Year : 2000 | Volume
: 16 | Issue : 2 | Page : 118--121
Ultrasound estimated bladder weight: Its role to detect and follow-up of bladder outflow obstruction
Dilip Kumar Pal, Vijay Bora, RC Shukla, US Dwivedi, PB Singh
Departments of Urology & Radiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
Dilip Kumar Pal
«DQ»Ranikuthi«DQ», 28/1, Rudra Main Road, P.O. Bansberia, Dist. Hoogly, West Bengal - 712 502
Bladder weight was estimated by transabdominal ultrasonography in 40 patients with infravesical obstruction and in 10 control subjects without any infravesical obstruction. In obstructed group bladder weight was raised to 95.20 + 24.24 gms. compared to control group, where it was 35.44 + 4.27 gms. After three months of surgical relief of obstruction bladder weight came down to control range in 57.50% cases and after six months it reversed to normal weight (up to 40 gms) in 90% cases. In the remaining 10% cases where it remained greater than normal bladder weight persistent causes of obstruction were found. Ultrasound estimated bladder weight not only helps in diagnosis of infravesical obstruction but also helps to monitor the success of surgical treatment in bladder outflow obstruction.
|How to cite this article:|
Pal DK, Bora V, Shukla R C, Dwivedi U S, Singh P B. Ultrasound estimated bladder weight: Its role to detect and follow-up of bladder outflow obstruction.Indian J Urol 2000;16:118-121
|How to cite this URL:|
Pal DK, Bora V, Shukla R C, Dwivedi U S, Singh P B. Ultrasound estimated bladder weight: Its role to detect and follow-up of bladder outflow obstruction. Indian J Urol [serial online] 2000 [cited 2022 Jul 6 ];16:118-121
Available from: https://www.indianjurol.com/text.asp?2000/16/2/118/22209
It is well known that bladder outflow obstruction is followed by compensatory hypertrophy of bladder detrusor in man, , which can be measured quantitatively by transabdominal ultrasound as a non-invasive tool of investigation. ,,
Though nowadays pressure flow studies are recognised as the gold standard for the diagnosis of bladder outflow obstruction, their clinical use is limited due to invasive nature of the procedure  and limited availability, and ultrasound estimated bladder weight can predict bladder outflow obstruction quantitatively in a non-invasive way. ,,
So in view of an alternative simple technique of pressure flow studies in bladder outflow obstruction the present study was undertaken with an aim to standardise ultrasound estimated bladder weight as a routine quantitative test to assess the magnitude of bladder outflow obstruction and to monitor the therapeutic effects of bladder out flow obstruction in follow-up after surgical relief of obstruction.
Material and Methods
The present study was carried out in 40 patients with bladder outflow obstruction due to various causes and in 10 control subjects from July 1997 to June 1998 in the Department of Urology and Radiology of the Institute of Medical Sciences, Banaras Hindu University. 10 controls were randomly selected who presented with upper urinary tract disorders without any bladder outflow obstruction. Among 40 patients bladder outflow obstruction was due to benign hyperplasia of prostate, stricture urethra, bladder neck obstruction and meatal stenosis. All patients were subjected to urinalysis and urine culture. Only patients with sterile urine were taken in the study as UTI may cause increased bladder weight due to increased thickness of the bladder wall oedema. Confirmation of bladder outflow obstruction was done by uroflowmetry, retrograde urethrography or cystourethroscopy.
All the cases were scanned on a GE Logic 500 colour Doppler ultrasound equipment using a 7.5 MHz transducer probe. The method of bladder volume calculation was done as suggested by Kojima et al (1996),  assuming the full bladder as a spherical or ellipsoid shape. Then the bladder weight was obtained by multiplying the bladder volume by the specific gravity of the bladder tissue which is 1. 
After surgical relief of obstruction follow up bladder weight was estimated at three and six months. When the bladder weight remained elevated at six months uroflowmetry, urethrography or cystourethroscopy was done to detect the residual cause of obstruction, if any.
The present study was undertaken with adult patients between 16 and 74 years of age. No female or paediatric patients were included in this study. Mean duration of bladder outflow obstructive symptom was 10.74+5.74 months. In the control group the bladder wall thickness was 2-3 mm and ultrasound estimated bladder weight ranged between 32-40 gms with a mean weight 35.44+4.27 gms. In the obstructed group the ultrasound estimated bladder weight (UEB W) ranged from 64 to 180 gms with the mean weight of 95.20+24.24 gms [Table 1]. Initial peak flow rate, postvoid residual urine, bladder wall thickness was significantly improved after 3 months of surgical relief of obstruction and the difference was statistically significant [Table 2]. In 23 cases (57.50%) the bladder wall thickness reversed to normal (1-3 mm) but in 17 cases it remained elevated [Table 3] 3 months after surgical relief of obstruction. The UEBW came down to normal in 27 cases (67.50%) but in 13 cases (32.50%) it remained elevated [Table 4].
At six months follow-up 90% cases UEBW came down to normal range but in four cases (10%) it remained elevated [Table 5] though they had significantly reduced from their initial value. Those four cases were investigated for any residual bladder outflow obstruction. In all of them persistent causes of obstruction were found. 1 patient had residual prostatic adenoma with a UEBW of 74 gms. 1 patient developed stricture at bulbar urethra after TURP; his UEBW was 46 gms. 2 patients developed restenosis resulting in bladder outflow obstruction again at 6 months after O.I.U and had bladder weights of 64 gms and 74 gms.
It has been proved that following bladder outflow obstruction detrusor hypertrophy occurs and it is reversible following release of obstruction in rat model. , Similar findings have been observed in human subjects also.  Ultrasound estimated bladder weight is the only available parameter to detect detrusor hypertrophy and its reversible changes after relief of obstruction. ,,
UEBW in control subjects were 40 gms in our study and from 35 to 40 gms in other studies. , The mean UEBW in our study was 95.20±24.24 gms which was much higher in comparison to another study where it was 52.9±22.6 gms.  Increased weight in our study may be due to late presentation of cases in the Indian scenario. It is reversible in our study by 6 months after relief of obstruction if there is no residual obstruction.
Interestingly where the preoperative UEBW was more than 100 gms, it does not become eversible within 3months but takes 6 months [Table 6]. These findings suggest that UEBW not only helps in diagnosis of bladder outflow obstruction but also in follow up after surgery.
Since the introduction of ultrasound it has become a prominent diagnostic modality in the evaluation of urological diseases. Ultrasound estimated bladder weight is a reliable tool for predicting bladder outflow obstruction. It is also useful in monitoring therapeutic effects in man with urinary symptoms due to bladder outflow obstruction because of significant co-relation with the degree of obstruction. Considering its non-invasiveness and low cost of UEBW is promising as an auxiliary technique but further experiences are needed to determine whether it can replace pressure flow studies.
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