability (stable patients; intraclass correlation coefficient ≥ 0.88) were high. The interviews in the US and Japan elicited symptoms and impacts that support previous findings in the UK and provided further insight into the experiences of patients in those countries. The developmental ICIQ-UAB was refined using the evidence from all substudies.

CONCLUSIONS

The validity and reliability of the ICIQ-UAB were supported in a pilot study setting and the wider cultural applicability by the additional interviews in the US and Japan. Following further validation in future clinical trials, the developmental ICIQ-UAB is envisaged as an important tool for the monitoring of future UAB treatment strategies.

Female underactive bladder - Current status and management

Underactive bladder (UAB) is defined by the International Continence Society as a symptom complex characterized by a slow urinary stream, hesitancy, and straining to void, with or without a feeling of incomplete bladder emptying sometimes with storage symptoms. Until recently, the topic has received little attention in the literature probably due to a lack of consistent definitions and diagnostic criteria. We performed a literature review to identify articles related to the diagnosis and management of UAB, specifically in female patients. UAB is a common clinical entity, occurring in up to 45% of females depending on definitions used. Prevalence increases significantly in elderly women and women who live in long-term care facilities. The exact etiology and pathophysiology for developing UAB is unknown, though it is likely a multifactorial process with contributory neurogenic, cardiovascular, and idiopathic causes. There are currently no validated questionnaires for diagnosing or monitoring treatment for patients with UAB. Management options for females with UAB remain limited, with clean intermittent catheterization, the most commonly used. No pharmacotherapies have consistently been proven to be beneficial. Neuromodulation has had the most promising results in terms of symptom improvement, with newer technologies such as stem-cell therapy and gene therapy requiring more evidence before widespread use. Although UAB has received increased recognition and has been a focus of research in recent years, there remains a lack of diagnostic and therapeutic tools. Future research goals should include the development of targeted therapeutic interventions based on pathophysiologic mechanisms and validated diagnostic questionnaires.

Frequency Dependent Tibial Neuromodulation of Bladder Underactivity and Overactivity in Cats

OBJECTIVE

This study is aimed at determining if tibial nerve stimulation (TNS) can modulate both bladder underactivity and overactivity.

METHODS

In α-chloralose anesthetized cats, tripolar cuff electrodes were implanted on both tibial nerves and TNS threshold (T) for inducing toe twitching was determined for each nerve. Normal bladder activity was elicited by slow intravesical infusion of saline; while bladder overactivity was induced by infusion of 0.25% acetic acid to irritate the bladder. Bladder underactivity was induced during saline infusion by repeated application (2-6 times) of 30-min TNS (5 Hz, 4-8T, 0.2 msec) to the left tibial nerve, while TNS (1 Hz, 4T, 0.2 msec) was applied to the right tibial nerve to reverse the bladder underactivity.

RESULTS

Prolonged 5-Hz TNS induced bladder underactivity by significantly increasing bladder capacity to 173.8% ± 10.4% of control and reducing the contraction amplitude to 40.1% ± 15.3% of control, while 1 Hz TNS normalized the contraction amplitude and significantly reduced the bladder capacity to 130%-140% of control. TNS at 1 Hz in normal bladders did not change contraction amplitude and only slightly changed the capacity, but in both normal and underactive bladders significantly increased contraction duration. The effects of 1 Hz TNS did not persist following stimulation. Under isovolumetric conditions when the bladder was underactive, TNS (0.5-3 Hz; 1-4T) induced large amplitude and sustained bladder contractions. In overactive bladders, TNS during cystometry inhibited bladder overactivity at 5 Hz but not at 1 Hz.

CONCLUSIONS

This study indicates that TNS at different frequencies might be used to treat bladder underactivity and overactivity.

Recent advances in the understanding and management of underactive bladder

Underactive bladder (UAB) is an important and complex urological condition resulting from the urodynamic finding of detrusor underactivity. It can manifest in a wide range of lower urinary tract symptoms, from voiding to storage complaints, and can overlap with other conditions, including overactive bladder and bladder outlet obstruction. However, UAB continues to be poorly understood and inadequately researched. In this article, we review the contemporary literature pertaining to recent advances in defining, understanding, and managing UAB.

Characterization of voiding function and structural bladder changes in a rat model of neurogenic underactive bladder disease

OBJECTIVES

To create an animal model for neurogenic underactive bladder disease (UAB) and identify markers to describe secondary myogenic changes in the bladder wall.

MATERIALS AND METHODS

Male rats underwent either bilateral pelvic nerve injury or sham surgery. Four weeks after surgery functional evaluation was performed and tissue was harvested. Functional evaluation consisted of analysis of voiding pattern, 24-h urine collection in a metabolic cage, in vivo cystometry and in-vitro contractile function assessment. PCR and immunohistochemical localization of different smooth muscle cell and extracellular matrix markers was performed on bladder strips.

RESULTS

After pelvic nerve injury, dry bladder weight increased and voiding contractions were absent, resulting in overflow incontinence. In-vitro contractile response to carbachol was decreased. This was paired with an upregulation of synthetic smooth muscle cell (SMC) markers mRNA expression such as retinol binding protein 1 (RBP1), myosin 10 (MYH10) and osteopontin (OPN), and a downregulation of contractile SMC marker smoothelin (SMTL). The SMTL/OPN mRNA ratio was 50 times higher in sham bladders compared to PNI bladders.

CONCLUSIONS

The loss of in-vivo and in-vitro contractile function following pelvic nerve transection is characterized by a switch from a contractile to synthetic SMC phenotype, which is best characterized by the ratio SMTL/OPN mRNA expression. Modulating this phenotypical switch is a potential target for the development of UAB therapy. We suggest for the first time a set of markers that may be useful to evaluate therapeutic strategies on improvements in bladder wall structure.

Clinical implications of underactive bladder

Underactive bladder (UAB) is a common urologic condition but a complex disease that causes troublesome lower urinary tract symptoms. Currently, management of UAB remains unsatisfactory. Also, many urological diseases can be combined with UAB. In these combined cases, the treatment results may be affected by UAB component. This review focuses on the clinical implications of UAB in patients with common urologic conditions, including bladder outlet obstruction, overactive bladder syndrome and stress urinary incontinence.

Definition and symptoms of underactive bladder

Underactive bladder (UAB) is a symptom syndrome reflecting the urodynamic observation of detrusor underactivity (DU), a voiding contraction of reduced strength and/or duration, leading to prolonged or incomplete bladder emptying. An International Continence Society Working Group has described UAB as characterised by a slow urinary stream, hesitancy and straining to void, with or without a feeling of incomplete bladder emptying and dribbling, often with storage symptoms. Since DU often coexists with bladder outlet obstruction, or storage dysfunction (detrusor overactivity or incontinence), the exact contribution of the DU to the presenting complaints can be difficult to establish. The presence of voiding and post voiding lower urinary tract symptoms (LUTS) is implicitly expected in UAB, but a reduced sensation of fullness is reported by some patients, and storage LUTS are also an important factor in many affected patients. These may result from a postvoid residual, but often they do not. The storage LUTS are often the key driver in leading the patient to seek healthcare input. Nocturia is particularly common and bothersome, but what the role of DU is in all the range of influences on nocturia has not been established. Qualitative research has established a broad impact on everyday life as a result of these symptoms. In general, people appear to manage the voiding LUTS relatively well, but the storage LUTS may be problematic.

A 3D Printed Implantable Device for Voiding the Bladder Using Shape Memory Alloy (SMA) Actuators

Underactive bladder or detrusor underactivity (DU) is defined as a reduction of contraction strength or duration of the bladder wall. Despite the serious healthcare implications of DU, there are limited solutions for affected individuals. A flexible 3D printed implantable device driven by shape memory alloys (SMA) actuators is presented here for the first time to physically contract the bladder to restore voluntary control of the bladder for individuals suffering from DU. This approach is used initially in benchtop experiments with a rubber balloon acting as a model for the rat bladder to verify its potential for voiding, and that the operating temperatures are safe for the eventual implantation of the device in a rat. The device is then implanted and tested on an anesthetized rat, and a voiding volume of more than 8% is successfully achieved for the SMA-based device without any surgical intervention or drug injection to relax the external sphincter.