The Use of an Ultrasound Bladder Scanning Device in Women Undergoing Urogynaecologic Surgery

OBJECTIVE: To compare the accuracy of using a bladder scanner to measure post-voiding residual urine volume with measurement by intermittent catheterization in a postoperative urogynaecology population. METHODS: Prior to implementation of the study, nurses were trained in the use of a bladder ultrasound scanner. Post-void residual urine volume in postoperative patients was assessed by a nurse with the scanner; a second nurse, blinded to the scanner result, then catheterized the patient's bladder. Each patient rated the pain experienced with bladder scanning and with catheterization. A prospective comparison of the volumes assessed by ultrasound and measured by catheterization used 127 pairs of data; each woman served as her own control. The correlation of urine volumes was determined, and the difference in pain score was calculated using the Student t test. RESULTS: The mean age of patients was 56.5 years (range 40-79). All four bladder quadrants were visualized in 34.4% of scans. The correlation coefficient for volumes measured by scanning and catheterization was 0.70 (P < 0.001; range -349 mL to +692 mL). Consistently, using the scanner resulted in underestimation of the urine volume. The sensitivity of the bladder scanner (0.58 for residual volumes > 200 mL) therefore makes it a poor tool for assessing postoperative urinary retention in women undergoing urogynaecologic surgery. Pain scores recorded with catheterization (2.9/10) were significantly less than those recorded with bladder scanning (4.2/10) (P < 0.001). CONCLUSIONS: Bladder scanning by staff nurses had limited value in assessing postoperative residual urine volumes. The accuracy of assessment might increase with greater experience with the procedure. The greater discomfort reported by patients with use of the scanner supports continued use of catheterization to assess residual urine volume.