"3-D Ultrasound Device
Rapid Determination of Bladder Volume"
From the September, 1997 issue of Urology (Volume 50, No. 3)
Leonard S. Marks, Frederick J. Dorey, Maria Luz Macairan, Cindy Park, and Jean B. deKernion (USRF and UCLA Urology Department)
Objectives. We sought to assess accuracy, reliability, and clinical utility in the non-invasive determination of bladder volume, using an automated, compact 3-D ultrasound device.
Methods. 249 adult outpatients were prospectively tested for accuracy (n=182), by comparing scan vs. catheter volumes, or reliability (n=67), by comparing the scan readings of two independent observers. Two models of the bladder scan device were tested (BVI-2500, 1994 and 1995 models).
Results. Scan and catheter volumes were correlated (y=1.02x + 12.6, R2=0.90, p<0.001) across a range of zero to 1015 cc, regardless of which machine model was used. Scan volume underestimated catheter volume by an average of 10 cc in males and 20 cc in females. If a scan-predicted volume > 100 cc were used as a cut-point for clinical importance, then the device exhibited a sensitivity of 97%, a specificity of 91%, and an overall accuracy of 94%. These results were not affected by age, gender, height, weight, diagnosis, uterine presence/prostate size, or user experience. The two observers, one a graduate physician and the other a college student, achieved essentially the same volume determinations (y=0.96x + 0.13, R2=0.90, p<0.001).
Conclusions. Volume determinations obtained with the bladder scan device are accurate and reliable in adult outpatients. A special technician is not required. These results may be attributable to use of automated planimetry and 3-D volumetry, rather than a fixed geometric formula, to custom-measure each bladder shape.