Detrusor nerve radiofrequency ablation (DENERA): Experimental study of safety and efficacy in an ovine model.

PURPOSE: The subtrigonal perivesical nerve plexus contains a large proportion of the bladder's innervation. A transurethral radiofrequency ablation approach has successfully denervated this region to alleviate overactive bladder symptoms, with some urothelial heat injury. We report a novel transvaginal RFA device (DENERA) and assess its feasibility and efficacy in denervating the perivesical nerve plexus of in vivo sheep. METHODS: In 14 adult female in vivo sheep, pulsed radiofrequency energy was applied transvaginally for three cycles of 4 min, maintaining the tissue temperature at 45°C, with 30 s of rest between each cycle. The control group (n = 4) was sacrificed without ablation, and various groups were sacrificed 1 week (n = 3), 4 weeks (n = 4), and 12 weeks (n = 3) after ablation. The bladder subtrigones were harvested then analyzed with H&E, S100, and TH immunostaining to quantify their neural density and neural vacuolization. RESULTS: The ablation procedure increased the neural vacuolization the most at 1 week and decreased the neural density the most at 4 weeks, with both variables displaying a significant change followed by a slight rebound towards baseline at 12 weeks. The H&E analysis showed that the needles penetrated deep into the subtrigonal detrusor muscle. The sheep recovered from the procedure with no complications or damage in the bladder wall or urothelium. CONCLUSIONS: This study shows that one DENERA treatment can cause subtrigonal denervation with some rebound afterwards and no complications. DENERA may become a promising OAB treatment option that can ablate the perivesical plexus without harming the urothelium.

Foreign body granuloma development after calcium hydroxylapatite injection for stress urinary incontinence: A literature review and case report.

Objectives: To present a case of foreign body granuloma (FBG) development after injection of calcium hydroxylapatite as a urethral bulking agent and to review all documented cases of this phenomenon in the literature. Methods: We analyzed a new case of calcium hydroxylapatite-induced FBG. We also conducted a literature review of the PubMed, Embase, CINAHL, and Web of Science databases through March 2022. Reports were included if they contained stress urinary incontinence patients that developed an FBG after calcium hydroxylapatite injection. The cases were reviewed for presenting symptoms, patient demographics, granuloma details, and surgical treatment. Results: We screened 250 articles and included six articles between 2006 and 2015 in addition to the present case. The median age of the patients was 65.5 years (range 45-93), and all patients were female. The most common presenting symptoms and the proportion of patients affected were difficulty voiding (4/8), recurrent urinary incontinence (3/8), and dyspareunia (2/8). The median time between the first CaHA injection and discovery of the FBG was 5 months (range 1-50). The median longest dimension of the FBGs was 1.85 cm (range 1.0-3.0). The 8 masses observed were evenly distributed throughout the urethra, with 3 in the bladder neck, 2 in the midurethra, and 3 in the distal urethra. Surgical excision was the predominant management choice, with some variation in technique. Conclusions: Severe, persistent lower urinary tract symptoms after calcium hydroxylapatite injection may indicate an FBG, which has been successfully managed with surgical excision.

Safety and efficacy of polydimethylsiloxane (Macroplastique®) in women with stress urinary incontinence: analysis of data from patients who completed three years follow-up.

INTRODUCTION AND HYPOTHESIS: This study aimed to report 3-year completed follow-up of the safety and efficacy of Macroplastique® (MPQ) in women with stress urinary incontinence (SUI) due to intrinsic sphincter deficiency (ISD). METHODS: This is a retrospective analysis of all women who completed 3-year follow-up post-MPQ injection(s) at ten medical centers. We used the ROSE registry data report of Macroplastique® [Macroplastique® Real-time Observation of Safety and Effectiveness (ROSE) registry P040050/PAS001 on 2017]. Subjective incontinence outcome and adverse effects were assessed. RESULTS: The study included all patients (n = 70) who completed 3-year follow-up after the last MPQ injection. Twenty-four of 70 (34%) patients had two injections; 21/70 (30%) patients reported Stamey grade 0 and 28/70 (40%) reported Stamey grade 1. The overall patient satisfaction was 68% who completed 3-year follow-up. The composite success rate (I-QoL, PGI-S, and Stamey grade improvement) was 51.4%. No serious adverse events (AE) were reported within the completed 3-year follow-up. CONCLUSIONS: MPQ was found to be safe and efficacious for the treatment of SUI secondary to ISD in women. The overall high satisfaction rate was sustained from baseline to 3 years post-injection. Most complications were minor and transient without sequelae.

An International Continence Society (ICS) report on the terminology for female pelvic floor fistulas.

INTRODUCTION: The terminology for female pelvic floor fistulas (PFF) needs to be defined and organized in a clinically based consensus Report. METHODS: This Report combines the input of members of the International Continence Society (ICS) assisted at intervals by external referees. Appropriate core clinical categories and a sub-classification were developed to give a coding to definitions. An extensive process of 19 rounds of internal and external review was involved to examine each definition, with decision-making by collective opinion (consensus). RESULTS: A terminology report for female PFF, encompassing 416 (188 NEW) separate definitions, has been developed. It is clinically based with the most common diagnoses defined. Clarity and user-friendliness have been key aims to make it interpretable by practitioners and trainees in different specialty groups involved in female pelvic floor dysfunction and PFF. Female-specific imaging (ultrasound, radiology, and magnetic resonance imaging) and conservative and surgical PFF managements as well as appropriate figures have been included to supplement and clarify the text. Interval (5-10 years) review is anticipated to keep the document updated and as widely acceptable as possible. CONCLUSION: A consensus-based terminology report for female PFF has been produced to aid clinical practice and research.

Potential Role of Monocyte Chemoattractant Protein-1 in Monitoring Disease Progression and Response to Treatment in Overactive Bladder Patients.

PURPOSE: To compare urinary levels of monocyte chemoattractant protein-1 (MCP-1), an inflammatory cytokine, in healthy controls and overactive bladder (OAB) patients, to correlate changes in urinary MCP-1 with OAB treatment response and symptom severity, and to study the diagnostic potential of MCP-1 for OAB, as well as the efficacy of MCP-1 as a potential biomarker for different phenotypes of OAB. METHODS: We used enzyme-linked immunosorbent assay to measure normalized urinary MCP-1 levels in 56 individuals (43 OAB patients and 13 controls). We assessed the OAB patients at 3 visits with 2 validated symptom severity questionnaires (OAB-V8 and Patient Perception of Bladder Condition). RESULTS: The mean pretreatment urinary MCP-1 level at visit 1 (229.2-pg/mg creatinine) was significantly greater than the MCP-1 levels at visit 3 in both the treatment (107.0-pg/mg creatinine) (P<0.001) and control (52.35-pg/mg creatinine) groups (P<0.001). Average OAB symptom severity decreased significantly from visit 1 (baseline) to visits 2 (4 weeks) and 3 (12-14 weeks) and was significantly correlated with urinary MCP-1 levels. Urinary MCP-1 levels dropped significantly (P=0.002) posttreatment in patients whose symptom severity improved by >30%, whereas nonresponders displayed no significant MCP-1 decrease (P=0.164). The receiver operating characteristic analysis of the OAB visit 1 and control groups produced an area under the curve of 0.891. We found no significant differences in sex, race, or age between the OAB and control groups. CONCLUSION: MCP-1 levels differed significantly between the control and OAB groups and were closely correlated with symptom severity and treatment response. The good diagnostic accuracy of MCP-1 for OAB suggests the potential usage of MCP-1 for OAB diagnosis. The varying response of urinary MCP-1 levels to treatment may indicate at least 2 potential phenotypes of OAB. MCP-1, in combination with other biomarkers and symptom severity questionnaires, could potentially aid in developing a patient-centered OAB treatment approach.

Workup and conservative management of ileal conduit-vaginal fistulas: review of literature.

Ileal conduit-vaginal fistulas are a rare but challenging complication of urinary diversion. Here we identify risk factors and summarize the workup and conservative management strategies for this complication. We present two cases of elderly women with remote history of cancer who presented with persistent urinary leakage from the vagina several years after ileal conduit creation. Fistulas may be identified using dye or imaging with a loopogram and looposcopy. Correction of obstruction such as stomal stenosis or urinary diversion should be pursued to relieve pressure off the conduit. Minimally invasive management such as fulguration can result temporary relief; however, the recurrence rate is high.

Initial Evaluation of a Novel Modulated Radiofrequency-based Bladder Denervation Device.

OBJECTIVE: To determine if targeted and modulated radiofrequency ablation (RFA) of the urinary bladder using our novel ablation device (Denerblate) reduces bladder nerve density, potentially leading to a novel strategy for the management of overactive bladder. METHODS: Fifteen pigs were divided into 4 groups: control (n = 3), 1-week (n = 4), 4-week (n = 4) and 12-week (n = 4) survival times. Denerblate was deployed on the trigone area of the bladder. Three 240-second cycles of modulated RFA were applied with 30 seconds between cycles. At the end of each survival term, urinary bladders were harvested for histopathologic evaluation. Nerve count and density were manually calculated. RESULTS: All procedures were successfully completed, and all animals survived to the desired time points. Mean nerve density (nerves/mm2) was highest in the control and 1-week survival group compared to the 4-week and 12-week groups, both of which demonstrated significant diminishment. Nerve density in the bladder neck at control, 1 week, 4 weeks, and 12 weeks were 1.8, 1.35, 0.87, and 0.12, respectively (P <.001). Nerve density in the bladder trigone area at control, 1 week, 4 weeks, and 12 weeks were 1.5, 0.98, 0.65, and 0.112, respectively (P <.001). Epithelial heat injury was observed in 14.3% at 1 week, 10.7% at 4 weeks, but completely resolved by 12 weeks. CONCLUSION: In the porcine model, modulated RFA delivered by our novel device reduced nerve density in the bladder neck and trigone by 88.6% and 88.9% at 12 weeks without evidence of lasting epithelial injury.

Clinical experience with percutaneous tibial nerve stimulation in the elderly; do outcomes differ by gender?

Objective: To evaluate the use of percutaneous tibial nerve stimulation (PTNS) in an elderly population, as PTNS is a third-line treatment in the management of overactive bladder (OAB) and affects 10-26% of adult males and 8-42% of adult females, increasing in prevalence with age. Patients and methods: We performed a chart review of patients aged ≥ 65 years undergoing PTNS at a single institution over 6 years. We examined clinicopathological variables potentially associated with the outcomes of interest. Results: In total, 52 patients aged ≥ 65 years underwent an induction course of PTNS between 2011 and 2017, comprising 23 men and 29 women. The mean age of the patients was 75.75 years and the mean body mass index (BMI) was 26.33 kg/m2. In all, 36 patients used anticholinergic treatments prior to PTNS, five used a ß3-adrenoceptor agonist, and three had Botox injections. After PTNS, 37 patients reported improvement of their symptoms, with 21 using combined therapy during PTNS. Only seven patients used an anticholinergic after PTNS, six used a ß3-adrenoceptor agonist, five had Botox injections, and two had sacral neuromodulation. When looking at variables such as age, gender, race, BMI, and comorbidities, we found that an obese BMI was the only statistically significant variable predicting failure of response. A sub-analysis of only women did not demonstrate any predictors of failure. Conclusion: Our subjective response rate of 70% was within the success rates reported in literature. In all, 39% of patients used a concomitant treatment during PTNS and 13.2% required alternative treatment after PTNS. Abbreviations: BMI: body mass index; OAB: overactive bladder; PTNS: percutaneous tibial nerve stimulation; UI: urinary incontinence.

Characterisation of urinary monocyte chemoattractant protein 1: Potential biomarker for patients with overactive bladder.

Objective: To investigate urinary monocyte chemoattractant protein 1 (MCP-1) as a potential marker for idiopathic overactive bladder (OAB). This is a quantitative measurement of urinary MCP-1 to establish baseline normal values that could help in future index studies. Normalised urinary MCP-1 levels are measured in female patients with OAB and aged-matched controls. Severity of OAB symptoms is correlated to normalised urinary MCP-1 levels. Patients and methods: Urinary MCP-1 levels were measured in 29 female patients with OAB and 10 normal female controls. The patients with OAB were either newly diagnosed or off any OAB oral therapy for at least 2 weeks. OAB symptoms were assessed using validated OAB questionnaires. Urinary MCP-1 levels were measured using enzyme-linked immunosorbent assay and normalised by urinary creatinine (Cr) levels. Results: The baseline urinary MCP-1 levels in female patients with OAB were significantly higher than those of the controls, at a mean of 210.25 vs 48.02 pg/mg Cr (P < 0.001). Patients who had severe OAB bother symptoms had higher levels of urinary MCP-1 (r = 0.03), also patients with OAB-wet had higher levels of urinary MCP-1, at a mean (SEM) of 209.25 (30.5) vs OAB-dry 185.25 (10) pg/mg Cr (P < 0.001). Conclusion: Urinary MCP-1 levels were higher in female patients with idiopathic OAB. The close association of urinary MCP-1 and OAB bother severity symptoms and OAB-wet suggest that inflammation plays a major role in the pathophysiological mechanisms underlying the sensitisation of bladder afferent nerves. Establishing urinary MCP-1 levels in patients with OAB hopefully will help future studies to confirm the correlation as a baseline and changes with treatments. Abbreviations: BMI: body mass index; Cr: creatinine; MCP-1: monocyte chemoattractant protein 1; OAB: overactive bladder; OAB-q: Overactive Bladder Questionnaire; PPBC: Patient Perception of Bladder Condition; UI: urinary incontinence.

Spinal cord stimulation ameliorates detrusor over-activity and visceromotor pain responses in rats with cystitis.

AIM: Interstitial cystitis/painful bladder syndrome/(IC/PBS) results in recurring pain in the bladder and surrounding pelvic region caused by abnormal excitability of micturition reflexes. Spinal cord stimulation (SCS) is currently clinically used for the attenuation of neuropathic and visceral pain. The present study examined whether SCS at upper lumbar segments modulates detrusor overactivity and visceral hyperalgesia associated with cystitis in a rat model of cyclophosphamide (CYP)-induced cystitis. METHODS: Cystitis was induced by intraperitoneal injection of CYP (200 mg/kg) in six adult female Sprague Dawley rats 48 h prior to urodynamic recordings. Another six rats served as-controls with saline injection. Cystometry and the external urethral sphincter (EUS) electromyography during bladder infusion were evaluated under urethane anesthesia. The visceromotor reflexes (VMR) obtained from the external abdominal oblique muscle were quantified during bladder infusion and isotonic bladder distension (IBD), respectively. After baseline recordings were taken, SCS was applied on the dorsal surface of L3 for 25 min. Urodynamic recordings and VMR during bladder infusion and IBD were repeated 2 h after SCS. RESULTS: CYP resulted in detrusor overactivity, stronger EUS tonic contractions, and increased VMR. SCS significantly reduced non-voiding contractions, prolonged EUS relaxation, and delayed VMR appearance during bladder infusion as well as significantly decreased VMR during IBD in cystitis rats. CONCLUSION: SCS improved bladder function and EUS relaxation during bladder infusion and significantly attenuated visceral nociceptive-related VMR during IBD in cystitis rats. SCS may have therapeutic potential for patients with hyperalgesia and IC/PBS.

Investigations of urethral sphincter activity in mice with bladder hyperalgesia before and after drug administration of gabapentin.

PURPOSE: This study investigated the effect of gabapentin on lower urinary tract dysfunction focusing on urethral activities and cystitis-induced hyperalgesia in a mouse model of painful bladder syndrome/interstitial cystitis (PBS/IC). The electromyography (EMG) of external urethral sphincter (EUS) was difficult to obtain, but contained useful information to examine the drug effect in mice. METHODS: Female C57BL/6J mice were intraperitoneally (ip) administration with either saline or 200 mg/kg of cyclophosphamide (CYP) 48 h before experimental evaluation. Cystitis mice were treated with administration of gabapentin (25 or 50 mg/kg, ip). Cystometry and EUS EMG were obtained and analyzed during continuous bladder infusion. The visceral pain-related visceromotor reflex (VMR) was recorded in response to isotonic bladder distension. RESULTS: Cystitis mice showed shorter inter-contraction intervals and increased occurrence of non-voiding contractions during bladder infusion, with increased VMR during isotonic bladder distension, indicating cystitis-induced bladder hyperalgesia. Gabapentin (50 mg/kg) suppressed effects of CYP on cystometry, but not on EUS EMG activity, during bladder infusion. The effect on urodynamic recordings lasted 4 h. VMR was significantly reduced by gabapentin. CONCLUSIONS: The present study showed that CYP-induced cystitis in mice is a model of visceral hyperalgesia affecting detrusor contractions, not urethral activations. The technique of using EUS EMG to evaluate the drug effects on urethral activities is novel and useful for future investigations. Gabapentin can be as a potential treatment for detrusor overactivity and PBS/IC.

Autologous rectus fascia sling for treatment of stress urinary incontinence in women: A review of the literature.

AIMS: Stress urinary incontinence (SUI) is common in the adult females. Surgical treatment options include synthetic mid-urethral sling (MUS), autologous sling, bulking agents, and Burch colposuspension. The autologous pubovaginal sling (PVS) has re-emerged in response to complications of synthetic MUSs and FDA communications regarding the use of vaginal mesh. This resulted in patients' fear related to vaginal mesh and drop in number of patients seeking surgical treatment of SUI. PVS has re-emerged as an option for treatment of primary SUI. The aim of this review is to familiarize, disseminate information, and share tips for the practicing female pelvic surgeons related to the practice of the autologous fascia sling. METHODS: We reviewed the literature related to the autologous sling. We used the following data bases and search engines: GoPubMed (Transinsight), Cochrane reviews (Wiley Interscience), google scholar (google), and Scopus (Elsevier). Because it is the most commonly investigated and utilized, we focused on the autologous rectus fascia sling. We also focused on the retropubic sling approach because the literature on transobturator rectus fascia sling is sparse. RESULTS: Out of 307 articles related to the subject found, 22 articles were included and the rest were excluded. CONCLUSION: ARFS is a valid primary method of treatment for female SUI. Also, it is used in particular indications such as patients with intrinsic sphincter deficiency (ISD), prior pelvic irradiation, failed and/or complicated synthetic MUS, and violated urethral lumen.

Face, Content, and Construct Validations of Endoscopic Needle Injection Simulator for Transurethral Bulking Agent in Treatment of Stress Urinary Incontinence.

INTRODUCTION AND OBJECTIVES: Endoscopic injection of urethral bulking agents is an office procedure that is used to treat stress urinary incontinence secondary to internal sphincteric deficiency. Validation studies important part of simulator evaluation and is considered important step to establish the effectiveness of simulation-based training. The endoscopic needle injection (ENI) simulator has not been formally validated, although it has been used widely at University of California, Irvine. We aimed to assess the face, content, and construct validity of the UC, Irvine ENI simulator. METHODS: Dissected female porcine bladders were mounted in a modified Hysteroscopy Diagnostic Trainer. Using routine endoscopic equipment for this procedure with video monitoring, 6 urologists (experts group) and 6 urology trainee (novice group) completed urethral bulking agents injections on a total of 12 bladders using ENI simulator. Face and content validities were assessed by using structured quantitative survey which rating the realism. Construct validity was assessed by comparing the performance, time of the procedure, and the occlusive (anatomical and functional) evaluations between the experts and novices. Trainees also completed a postprocedure feedback survey. Effective injections were evaluated by measuring the retrograde urethral opening pressure, visual cystoscopic coaptation, and postprocedure gross anatomic examination. RESULTS: All 12 participants felt the simulator was a good training tool and should be used as essential part of urology training (face validity). ENI simulator showed good face and content validity with average score varies between the experts and the novices was 3.9/5 and 3.8/5, respectively. Content validity evaluation showed that most aspects of the simulator were adequately realistic (mean Likert scores 3.9-3.8/5). However, the bladder does not bleed, and sometimes thin. Experts significantly outperformed novices (p < 001) across all measure of performance therefore establishing construct validity. CONCLUSION: The ENI simulator shows face, content and construct validities, although few aspects of simulator were not very realistic (e.g., bleeding).This study provides a base for the future formal validation for this simulator and for continuing use of this simulator in endourology training.

Are Electronic and Paper Questionnaires Equivalent to Assess Patients with Overactive Bladder?

PURPOSE: Overactive bladder syndrome is defined as urinary urgency, usually accompanied by frequency and nocturia, with or without urgency urinary incontinence in the absence of urinary tract infection or another obvious pathological condition. Electronic questionnaires have been used in a few specialties with the hope of improving treatment outcomes and patient satisfaction. However, they have not been widely used in the urological field. When treating overactive bladder, the main outcome is to improve patient quality of life. The primary objective of this study was to evaluate whether electronic questionnaires would be equally accepted as or preferred to paper questionnaires. The secondary objective was to look at the preference in relation to patient age, education and iPad® tablet familiarity. MATERIALS AND METHODS: We prospectively evaluated the iList® electronic questionnaire application using a friendly iPad tablet in patients with overactive bladder who presented to the urology clinic at our institution. Each of the 80 patients who were recruited randomly completed the validated OABSS (Overactive Bladder Symptom Score) and the PPBC (Patient Perception of Bladder Condition) questionnaires in paper and electronic format on the tablet. Variables potentially associated with the outcomes of interest included demographic data, questionnaire method preference, patient response rate and iPad familiarity. We used the 2-sided Z-test to determine whether the proportion of patients who considered the tablet to be the same, better or much better than paper was significantly greater than 50%. The 2-sided chi-square test was applied to assess whether the intervention effect significantly differed among the demographic subgroups. RESULTS: A total of 80 patients 21 to 87 years old were enrolled in the study from November 2015 to August 2016. Of the patients 53% were female and 49% were 65 years or younger. The incidence of those who considered the tablet to be the same or better than paper was 82.5% (95% CI 74.2-90.8, p <0.001). The incidence of patients who considered the tablet to be the same or better than paper ranged from 76% to 97% regardless of age, gender and education subgroup as well as in those with any familiarity with the tablet (each p <0.001). Of the 20 patients who were not familiar with the tablet 45% preferred the electronic questionnaire (p = 0.654). CONCLUSIONS: We found that the proportion of patients who considered electronic questionnaires to be equivalent to or better than paper versions was higher than those who preferred paper questionnaires regardless of age, gender or education level.

Surgical technique for removal of tined lead for InterStim.

INTRODUCTION: We aimed to introduce our technique describing the removal of a chronic implanted tined-lead in patients with a sacral neuromodulator implant. MATERIALS AND METHODS: We performed a retrospective review of patients who had chronic sacral neuromodulator (InterStim) implanted by a single surgeon from 2001 through 2015. This simple surgical technique was developed and successfully performed to remove the leads. Primary reasons for removal were elective due to poor symptoms control and failure to maintain response or lead migration. Patient demographics, indication for implantation, as well as installation and removal complications were recorded and analyzed. RESULTS: Twenty-five patients were included [mean age: 60.4 years (32-86), 17 females]. Primary indications for sacral nerve stimulation were overactive bladder in 16 (64%), mixed incontinence in 6 (24%), urinary retention in 2 (8%), and interstitial cystitis 3 (12%). Mean implant duration was 24.2 (0.5-90) months. The existing tined lead was removed and replaced in 11 (44%) patients while the remaining 14 (56%) underwent complete removal of the unit without subsequent replacement. Successful lead removal without complications was achieved in 24 (96%) patients. CONCLUSIONS: This minimally invasive technique is a simple, safe, and effective method of removing chronic implanted tined leads en bloc.

Postpartum stress urinary incontinence, is it related to vaginal delivery?

A postpartum stress urinary incontinence is highly prevalent in Chinese women. Both pregnancy and delivery can damage muscular, fascial, and neural mechanisms of urinary continence. Elective cesarean section (CS) is not completely protective against postpartum stress urinary incontinence.

The challenges in the diagnosis of detrusor underactivity in clinical practice: A mini-review.

OBJECTIVE: To review the current definitions, terminology, epidemiology and aetiology of detrusor underactivity (DU), with specific attention to the diagnostic criteria in use. In addition, we address the relation and the overlap between DU and bladder outlet obstruction (BOO). In this mini-review, we hope to help identify DU patients and facilitate structured clinical evaluation and research. METHODS: We searched the English literature using ScienceDirect and PubMed for relevant articles. We used the following terms: 'detrusor underactivity', 'underactive bladder', 'post voiding residual', 'post micturition residual', 'acontractile bladder', 'detrusor failure', and 'detrusor areflexia'. RESULT: DU is one of the most common conditions causing lower urinary tract symptoms (LUTS). Unfortunately, it is also the most poorly understood bladder dysfunction with scant research. To our knowledge there is no clear definition and no non-invasive method to characterise this important clinical condition. DU may result from the normal ageing process; however, it has multiple aetiologies including neurogenic and myogenic dysfunction. In many cases the symptoms of DU are similar to those of BOO and it usually requires invasive urodynamic study (UDS) for diagnosis to differentiate the two diagnoses. A number of diagnostic tests may be used including: UDS testing, the Schafer pressure/flow nomogram, linear passive urethral resistance relation, Watts factor, and the bladder contractility index. Of these, UDS testing is the most practical as it determines both the maximum urinary flow rate and the pressure exerted by the detrusor muscle relative to the maximal flow of urine, allowing for precise characterisation of detrusor function. CONCLUSION: Currently, the diagnosis of DU is based on invasive urodynamic parameters as defined by the International Continence Society in 2002. There is no consensus for the definition of DU prior to 2002. As there is significant overlap between the symptoms of DU and BOO, it is difficult to diagnose DU clinically.