Color doppler ultrasonography: Its role in detection and treatment outcome in infravesical obstruction

Saleem Wani; Arif Hamid; M Gopi Kishore; Vibhav Malviya; US Dwivedi; PB Singh

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RESEARCH ARTICLE

Year : 2003 \| Volume : 19 \| Issue : 2 \| Page : 109-112

Color doppler ultrasonography: Its role in detection and treatment outcome in infravesical obstruction

Saleem Wani, Arif Hamid, M Gopi Kishore, Vibhav Malviya, US Dwivedi, PB Singh
Department of Urology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India

Correspondence Address:
P B Singh
Department of Urology, Institute of Medical Sciences, Banaras Hindu University, Varanasi - 221 005
India

Source of Support: None, Conflict of Interest: None

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Abstract

Bladder weight and detrusor blood perfusion increases significantly with infravesical obstruction (IVO) and release of obstruction results in reduction of bladder weight and detrusor blood flow. 38 patients with IVO were subjected to color Doppler ultrasonography (CD U) to detect the blood flow in the hypertrophied detrusor muscle. Blood flow was detected in 84.5% (Fisher exact probability <0.001). After surgical relief of obstruction, blood flow remained positive in 21.05% patients at 3 months and 13.10% patients at 6 months, which was because of persistence of IVO. Color Doppler ultrasonography (CDU) is a simple and non-invasive tool which can help in diagnosis and follow-up of infravesical obstruction.

Keywords: Color Doppler ultrasonography. ultrasound evaluated bladder weight. infravesical obstruction.

How to cite this article:
Wani S, Hamid A, Kishore M G, Malviya V, Dwivedi U S, Singh P B. Color doppler ultrasonography: Its role in detection and treatment outcome in infravesical obstruction. Indian J Urol 2003;19:109-12

How to cite this URL:
Wani S, Hamid A, Kishore M G, Malviya V, Dwivedi U S, Singh P B. Color doppler ultrasonography: Its role in detection and treatment outcome in infravesical obstruction. Indian J Urol [serial online] 2003 [cited 2021 Jun 25];19:109-12. Available from: https://www.indianjurol.com/text.asp?2003/19/2/109/37139

Introduction

It is a well-known fact that infravesical obstruction is followed by compensatory hypertrophy and increase in blood perfusion of the detrusor muscle in the human and animal urinary bladder. Release of obstruction leads to decrease in this compensatory hypertrophy as well as blood flow as shown by animal studies.^[1],[2] However, due to lack of non-invasive investigative tools, these changes have not been demonstrated in human bladders, and the urodynamic studies still remain the `gold standard' for diagnosis of the IVO. Assessment of the weight by ultrasound (UEBW = ultrasound evaluated bladder weight) has been shown to be a sensitive and non-invasive tool for assessing the infravesical obstruction.^[3],[4] Remarkable improvements in the color Doppler ultrasonography has made it possible to detect the blood flow non-invasively and accurately in the hypertrophied detrusor resulting from the IVO.^[5] The present study was undertaken to assess the applicability of CDU in detecting, quantifying and monitoring the detrusor changes resulting from IVO.

Patients and Methods

Between July 1999 and October 2000, 38 patients with IVO and 10 control cases without any lower urinary tract symptoms were included in the study (benign prostatic hyperplasia - 16, stricture urethra - 9, bladder neck obstruction - 6, meatal stenosis - 7). Besides routine baseline investigations, uroflowmetry (UFM) was done in all the patients and voided volume, voiding time and peak flow rate (PFR) were recorded. Cystourethroscopy was done in all the patients and RGU and MCU in selected patients. All the patients were screened on GE LOGIC 400 CL color Doppler equipment using 3.5 and 7.5 MHz transducer probes, with a partially full bladder with approximate volume of 100 ml. Assuming the bladder to be a sphere, UEBW was calculated as under:^[6]

Bladder wall thickness (T); Inner diameter (ID); Outer diameter (OD); Intravesical volume (IV); and total vesical volume (TV) were determined. Sequentially, the volume of the bladder wall (BV) was obtained by subtracting the IV from TV and the UEBW was calculated by multiplying the BV by specific gravity (1.0), [Figure - 1].

BV = TV-IV

IV= Sagittal height x Sagittal depth x 6.6

UEBW = BV x Sp. gravity.

Next the anterior bladder wall was scanned for blood flow for 5 minutes using 7.5 MHx probe, and the results classified as BF (+) and BF (-). The BF (+) cases were further classified into pulsatile and non-pulsatile flow groups. In the BF (+) cases maximum (Vmax) and minimum (Vmin) blood flow velocities were measured by pulse Doppler method [Figure - 2],[Figure - 3],[Figure - 4],[Figure - 5]. In the pulsatile flow cases, the resistive index (RI) was calculated (R.I = Vmax-Vmin/ Vmax), and the values expressed as mean ± SD.^[5]

Post-void rescanning was done to detect the amount of residual urine. All the cases were subjected to repeat UFM and CDU at 3 months and 6 months after surgical relief of IVO. RGU, MCU and cystourethroscopy were performed in the patients in whom UEBW remained elevated.

Results

All the patients were males with a mean age of 48.47±16.04 years. The mean duration of obstructive symptoms was 12.05 ± 7.20 months. BPH accounted for 42.11% of all the patients. PFR ranged from 2 to 18 ml/sec before surgery (mean 9.45 ± 4.10 ml/sec). After the relief of obstruction the mean PFR.increased to 17.56 ± 5.74 ml/sec (p<0.001) at 3 months. The mean post-void residual urine (PVR) was 69.75 ± 53.17 ml at presentation and decreased to a mean of 6.820 ± 12.04 (p<0.001) at 3 months after surgery. The bladder wall thickness decreased from a mean of 5.63 ± 2.59 mm at presentation to 3.33 ± 1.38 mm (p<0.001) at 3 months after surgery. However, in 18 patients (47.20%) it remained elevated at 3 months. After 6 months of operation bladder wall thickness remained elevated only in 5(13.16%) patients. At presentation UEBW ranged from 40.1 gms to 220.20 gms (mean 87.46 ± 37.01 gms), and significantly decreased to a mean of 43.99 ± 28.08 gms after 3 months of relief of obstruction in 29 (76.31%) patients (p<0.001). The corresponding mean UEBW in control group was 29.28 ± 4.27 gms (p<0.001). Normal cut-off value in our study was 40 gms, which is 5 gins more than the cut-off value in studies by Kojima et al and Pal DK.^[3],[4],[7] The substantially higher bladder weight in our study is probably due to delayed presentation of cases in our set-up. After 6 months, UEBW remained abnormally high in 5 cases and these cases on investigation revealed persistence of IVO.

At presentation blood flow in the anterior bladder wall was detected in 32 (84.21%) patients, while no flow was detected in 6 (15.79%) patients and 10 control cases. The mean R.I in BY (+) patients was 0.696 ± 0.08. After surgical relief of obstruction, blood flow was detected in 8 (21.05%) patients at 3 months and only in 5(13.10%) patients at 6 months [Table - 1]. Re-evaluation of these cases revealed re-stricture formation and re-stenosis of external meatus.

Discussion

The definitive pre-operative diagnosis of IVO will considerably help in formulating the treatment options and decrease the number of treatment failures significantly.^[3] In the past, bladder hypertrophy resulting from IVO was evaluated from endoscopic and radiographic findings, such as trabecular formation,^[8] but had the drawback of being invasive. Though AUA symptom index for BPH has high correlation with magnitude of urinary symptoms, but it lacks specificity. UFM though being a non-invasive tool has its shortcomings^{[9],[10],[11]} and cannot as a single test distinguish between IVO and impaired detrusor contractility. Although pressure flow study is the only method of knowing the presence or absence of IVO, invasive nature of the procedure limits its routine application.^[3] The recently proposed UEBW can quantitatively detect IVO with diagnostic accuracy of 86.2% and predict the reversibility of the bladder hypertrophic changes.^[4],[7] Batista et al^[12] evaluated the blood flow in human bladder by using laser Doppler flowmetry and concluded that laser Doppler can be utilized in measuring the blood flow changes in human bladder. Irwin and Gallowy, using laser Doppler in rabbits noted that weeks after reduction of outlet obstruction, blood flow decreased significantly. Dunn M^[1] reported a significant reduction in bladder wall blood flow in rabbits following decrease in intravesical pressure. Jermy et al^[15] concluded from a study in rabbits that partial outlet obstruction results in significant increase in blood flow which coincides with early cellular hyperplasia and hypertrophy.

In the present study, the UEBW reduced significantly and remained elevated only in 5 cases after 6 months of relief of obstruction. These cases on investigation revealed persistent obstruction. In l of these cases of meatal stenosis, the UEBW initially decreased from 84.6 gms to 40 gms at 3 months but increased again to 70.6 gms at 6 months because of restenosis. These findings suggest that the UEBW not only helps in diagnosis of IVO, but in follow-up as well. These observations are in concordance with observations of Kojima et al and Pal DK.^[3],[4]

The present study was designed on the assumption that blood perfusion in hypertrophied bladder wall increases and might decrease with the reduction of bladder weight. Bladder weight increases abnormally in patients with IVO as well as in neurogenic bladder. Naya Yashio^[5] used color Doppler flow imaging to differentiate these two groups. Blood flow was detected in 83.3% of obstructed group compared to 23.5% of neurogenic bladder group. In this study the IVO was detected with a diagnostic accuracy of 80.0%. The percentage of BF (+) and BF (-) cases was 84.21% and 15.79% respectively. In our study significantly correlation was found between the blood flow and UEB W [Table - 2]. Out of 32 BF (+) cases pulsatile flow was detected in 26 (81.25%) with a mean RI of 0.696 ± 0.08. Three months after relief of obstruction as the bladder weight decreased, blood flow pattern also changed, and 30 cases (79.95%) became BF (-). Three of the remaining 8 cases became BF (-) by six months. Thus a total of 5 (13.16%) cases remained BF (+) at 6 months and these cases also had persistently elevated bladder weight and bladder wall thickness. These findings are in conformity with our presumption that the blood perfusion and UEBW increases with IVO and returns to normal after relief of obstruction. Thus blood flow evaluation by CDU might represent histopathological as well as functional changes of the bladder detrusor and could help in evaluating the pathophysiology of bladder hypertrophy and follow-up of the cases after surgical relief of obstruction.

Conclusions

CDU is a simple, reliable, non-invasive and cost-effective investigation, which may replace pressure flow studies in future. The status of blood flow as evaluated by CDU might represent the histopathological as well as functional changes of bladder detrusor. Consequently, combination of UEBW and CDU could be a promising investigating tool in evaluating the prediction of the pathophysiology of bladder hypertrophy due to IVO.

References

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