How should bladder wall thickness be measured? A comparison of vaginal, perineal and abdominal ultrasound.

Introduction: Measurement of bladder wall thickness using transvaginal ultrasound has previously been shown to discriminate between women with diagnosed detrusor overactivity and those with urodynamic stress incontinence. So far, no comparison has been made between abdominal, perineal and vaginal route for the measurement of bladder wall thickness. The aim of this prospective study was to determine if abdominal, perineal and vaginal ultrasound measurements of bladder wall thickness are comparable with each other.

Methods: 125 patients with lower urinary tract symptoms were asked to participate in the study. All patients had measurements at the trigone, the bladder dome and the anterior bladder wall. The order of either the abdominal, perineal or vaginal approach was computer-assisted randomly assigned. Ultrasound was performed using the Aloka SSD-1400 (Aloka® Co Ltd, Japan) with the vaginal 5 Mhz probe UST-984-5 and the abdominal and perineal probe was a 3.5Mhz curved array for SSd-1400. Ultrasound examination was made with the patient in supine position with a residual of less than 50ml.

Results: Means of bladder wall thickness are significantly different (p<0.05). Vaginal measurement of bladder wall thickness showed the smallest values for bladder wall thickness, abdominal the largest. At the trigone, differences were significant between vaginal and perineal ultrasound but not between abdominal and perineal approach.

Conclusion: Bladder wall thickness measurements do differ depending on the vaginal, perineal or abdominal approach.