Study of low bladder volume measurement using 3-dimensional ultrasound scanning device: improvement in measurement...

Using a Bladder Scan BVI6100 portable 3-dimensional ultrasound scanning device we examined measured values of bladder volume, especially focusing on volumes of 150 ml or less.

A total of 89 men and 71 women were enrolled in the study. We performed a comparison study between the measured value (the average of 3 bladder volume measurements after a trial in male and female modes) using the BVI6100 and the actual measured value determined by urethral catheterization in each patient. We examined factors that could increase the error rate and measuring techniques to decrease measurement errors. We also reviewed the training effects of measurement for a year.

Actual measured values in all patients correlated well with the average value of 3 measurements after a trial of BVI6100 in male mode. The correlation coefficient was 0.941 (0.967 after a year), the mean +/- SD error rate was -2.0% +/- 22.0% (-2.0% +/- 13.8% after a year) and the average variation coefficient was 12.4 (7.6 after a year). It was found that measurement results using the BVI6100 were influenced by patient factors, including extracted edges between the bladder wall and urine, thickened bladder wall, irregular bladder wall, flattened bladder, mistaking the prostate for the bladder in male mode, mistaking the bladder for the uterus in female mode, etc, and examiner factors, including changes in the angle between the BVI6100 and the abdominal wall, compatibility between the abdominal wall and the ultrasound probe, controlling deflection while using the probe, etc. It was also found that measurement accuracy could be improved regarding patient and examiner factors by choosing appropriate patients and performing concise measurement procedures (training effects).

When appropriate patients are chosen and proper measurement is performed, the BVI6100 provides significantly higher accuracy for determining lower bladder volume compared with existing abdominal ultrasound methods.