Evaluation of a 3-dimensional ultrasound device for noninvasive measurement of urinary bladder volume in dogs
Matthew R. DiFazio, Justin D. Thomason, Natalia Cernicchiaro, David S. Biller, S Thomason, Paxton Harness
Abstract
BACKGROUND: The BladderScan Prime Plus (BPP; Verathon, Bothell, Washington) is an application-specific, three-dimensional ultrasound device used for human, point-of-care volumetry of the urinary bladder. OBJECTIVE: To estimate the BPP's accuracy, repeatability, and optimized settings for assessing urinary bladder volumes in dogs, a variable utilized in assessing micturition disorders. ANIMALS: Twenty-four, client-owned, healthy, male dogs presenting for routine examination. METHODS: Prospective examinations were conducted by an experienced ultrasonographer and a novice, selecting the BPP's "man" or "child" setting, and were compared to urine volume obtained by catheterization. RESULTS: Mean urine volume significantly varied by operator (P = .05), device setting (P < .001), and weight (P = .01); the "man" setting produced mean volumes nearer to catheterized volumes. The mean difference between BPP's "man" setting and catheterized volume was 0.88 mL, with maximal positive and negative disagreement of +23.2 mL to -55.3 mL (SD 19.0). Percent disagreement between BPP and catheterized volumes demonstrated a mean of -4.5%, with maximal positive and negative disagreement of +58.1% to -74.1% (SD 34.9). The experienced operator recorded volumes significantly (P = .05) higher than the novice, with difference in means of 3.2 mL. In dogs weighing >5.5 kg (n = 18/24), mean difference between BPP's "man" setting and catheterized measurements, regardless of operator, was not significant. CONCLUSIONS: Although small magnitude interuser variability is present in BPP examinations, the device provides accurate, though imprecise quantification of bladder volume in canids weighing >5.5 kg.