THE USE OF ULTRASOUND-ESTIMATED BLADDER WEIGHT IN DIAGNOSING BLADDER OUTLET OBSTRUCTION AND DETRUSOR OVER ACTIVITY IN MEN

Ultrasound estimated bladder weight in men attending the uroflowmetry clinic

AIMS

To determine if measurements of ultrasound estimated bladder weight (UEBW) provide an additional diagnostic tool when assessing men with lower urinary tract symptoms (LUTS) in the uroflowmetry clinic.

METHODS

One hundred men with LUTS attending the uroflowmetry clinic underwent transabdominal ultrasound measurement of bladder weight, using the BVM 9500 bladder scanner (Verathon Medical, Bothell, WA). These data were explored for any correlation between measurements of maximum flow rate (Q(max)) with UEBW, age, height, weight, body mass index (BMI), ICIQ M-LUTS score, M-LUTS voiding score, M-LUTS incontinence score, IPSS, IPSS quality of life score, voided volume, and post-void residual urine. Based on previously reported probabilities of bladder outlet obstruction (BOO), patients were grouped for analysis (Group 1 = Q(max) <10, Group 2 = Q(max) 10-15, Group 3 = Q(max) >15). A one-way ANOVA was undertaken to assess any difference in mean UEBW between the three groups.

RESULTS

Statistically significant negative correlations between Q(max) and age (r = -0.308, P = 0.002), M-LUTS voiding score (r = -0.298, P = 0.003), IPSS (r = -0.295, P = 0.003), and post-void residual (r = -0.213, P = 0.033) were observed. A statistically significant positive correlation between Q(max) and voided volume (r = 0.503, P < 0.01) was observed. No association between Q(max) and UEBW was observed (r = 0.12, P = 0.243). Mean UEBW for the three groups was remarkably similar. One-way ANOVA identified there was no statistically significant effect of UEBW on Q(max) F(2, 97) = 0.175, P = 0.840.

CONCLUSION

Mean UEBW did not differ significantly between the three Q(max) groups. Further work is required to investigate the relationship of Q(max) and UEBW in men with urodynamic confirmation of either BOO or detrusor underactivity.

Manual versus automatic bladder wall thickness measurements: a method comparison study

PURPOSE

To compare repeatability and agreement of conventional ultrasound bladder wall thickness (BWT) measurements with automatically obtained BWT measurements by the BVM 6500 device.

METHODS

Adult patients with lower urinary tract symptoms, urinary incontinence, or postvoid residual urine were urodynamically assessed. During two subsequent cystometry sessions the infusion pump was temporarily stopped at 150 and 250 ml bladder filling to measure BWT with conventional ultrasound and the BVM 6500 device. For each method and each bladder filling, repeatability and variation was assessed by the method of Bland and Altman.

RESULTS

Fifty unselected patients (30 men, 20 women) aged 21–86 years (median 62.5 years) were prospectively evaluated. Invalid BWT measurements were encountered in 2.1–14% of patients when using the BVM 6500 versus 0% with conventional ultrasound (significant only during the second measurement at 150 ml bladder filling). Mean difference in BWT values between the measurements of one technique was −0.1 to +0.01 mm. Measurement variation between replicate measurements was smaller for conventional ultrasound and the smallest for 250 ml bladder filling. Mean difference between the two techniques was 0.11–0.23 mm and did not differ significantly. The BVM 6500 device was not able to correctly measure BWTs above 4 mm.

CONCLUSIONS

Both BWT measurements are repeatable and agree with each other. However, conventional ultrasound measurements have a smaller measurement variance, can measure BWT in all patients, and BWTs above 4 mm.