Residual urine volumes in patients with spinal cord injury: measurement with a portable ultrasound instrument

Spinal cord injured (SCI) patients are often placed on an intermittent catheterization (IC) program during their initial rehabilitation in an effort to establish a catheter-free state. A noninvasive method to quantitatively determine residual urine volumes would decrease unnecessary catheterizations and be useful in the management of an IC program. This study was undertaken to determine if bladder volumes could be accurately determined in a group of SCI patients using a portable ultrasound scanner. Fifteen SCI patients underwent a total of 224 ultrasonic bladder volume determinations and 57 urethral catheterizations. Immediately prior to catheterization, two investigators alternately performed a total of four ultrasound readings on each patient using a hand-held portable instrument, the BVI 2000. The first ultrasound volume determination was comparable to the average ultrasound volume (r2 = 0.956). For catheterized volumes versus the initial ultrasound volume determination, r2 = 0.80. The average error was 18% for catheterized volumes within the range 50-700ml. Our results compare favorably with both real-time scanning using standard equipment and other portable instruments. The noninvasive nature, negligible risks, and reasonable estimates of volume warrant consideration of portable ultrasound scanning for the determination of bladder volumes in SCI patients.