Noninvasive Techniques for the Measurement of Isovolumetric Bladder Pressure

The mechanical stop test and isovolumetric detrusor contractile reserve are associated with immediate spontaneous voiding after transurethral resection of prostate

PURPOSE

To identify urodynamic factors associated with the mechanical stop test and immediate spontaneous voiding following transurethral resection of prostate (TURP).

METHODS

We identified 90 men who underwent TURP over a 12-month period. Forty-three (mean age 68 years) underwent urodynamic evaluation prior to TURP. Isovolumetric detrusor contractile pressure (P_iso) was obtained using the mechanical stop test during the voiding phase, and used to calculate detrusor contractile reserve (P_res = P_iso - P_det@Q_max). Primary outcome was spontaneous voiding after TURP.

RESULTS

Preoperative catheter-free spontaneous voiding was present in 63% of men (27/43) with a urodynamic (mean ± SD): Q_max 6.2 ± 2.7 mL/s, P_det@Q_max 102 ± 47 cmH₂O, P_iso 124 ± 49 cmH₂O, P_res 22 ± 16 cmH₂O, bladder outlet obstruction index (BOOI) 90 ± 49, and bladder contractility index (BCI) 132 ± 44. The remaining 16 catheter-dependent men demonstrated a urodynamic (mean ± SD): Q_max 3.6 ± 3.3 mL/s, P_det@Q_max 87 ± 38 cmH₂O, P_iso 99 ± 51 cmH₂O, P_res 10 ± 18 cmH₂O, BOOI 82 ± 36, and BCI 106 ± 48. Following TURP, 67% of men voided spontaneously with their first void trial, and in receiver operator analysis of urodynamic measures (P_det@Q_max, P_iso, P_res, BOOI and BCI), only P_res was significantly associated with immediate spontaneous voiding after TURP (threshold P_res ≥ 9 cmH₂O, AUC = 0.681, p = 0.035).

CONCLUSIONS

In men who underwent TURP, a P_res ≥ 9 cmH₂O was associated with immediate spontaneous voiding and may be easily incorporated into the postoperative pathway.

Penile Compression Release Index Revisited: Evaluation and Comparison with Other Noninvasive Tools in the Prediction of Bladder Outlet Obstruction in Men with Benign Prostatic Enlargement

Aim:

To determine the discriminatory power of penile urethral compression-release index (PCRI), clinical prostate score (CLIPS) and bladder outlet obstruction index 2 (BOON2) for the detection of bladder outlet obstruction (BOO), and the associated bladder abnormality in patients with benign prostatic enlargement (BPE).

Material and methods:

In study was included of 135 patients with proven BPE underwent urodynamic measurement (UDM) and PCR maneuver. PCR Index was calculated following the formula: (Qs-Qss)/Qss x 100(%). CLIPS score was calculated based on non-invasive variables (prostate volume, maximal urinary flow, residual urine and voided volume), while BOON2 was calculated using the formula intravesical prostate protrusion (IPP)-3 x Qmax-0.2 x mean voided volume. UDM results were plotted on Schaefer and URA nomograms.

Results:

A comparative analysis was made using ROC curves. The area under the curve (AUC) for PCRI is 0.85 (PTP 91.3%), while AUC for CLIPS and BOON2 is 0.8 (PTP 77.6%) and 0.82 (PTP 74.5%), respectively. PCRI with the cut-off point of 96% clearly distinguishes obstructed patients with normocontractile detrusor and the presence of detrusor overactivity (DO), versus those unobstructed. CLIPS (>10) shows good BOO prediction, but without the possibility of distinguishing between detrusor contractility grade and the occurrence of DO. BOON2 has shown that impaired contractility has influence on this number in obstructed patients.

Conclusion:

PCRI is a very good noninvasive urodynamic test for a group-wise detection of BOO in patients with BPE and associated bladder co-morbidities; it is therefore superior in comparison with to CLIPS or BOON2.

The Use of Urodynamics Assessment Before the Surgical Treatment of BPH

Lower urinary tract symptoms (LUTS) are a common problem in men especially with aging. The International Continence Society (ICS) revealed an overall prevalence of LUTS of about two-thirds of men age 40 years and above. The treatment approach depends on accurate determination of the underlying etiology. LUTS is not unique to benign prostate enlargement (BPE) and can be secondary to other causes. In the era where quality of care is important, accurate diagnosis and counseling to meet patients' expectations is of extreme paramount. Thus, proper assessment of patients who present with BPE and LUTS should be an important part of the work up process. Accurate diagnosis and identification of the cause will help to improve quality of treatment, optimize counseling, and improve treatment outcomes. Pressure flow urodynamic studies (PFUDs) are not only important tools that help to identify the underlying causes of LUTS; it is considered the "gold standard" for diagnosis of bladder outlet obstruction (BOO) in patients with enlarged prostate [1, 2]. However, there is a continuous debate on the value of using PFUDs and its association with improved outcomes.

Simple Modification of the Bladder Outlet Obstruction Index for Better Prediction of Endoscopically-Proven Prostatic Obstruction: A Preliminary Study

Purpose

The bladder outlet obstruction index (BOOI), also known as the Abrams-Griffiths (AG) number, is the most widely used index for predicting BOO. However, the obstructed prostatic urethra determined by the BOOI is often inconsistent with endoscopically-proven obstruction. We assessed abdominal straining pattern as a novel parameter for improving the prediction of BOO.

Materials and Methods

We retrospectively reviewed the pressure-flow studies (PFS) and cystourethroscopy in 176 BPH/LUTS patients who were unresponsive to medical therapy. During PFS, some groups of patients tried to urinate with abdominal straining, which can increases intravesical pressure and underestimate BOOI theoretically. Accordingly, the modified BOOI was defined as (P_detQ_max+ΔP_abd)-2Q_max.

Results

Ultimately, 130 patients were eligible for the analysis. In PFS, ΔP_abd (P_abdQ_max-initial P_abd) was 11.81±13.04 cmH₂O, and it was 0–9 cmH₂O in 75 (57.7%), 10–19 cmH₂O in 23 (17.7%) and ≥20 cmH₂O in 32 (24.6%) patients. An endoscopically obstructed prostatic urethra in 92 patients was correctly determined in 47 patients (51.1%) by the original BOOI versus 72 patients (78.3%) based on the modified BOOI. Meanwhile, an “unobstructed” urethra according to the original BOOI was present in 11 patients (12.0%), whereas according to the modified BOOI, only 2 (2.1%) would be labeled as “unobstructed”. In receiver operating characteristic curves, the area under the curve was 0.906 using the modified BOOI number versus 0.849 in the original BOOI (p<0.05).

Conclusions

The change in abdominal pressure was correlated with endoscopically-proven obstruction. Our simple modification of the BOOI on the basis of this finding better predicted bladder outlet obstruction and, therefore, should be considered when evaluating BOO in patients with LUTS/BPH.

The role of noninvasive penile cuff test in patients with bladder outlet obstruction

PURPOSE

The aim of this study was to compare the penile cuff test (PCT) and standard pressure-flow study (PFS) in patients with bladder outlet obstruction.

MATERIALS AND METHODS

A total of 58 male patients with moderate to severe lower urinary tract symptoms (LUTS) were selected. Seven patients were excluded; thus, 51 patients were finally enrolled. Each of the patients underwent a PCT and a subsequent PFS. The sensitivity (SE), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), and likelihood ratio were calculated. Chi-square and Fisher exact test were used to evaluate relationships between PCT results and maximal urine flow (Qmax); a p<0.05 was considered statistically significant.

RESULTS

The mean (±standard deviation) age of the study group was 65.5±10.4 years. Overall, by use of the PCT, 24 patients were diagnosed as being obstructed and 27 patients as unobstructed. At the subsequent PFS, 16 of the 24 patients diagnosed as obstructed by the PCT were confirmed to be obstructed, 4 were diagnosed as unobstructed, and the remaining 4 patients appeared equivocal. Of the 27 patients shown to be unobstructed by the PCT, 25 were confirmed to not be obstructed by PFS, with 13 equivocal and 12 unobstructed. Two patients were diagnosed as being obstructed. For detecting obstruction, the PCT showed an SE of 88.9% and an SP of 75.7%. The PPV was 66.7% and the NPV was 93%.

CONCLUSIONS

The PCT is a beneficial test for evaluating patients with LUTS. In particular, this instrument has an acceptable ability to reject obstruction caused by benign prostatic hyperplasia.

Correlation between penile cuff test and pressure-flow study in patients candidates for trans-urethral resection of prostate

Background

Aim of this study was to make a comparison between penile cuff test (PCT) and standard pressure-flow study (PFS) in the preoperative evaluation of patients candidates for trans-urethral resection of prostate (TURP) for benign prostatic obstruction (BPO).

Methods

We enrolled male patients with lower urinary tract symptoms candidates for TURP. Each of them underwent a PCT and a subsequent PFS. A statistical analysis was performed: sensitivity (SE), specificity (SP), positive predictive value (PPV), negative predictive value (NPV), likelihood ratio and ratio of corrected classified were calculated. Fisher exact test was used to evaluate relationships between PCT and maximal urine flow (Q_max): a p-value < 0.05 was considered statistically significant.

Results

We enrolled 48 consecutive patients. Overall, at PCT 31 patients were diagnosed as obstructed and 17 patients as unobstructed. At the subsequent PFS, 21 out of 31 patients diagnosed as obstructed at PCT were confirmed to be obstructed; one was diagnosed as unobstructed; the remaining 9 patients appeared as equivocal. Concerning the 17 patients unobstructed at PCT, all of them were confirmed not to be obstructed at PFS, with 10 equivocal and 7 unobstructed. The rate of correctly classified patients at PCT was 79% (95%-CI 65%-90%). About detecting obstructed patients, PCT showed a SE of 100% and a SP of 63%. The PPV was 68%, while the NPV was 100%.

Conclusions

PCT can be an efficient tool in evaluating patients candidates for TURP. In particular, it showed good reliability in ruling out BPO because of its high NPV, with a high rate of correctly classified patients overall. Further studies on a huger number of patients are needed, including post-operative follow-up as well.

The accuracy of three-dimensional bladder ultrasonography in determining the residual urinary volume compared with conventional catheterisation

Objective

To determine the accuracy of three-dimensional bladder ultrasonography (US, using the BVI 3000, Verathon, WA, USA) for determining the residual urinary volume, compared with the conventional catheterisation method.

Patients and methods

We conducted a cross-sectional study at day-care unit of a University hospital after obtaining approval from the Ethics Review Committee of the hospital. Thirty-four patients with lower urinary tract symptoms requiring cystometrography were included. The postvoid volume was measured by bladder US, with three readings taken, and then patient was catheterised using a 12-F Nelaton catheter to measure the urinary volume. The mean of the three readings was compared with the catheterisation volume.

Results

The mean (SD) urinary volumes by US and catheterisation were 261 (186) and 260 (175) mL, respectively, and the correlation (r²) was 0.97. There was no effect of age, gender or body mass index on the accuracy of bladder US, which was accurate even when the urinary volume was ⩽100 mL.

Conclusion

The bladder US estimate is as accurate as catheterisation for determining the postvoid residual urinary volume. Its accuracy was also comparable when the urinary volume is <100 mL, and there was no significant effect of age, gender and body mass index. This system could replace the more invasive catheterisation, and with excellent accuracy.

Voiding dysfunction due to detrusor underactivity: an overview

Detrusor underactivity (DUA) is defined as a voiding contraction of reduced strength and/or duration, which prolongs urination and/or prevents complete emptying of the bladder within a 'normal' period of time. This issue is associated with voiding and postmicturition urinary symptoms, and can predispose to urinary infections and acute urinary retention. The aetiology of DUA is influenced by multiple factors, including ageing, bladder outlet obstruction, neurological disease, and autonomic denervation. The true prevalence of this condition remains unknown, as most data come from referral populations. Urodynamic testing is used to diagnose the condition, either by assessing the relationship between bladder pressures and urinary flow, or by interrupting voiding to measure detrusor pressure change under isovolumetric conditions. Current treatments for DUA have poor efficacy and tolerability, and often fail to improve quality of life; muscarinic receptor agonists, in particular, have limited efficacy and frequent adverse effects. Bladder emptying might be achieved through Valsalva straining, and intermittent or indwelling catheterization, although sacral nerve stimulation can reduce dependency on catheterization. Novel stem-cell-based therapies have been attempted; however, new drugs that increase contractility are currently largely conceptual, and the complex pathophysiology of DUA, difficulty achieving organ specificity of treatment, the limited availability of animal models, and the subjective nature of current outcome measures must be addressed to facilitate the development of such agents.

Detrusor underactivity and the underactive bladder: a new clinical entity? A review of current terminology, definitions, epidemiology, aetiology, and diagnosis

CONTEXT

Detrusor underactivity (DU) is a common cause of lower urinary tract symptoms (LUTS) in both men and women, yet is poorly understood and underresearched.

OBJECTIVE

To review the current terminology, definitions, and diagnostic criteria in use, along with the epidemiology and aetiology of DU, as a basis for building a consensus on the standardisation of current concepts.

EVIDENCE ACQUISITION

The Medline and Embase databases were searched for original articles and reviews in the English language pertaining to DU. Search terms included underactive bladder, detrusor underactivity, impaired detrusor contractility, acontractile detrusor, detrusor failure, detrusor areflexia, raised PVR [postvoid residual], and urinary retention. Selected studies were assessed for content relating to DU.

EVIDENCE SYNTHESIS

A wide range of terminology is applied in contemporary usage. The only term defined by the standardisation document of the International Continence Society (ICS) in 2002 was the urodynamic term detrusor underactivity along with detrusor acontractility. The ICS definition provides a framework, considering the urodynamic abnormality of contraction and how this affects voiding; however, this is necessarily limited. DU is present in 9-48% of men and 12-45% of older women undergoing urodynamic evaluation for non-neurogenic LUTS. Multiple aetiologies are implicated, affecting myogenic function and neural control mechanisms, as well as the efferent and afferent innervations. Diagnostic criteria are based on urodynamic approximations relating to bladder contractility such as maximum flow rate and detrusor pressure at maximum flow. Other estimates rely on mathematical formulas to calculate isovolumetric contractility indexes or urodynamic "stop tests." Most methods have major disadvantages or are as yet poorly validated. Contraction strength is only one aspect of bladder voiding function. The others are the speed and persistence of the contraction.

CONCLUSIONS

The term detrusor underactivity and its associated symptoms and signs remain surrounded by ambiguity and confusion with a lack of accepted terminology, definition, and diagnostic methods and criteria. There is a need to reach a consensus on these aspects to allow standardisation of the literature and the development of optimal management approaches.

A novel method for monitoring urinary bladder internal pressure: feasibility test

The study presents a new approach for measuring non-invasively urinary bladder internal pressure which can resolve all the shortcomings of existing methods. The novel method makes use of acoustic cavitation. The theoretical foundation for the proposed technique was presented, together with the preliminary experimental validation. The study claims that the proposed novel non-invasive ultrasonic urinary bladder internal pressure monitoring is feasible and can be used any time regardless of gender, so that it will be of a great benefit to the diagnosis and therapy of urination related diseases.

A novel intraurethral device diagnostic index to classify bladder outlet obstruction in men with lower urinary tract symptoms

Objectives. Using a urethral device at the fossa navicularis, bladder pressure during voiding can be estimated by a minimal invasive technique. This study purposes a new diagnostic index for patients with lower urinary tract symptoms (LUTSs). Methods. Fifty one patients presenting with LUTSs were submitted to a conventional urodynamic and a minimal invasive study. The results obtained through the urethral device and invasive classic urodynamics were compared. The existing bladder outlet obstruction index (BOOI) equation that classifies men with LUTSs was modified to allow minimal invasive measurement of isovolumetric bladder pressure in place of detrusor pressure at maximum urine flow. Accuracy of the new equation for classifying obstruction was then tested in this group of men. Results. The modified equation identified men with obstruction with a positive predictive value of 68% and a negative predictive value of 70%, with an overall accuracy of 70%. Conclusions. The proposed equation can accurately classify over 70% of men without resorting to invasive pressure flow studies. We must now evaluate the usefulness of this classification for the surgical treatment of men with LUTSs.

New method for minimally invasive urodynamic assessment in men with lower urinary tract symptoms

OBJECTIVES

Urodynamic studies are considered the reference standard to diagnose bladder outlet obstruction. However, the procedure is invasive, expensive, and time-consuming. The purpose of this study was to evaluate a new minimally invasive urodynamic assessment model and compare the results with those of conventional urodynamic evaluation.

METHODS

The study included 50 male patients who presented with lower urinary tract symptoms. Their mean age was 62 years (range 34 to 82). After undergoing a conventional urodynamic study, they underwent the minimally invasive evaluation. The urethral device is a conical apparatus that adapts to the urethral meatus and fossa navicularis. The isometric bladder pressure and interrupted flow were recorded. The results of the conventional assessment were classified according to the Abrams-Griffiths number and a logistic regression fit was applied to the minimally invasive method.

RESULTS

Only two variables demonstrated the predictive capacity: the isometric pressure and interrupted flow. In addition to selecting the relevant variables, logistic regression analysis is a more adequate model that provides a binary result of obstructed and unobstructed, used to predict the normal and equivocal categories of the Abrams-Griffiths classification, and taken as the reference standard. The sensitivity and specificity of the new method was 67% and 79%, respectively.

CONCLUSIONS

The urethral device proved to be simple and easy to use. The minimally invasive method was able to detect most patients with bladder outlet obstruction; thus, the conventional urodynamic assessment could be avoided. We consider this method to have a place as a first-line noninvasive examination.

Noninvasive methods of diagnosing bladder outlet obstruction in men. Part 2: Noninvasive urodynamics and combination of measures

PURPOSE

Many methods have been suggested to diagnose bladder outlet obstruction, as defined by the gold standard of pressure flow studies. Difficulty arises when comparing completely different methods of diagnosing bladder outlet obstruction. A comprehensive review of the literature on the different methods used to diagnose bladder outlet obstruction by noninvasive means was performed with a view to allow such a comparison.

MATERIALS AND METHODS

A MEDLINE search was done of the published literature covering until the end of 2004 on noninvasive methods, including single measure and combinations of measures, to diagnose bladder outlet obstruction. A direct comparison of all of the different methods was made using the sensitivity, specificity, likelihood ratio, and pretest and posttest probability of diagnosing bladder outlet obstruction for each test. For many techniques these values were calculated from the data presented in the article.

RESULTS

A multitude of methods has been applied to diagnose bladder outlet obstruction. Broadly the methods were divided into nonurodynamic and noninvasive urodynamic methods. Nonurodynamic methods were considered in part 1 of the review. Part 2 considered noninvasive urodynamic techniques, such as uroflowmetry, the penile cuff, the condom method and Doppler urodynamics. A combination of single measures was also considered and the relative merits of these approaches were discussed.

CONCLUSIONS

A combination of noninvasive urodynamics and ultrasound derived measures provide promising methods of diagnosing bladder outlet obstruction. However, pressure flow studies still remain the gold standard for assessing bladder outlet obstruction.