Resistive Index as Risk Factor for Acute Urinary Retention in Patients With Benign Prostatic Hyperplasia

Recent developments in diagnostic ultrasound for lower urinary tract function

Ultrasonography (US) is an essential tool in the clinical management of lower urinary tract dysfunction (LUTD), including lower urinary tract symptoms, overactive bladder, and benign prostatic hyperplasia, in which prostatic volume and post-void residual volume are routinely used to evaluate the pathophysiological characteristics of afflicted patients. US can also be employed to diagnose hydronephrosis and bladder calculus as complications of severe LUTD. Moreover, US is essential for identifying pathophysiological characteristics and surgical indications, predicting disease development and drug efficacy, and monitoring bladder function improvement by means of such parameters as bladder wall thickness, prostatic urethral length, intravesical prostatic protrusion, and prostatic urethral angulation/angle. Herein, I narratively review the recent advances in US approaches for the management of LUTD, especially in adult males.

Day Temperature Difference and Aggravation of Low Urinary Tract Symptom in Benign Prostate Hypertrophy Patients in Korea: A National Health Insurance Service-National Cohort-based Study

OBJECTIVE

To investigate the symptom deterioration of patients with benign prostatic hyperplasia (BPH) according to the difference in daily temperature.

PATIENTS AND METHODS

From the National Health Insurance Service database, we collected and analyzed data on patients with BPH in 6 major metropolitan areas in Korea between January 2008 and December 2017. We investigated the rate of emergency room visits as well as the rate of urethral catheter insertion.

RESULTS

In total, 1,446,465 patients were enrolled in this study. When the daily temperature difference was below 4°C, 28.5 patients visited the emergency room daily, while 42.2 patients visited the emergency room daily when the daily temperature difference exceeded 14°C. When the daily temperature difference was more than 14°C, about 48.0% more patients visited the emergency room than when the daily temperature difference was below 4°C. After visiting the emergency room, there were 11.9 patients who had a catheter inserted daily at the daily temperature difference below 4°C. When the daily temperature difference was more than 14°C, the number of catheter insertion cases was 17.8 patients daily, which was 49.2% higher than that of below 4°C. By time, surgery was performed most frequently within 3 months after visiting the emergency room.

CONCLUSION

Day temperature difference appear to be related to the Lower urinary tract symptom of BPH patients.

Evaluation of resistive index of the prostate and bladder sonomorphologic parameters as replacements for urodynamics to predict bladder outlet obstruction in patients with lower urinary tract symptoms suggestive of benign prostatic hyperplasia

OBJECTIVE

This study investigated whether the resistive index (RI) of prostate and bladder sonomorphologic parameters (total prostate volume [TPV], detrusor wall thickness [DWT], intraprostatic protrusion [IPP]) can be used instead of urodynamic studies (UDS) to predict bladder outlet obstruction (BOO) in benign prostatic hyperplasia (BPH) with lower urinary tract symptoms (LUTS).

METHODS

Men aged ≥50 years with clinical BPH/LUTS were prospectively enrolled included. Basic evaluations, measurement of sonomorphologic parameters, and UDS were performed in accordance with the International Continence Society's Good Urodynamics Practices protocol.

RESULTS

Data of 240 patients were divided into two groups based on the BOO index(BOOI). Group 1 consisted of patients negative for BOO (BOOI <40), whereas Group 2 consisted of patients positive for BOO (BOOI > 40). Patient age, International Prostate Symptom Score (IPSS), quality of life score and post-void residual volume were comparable between the two groups, whereas significant differences were evident in peak flow rate, TPV, DWT, RI, and IPP (P < 0.01 for all). Pearson correlation analysis revealed a significant correlation between BOOI and DWT (r = 0.198, P = 0.002), IPP (r = 0.450, P = 0.000), and RI (r = 0.334, P = 0.000). Multiple regression analysis revealed a significant correlation between BOOI and IPP (β = 0.382, P = 0.000) and RI (β = 0.226, P = 0.000). Receiver operating characteristic analysis showed that the area under curve was 0.785 for RI (95% confidence interval [CI] 0.703-0.867, P < 0.001) and 0.905 for IPP (95% CI 0.850-0.961, P < 0.001). At a cut-off value of 7.5 mm for IPP, the sensitivity was 86.9%, specificity was 83.3% and positive predictive value was 92.41%.

CONCLUSION

IPP and RI may be the best non-invasive predictors for BOO in selected patients with LUTS/BPH.

Non-invasive evaluation of lower urinary tract symptoms (LUTS) in men

Lower urinary tract symptoms (LUTS) are common in males over the age of 40 years old and are likely to increase with an aging population. Currently urodynamic studies are the gold standard to determine the aetiology of voiding dysfunction and LUTS. However, due to its invasive nature, a great number of non-invasive ultrasound based investigations have been developed to assess patients with symptomatic LUTS. The clinical application of non-invasive tests could potentially stratify patients who would require more invasive investigations and allow more precise patient directed treatment. A PubMed literature review was performed and we will discuss the non-invasive investigations that have been developed thus far, focusing on bladder wall and detrusor wall thickness (BWT & DWT), ultrasound estimated bladder weight (UEBW) and intravesical prostatic protrusion (IPP).

Association of Prostate Blood Flow with Male Lower Urinary Tract Symptoms

PURPOSE

To investigate the association of prostate blood flow (PBF) with lower urinary tract symptoms (LUTS) in aged males using Doppler spectral waveform (DSW) analysis.

PATIENTS AND METHODS

We performed a prospective analysis involving 133 aged males with clinical diagnosis of LUTS. DSW parameters (peak-systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI)) were measured at bilateral neurovascular bundles (NVB), periurethral, and capsular branches by Doppler transrectal ultrasound with the patient in the right lateral decubitus position. The associations of PBF parameters and the International Prostate Symptom Score (IPSS) were analyzed.

RESULTS

Overall, total IPSS scores were significantly correlated with the RI of bilateral NVB vessels (r2 = 0.03, 0.04; p = 0.04, 0.02, respectively), and PSV of left NVB vessels. PSV of bilateral NVB vessels were associated with the storage score (p = 0.022 and p = 0.016), but not with the voiding score. The sum of the frequency and urgency score was also associated with EDV of both capsular and urethral branches (p = 0.043 and p = 0.009, respectively), and PSV of NVB vessels on both sides (p = 0.045 and p = 0.019, respectively).

CONCLUSIONS

There is an association between PBF and LUTS, especially with storage symptoms. The findings may provide some insights in understanding the underlying pathophysiology of lower urinary tract dysfunction.

The use of imaging techniques in understanding lower urinary tract (dys)function

The ability to store urine in the bladder and to void at an appropriate time depends on several complex mechanisms in the lower urinary tract (LUT) and its neural control. Normal LUT function requires coordination of the urinary bladder, urethra, pelvic floor, efferent and afferent neurons and specific spinal cord and brain areas. These structures can be visualised using different imaging modalities, such as ultrasound, X-ray and magnetic resonance imaging. The supraspinal neural control of the LUT can be studied using functional brain imaging. During the last two decades, the many technological improvements of these imaging techniques have increased our knowledge of voiding dysfunction. Here, we review the different imaging modalities of the LUT and its neural control and discuss their importance for diagnosing and understanding voiding dysfunction.

Implication of ultrasound bladder parameters on treatment response in patients with benign prostatic hyperplasia under medical management

OBJECTIVE

The prevalence of benign prostatic hyperplasia (BPH) rapidly increases after the 4th decade of life. The combination of tamsulosin and dutasteride is a well established therapy for BPH of ≥40 g. Non-invasive urodynamic parameters can predict the outcome of medical therapy in patients with BPH. We aimed to correlate these parameters with treatment responses in BPH patients under medical management.

METHODS

A prospective study was conducted in the Department of Urology in our hospital from May 2014 to April 2015. A total of 100 patients with BPH ≥40 g who fulfilled our inclusion criteria were included. Treatment responses were determined by the International Prostate Symptom Score (IPSS) and uroflowmetry. Transabdominal ultrasonography with Doppler was performed to measure prostate volume, intravesical prostatic protrusion (IPP), detrusor wall thickness (DWT), the prostatic capsular artery resistive index (RI) and prostatic urethral angle (PUA) before and 3 months after combination therapy of tamsulosin and dutasteride. Treatment responses were correlated with non-invasive urodynamic parameters.

RESULTS

The IPSS, uroflow, age, prostate volume, RI, IPP, DWT and PUA were correlated before and after treatment. Of the 100 patients, 70 (70%) showed significant improvement and 30 (30%) showed no improvement with therapy.

CONCLUSION

Ultrasound bladder parameters are useful tools for measuring the treatment response in BPH patients. Our study shows that RI and DWT significantly correlate with the treatment response in BPH patients. More importantly, pretreatment values of increased IPP and PUA determines the non-improvement of symptoms in BPH patients. Our study suggests the importance of transabdominal ultrasonography (KUB-P) with Doppler for evaluating treatment responses to medical management.

Predicting Acute Urinary Retention in Patients with Elevated Post-Void Residuals

OBJECTIVES

To perform a retrospective analysis evaluating factors that may predict which men with elevated post-void residuals (PVRs) that were at increased risk to develop acute urinary retention (AUR).

METHODS

We retrospectively analyzed the records of 44 male patients who had 2 consecutive PVRs greater than 100 ml over a 6-month period. Using regression analysis, we evaluated patient's age, PVR volume, prostate specific antigen (PSA) and transrectal ultrasound prostate volume with respect to development of AUR over 24 months.

RESULTS

Of the 44 patients, 4 developed AUR. When all factors were considered, prostate volume was determined to be the only that was statistically significant (p = 0.003). A 1-SD increase in prostate volume (12 ml) led to a 19.6% increased risk of developing AUR. There was a strong correlation between PSA and prostate volume (0.787). A regression analysis was then repeated excluding prostate volume. PSA then became a statistically significant predictor of AUR (p = 0.007). A 1-SD increase in PSA (1.377 ng/ml) increased the patients' risk of developing AUR by 12.3%.

CONCLUSION

In men with an elevated PVR, increased transrectal ultrasound prostate volume or PSA may help predict which patients have an elevated risk of developing AUR within the next 24 months. This information may influence which patients need early surgical intervention versus medical therapy.

Establishment and value assessment of efficacy prediction model about transurethral prostatectomy

OBJECTIVES

To establish and to evaluate discriminant models to predict the outcomes of transurethral prostatectomy.

METHODS

Clinical data of patients treated with transurethral prostatectomy between January and December 2013 were collected, including medical history, symptoms, biochemical tests, ultrasonography and urodynamics. Surgical efficacy was evaluated at 6-month follow up. Predictive models were constructed by logistic regression. Receiver operating characteristic curve and diagnostic tests were used to test the accuracy of models before the predictive value between models was compared.

RESULTS

A total of 182 patients were included, with 73.6% having an effective outcome. History of recurrent urinary tract infection (OR 1.33), score of storage phase (OR 2.58), maximum flow rate (OR 2.11) and detrusor overactivity (OR 3.13) were found to be risk factors. International Prostate Symptom Score (OR 0.13), transitional zone index (OR 0.58), resistive index of prostatic artery (OR 0.46), bladder wall thickness (OR 0.78), ultrasonic estimation of bladder weight (OR 0.28), bladder outlet obstruction index (OR 0.20) and bladder contractility index (OR 0.83) were found to be protective factors. The areas under the curve of models using factors from ultrasonography and urodynamics were 0.792 and 0.829 respectively, with no significant difference being found between them (P = 0.348).

CONCLUSIONS

Surgical efficacy of transurethral prostatectomy is positively correlated to severe voiding phase symptoms, outlet obstruction and better detrusor contractility, and negative correlated with urinary infection, severe storage phase symptoms and excessive detrusor contractibility. Ultrasonography might replace urodynamics in selecting patients for whom transurethral prostatectomy is more likely to be beneficial.

The role of intravesical prostatic protrusion (IPP) in the evaluation and treatment of bladder outlet obstruction (BOO)

AIMS

Intravesical prostatic protrusion (IPP) may be an underutilized modality for the assessment of bladder outlet obstruction (BOO). Pressure flow studies or urodynamics have long been the gold standard for the evaluation of lower urinary tract symptoms (LUTS) in men but are invasive, time-consuming and costly. Potentially, IPP may be a useful adjunct prior to performing urodynamics.

METHODS

Measurement of IPP is taken in the sagittal view, using the transabdominal ultrasound. It is the vertical height from the tip of the protrusion to the base of the prostate. This technique was previously described. We reviewed previous publications that studied the accuracy, positive predictive value and clinical use of IPP. In addition, we noted the comments regarding the challenges of using this technique.

RESULTS

IPP has been shown to have a positive predictive value of 72% for BOO. It has been calculated to have an area under curve (AUC) value of 0.71 and 0.84 in some stuies. Clinically, it may be used to predict the outcome of a trial without catheter following acute retention of urine. Patients with higher IPP grade were noted to have a higher risk of clinical progression. Studies have also shown that men with higher IPP are poorer responders to medical treatment such as α-blockers.

CONCLUSIONS

Compared to other modalities, the advantage of IPP in assessing BOO may be its easy applicability and non-invasive nature. Therefore, there is a consideration for a larger role of IPP in bedside assessment and management of BOO in daily practice. Neurourol. Urodynam. 35:535-537, 2016. © 2015 Wiley Periodicals, Inc.

Resistive index of prostatic capsular arteries as a predictor of prostate cancer in patients undergoing initial prostate biopsy

To evaluate the value of resistive index (RI) of prostatic capsular arteries in diagnosis and evaluation of prostate cancer (PCa) in Chinese patients undergoing initial prostate biopsy. A total of 532 consecutive patients undergoing prostate biopsy were enrolled in this study. RI was measured on the largest transverse section of prostate for each individual. The predictive value of RI was evaluated using multivariate logistic regression and receiver operating characteristic (ROC) curve analyses. PCa was identified in 217 (40.79%) patients. RI was 0.69 ± 0.08 and 0.8 ± 0.08 for patients without and with PCa (p < 0.01). On logistic regression RI was significantly associated with PCa (p < 0.01). Using ROC analysis RI outperformed tPSA in prediction of PCa in all patients [area under ROC curve (AUC) = 0.83, 0.78, respectively]. With the cutoff value of 0.73, RI discriminated PCa from non-PCa patients with 81.9% sensitivity, 75.9% specificity and 77.63% diagnostic accuracy. Furthermore, The AUC for RI in the discrimination of PCa from non-PCa patients in a subset with PSA of 4 to 10 ng/ml, high grade from non-high grade PCa patients and advanced from localized PCa patients was 0.70, 0.77 and 0.80, higher than other parameters (p < 0.05). RI is proved a practicable parameter in identifying patients at risk for PCa and predicting the grade and stage of PCa before initial prostate biopsy. The value of RI should be further explored in the future.

How antepartum and postpartum acute urinary retention affects the function and structure of the rat bladder

INTRODUCTION AND HYPOTHESIS

To examine the effect of acute urinary retention (AUR) on the urodynamic function and molecular structure of rat bladders in pregnancy and after parturition.

METHODS

Forty-eight nulliparous rats were distributed into AUR and non-AUR groups. AUR was induced by clamping the distal urethra of each rat after infusing 3 ml of saline for 60 min. Plasma progesterone levels and cystometric data were evaluated on the 14th day of gestation, 3 and 10 days postpartum, and in virgin rats. The immunoreactivity of caveolins and nerve growth factor (NGF) was analyzed. The number of caveolae in bladder muscle cells was evaluated by electron microscopy.

RESULTS

Progesterone levels significantly increased during pregnancy and 3 days postpartum. In cystometric results, the AUR group has significantly shorter intercontraction interval, lower void volume and greater residual volume compared with the non-AUR. AUR rats exhibited higher NGF immunoreactivity, lower caveolin-1 immunoreactivity, and less caveolae in the bladder compared with the non-AUR. The caveolin-1 and NGF immunoreactivity and the number of caveolae in the bladder decreased during pregnancy and 3 days postpartum compared with virgin rats. By using Pearson correlations, we found significant correlations between urodynamic variables (residual volumes and intercontraction intervals) and the expressions of caveolin-1, caveolae and NGF in the AUR rats on the 14th day of gestation and 3 days postpartum.

CONCLUSIONS

Bladder dysfunction in pregnancy and immediately postpartum in a rat model caused by AUR is associated with the plasma progesterone level change and the expressions of caveolin, caveolae, and NGF in bladder muscle cells.

Evaluation of the resistive index of prostatic blood flow in benign prostatic hyperplasia

OBJECTIVE

The aim of this work is to study the resistive index (RI) of prostatic blood flow by transrectal power Doppler sonography in benign prostatic hyperplasia (BPH) to determine its correlation with other parameters of BPH.

MATERIALS AND METHODS

Eighty-two male patients aged 52-86 years with lower urinary tract symptoms (LUTS) due to BPH were included in the study. Patients with prostate cancer, neurogenic bladder, or with other pathology (e.g. prostatitis, bladder stone) were excluded from the study. All patients were evaluated by full history including Internatinoal Prostate Symptoms Score (IPSS), general and local examination (DRE), neurologic examination, uroflowmetry, laboratory investigations including urine analysis, routine laboratory tests and serum prostate specific antigen (PSA). Transrectal ultrasonography was used to calculate the total prostatic volume. Transrectal Power Doppler Ultrasound (PUD) was used to identify the capsular and urethral arteries of the prostate and to measures the RI value.

RESULTS

The mean prostate volume was 75.1 ± 44.7 g. The mean RI of the right and left capsular arteries were 0.76 ± 0.06 and 0.76 ± 0.07, respectively. The mean RI of the urethral arteries was 0.76 ± 0.08. There was a high significative correlation between the increase of the RI of the right and left capsular and urethral arteries and the degree of obstruction (P value < 0.001), severity of symptoms (P value < 0.001) and also the prostatic volume (P value < 0.001).

CONCLUSION

Resistive index of the prostatic blood flow can be applied as an easy and non-invasive tool to evaluate the lower urinary tract obstruction due to BPH.

Intravesical residual urine of patients with benign prostate hyperplasia, sonography accuracy

Measurement of intravesical residual urine is experimentally a diagnostic, therapeutic and follow-up criterion in patients with benign prostate hyperplasia. The study aims at evaluating sonography accuracy in measuring intravesical residual urine in comparison with standard and accurate way of measurement through bladder catheterization. The study was conducted on 60 patients hospitalized for benign prostate hyperplasia. Mean age of the patients was 67.10 +/- 8.33 years. In all patients with full bladder and after urination, the post void residue was initially measured by sonography at supine position and then immediately through bladder catheterization. This study evaluated 60 patients with mean age of 67.10 +/- 8.33 years. The difference between measuring through sonography and catheterization was 7.89 +/- 0.86, 14.46 +/- 1.87 and 32.73 +/- 2.99 mL in postvoid residue less than 50, 51-100 and more than 100 mL, respectively. In patients with benign prostate hyperplasia, transabdominal sonography is a non-invasive method to determine postvoid residue amount.

Imaging in benign prostatic hyperplasia: what is new?

PURPOSE OF REVIEW

This article discusses the new imaging techniques in diagnosis and treatment of benign prostatic hyperplasia by reviewing the most recent publications.

RECENT FINDINGS

Imaging study for the evaluation of patients with lower urinary tract symptoms is not suggested by American Urology Association guidelines; however, European Association of Urology recommends the assessment of the upper urinary tract by modalities like ultrasound. Several new imaging indices like resistive index of capsular artery, presumed circle area ratio, prostatic urethral angle, intraprostatic protrusion, and detrusor wall thickness are used to find a noninvasive way for bladder outlet obstruction diagnosis. In addition to them, 3D transrectal ultrasound, near infrared spectroscopy, and MRI are used to add more practical findings in patient management.

SUMMARY

Urologists have requested more imaging studies than expected for benign prostatic hyperplasia patients in recent years, and several studies have been done to find a noninvasive way to diagnose bladder outlet obstruction. However, none of them could play the urodynamic studies role in bladder outlet obstruction diagnosis.

Office evaluation of male patients with lower urinary tract symptoms

Lower urinary tract symptoms due to benign prostatic hyperplasia (LUTS/BPH) are one of the most common urologic disorders in men. Accurate history-taking and focused physical examination allows us to diagnose the majority of cases. A better understanding of risk factors helps us tailor our treatment and predict outcomes more accurately. Population studies are crucial in our understanding of LUTS/BPH natural history. Temporary prostatic urethral stents that are used for the management of urinary retention may also be used for evaluation of patients with detrusor hypo-contractility. The use of ultrasound to measure intravesical prostatic protrusion (IPP) and the Doppler study for prostate capsular artery resistive index are promising. Near-infrared spectroscopy (NIRS) examines the tissue oxygenation that may be affected by bladder outlet obstruction. The mathematical algorithm needs some fine-tuning, and its reproducibility is debatable. Serum and urinary biomarkers may help us to diagnose the disorder, and more effectively monitor patients' response to therapy. Among all, IPP is clinically more applicable at this time.

Utility of the transition zone index for identification of prostate cancer in Chinese men with intermediate PSA levels

PURPOSE

We aimed to investigate the utility of the transition zone index (TZI) for identification of prostate cancer (PCa) in Chinese men with prostate-specific antigen (PSA) levels of 4-10 ng/mL.

METHODS

In this retrospective cohort study, results of transrectal ultrasonography (TRUS)-guided biopsy were assessed in 616 consecutive Chinese men; all subjects had intermediate serum PSA levels and normal digital rectal examination findings. The prostate and transition zone volumes were determined by TRUS. A TZI cutoff value of 0.47 produced the best sensitivity and specificity rates in receiver operating characteristic (ROC) curve analysis and thus was used to classify the study subjects into two subgroups: group 1 with TZI ≤ 0.47 and group 2 with TZI > 0.47. Logistic regression analysis was used to predict outcomes. The variables that were statistically significant in the stepwise logistic regression analysis were assessed using the ROC curve and the area under the curve.

RESULTS

Overall, 166 of the 616 patients (26.9%) had histologically confirmed PCa. A total of 238 (38.6%) patients were classified into group 1, of whom 97 (40.8%) exhibited a positive biopsy; and 378 (61.4%) patients were classified into group 2, of whom 69 (18.3%) exhibited a positive biopsy. The stepwise logistic regression analysis revealed that PSA density (PSAD) exhibited the strongest predictive value in the overall population and in group 1, whereas PSA transition zone density (PSATZD) was the optimal predictor in group 2. The ROC curve analysis revealed that when using the TZI-specific 100% sensitivity cutoffs, 17.7% and 25% of the biopsies were unnecessary and could be avoided in the overall patient population prior to and following the division into groups, respectively (P = 0.002). Using an individually generated 95% sensitivity cutoff of 0.12 ng/mL(2) for PSAD and a cutoff of 0.179 ng/mL(2) for PSATZD for TZI-stratified cohorts of TZI ≤ 0.47 and TZI > 0.47, a more consistent specificity of 44% and 46.9%, respectively, for each cohort was observed.

CONCLUSIONS

The optimal predictor for PCa differs between various TZI levels. The combination of PSAD in patients with TZI ≤ 0.47 and PSATZD in patients with TZI > 0.47 helps to identify potentially unnecessary biopsies compared to the use of a single PSAD for the entire patient population. The discrepancies regarding an optimal predictor in published reports are most likely due to the differing TZI levels among the cases. In this study, we demonstrated improved identification of PCa using TZI-adjusted cutoffs for PSAD and PSATZD.

Application of ultrasonography and the resistive index for evaluating bladder outlet obstruction in patients with benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is an extremely common and chronic condition that can lead to bladder outlet obstruction (BOO) in elderly men. Although pressure-flow studies are considered the most reliable method for evaluating BOO, they are invasive and complicated. Transrectal ultrasonography (TRUS) is a promising alternative because of its minimal invasiveness. Recently, TRUS imaging has been shown capable of measuring the resistive index, a useful parameter for evaluating BOO and for determining proper medical intervention in patients suffering from BPH.