Comparative Effectiveness of Two Models of Point-of-Care Ultrasound for Detection of Post-Void Residual Urine during Acute Ischemic Stroke: Preliminary Findings of Real-World Clinical Application

Abstract

We conducted a comparative study of two models of point-of-care ultrasound devices for measuring post-void residual urine (PVRU). We prospectively enrolled 55 stroke inpatients who underwent both real-time B-mode ultrasound (Device A) and automated three-dimensional (3D) scanning ultrasound (Device B), with a total of 108 measurements. The median PVRU volume of Device B was 40 mL larger than that of Device A. The PVRU difference between the devices was positively and linearly correlated with PVRU. The correlation of PVRU volume between the devices was strong, but the agreement level was only moderate. Measurement deviations were observed in 43 (40%) and 11 (10%) measurements with Device B and Device A, respectively. The PVRU volume was low in spherical bladder shapes but sequentially increased in triangular, undefined, ellipsoid, and cuboid bladder shapes. Further comparison of 60 sets of PVRU without measurement deviations revealed higher agreements between the devices at correction coefficients of 0.52, 0.66, and 0.81 for PVRU volumes of <100, 100-200, and >200 mL, respectively. The automated 3D scanning ultrasound is more convenient for learning and scanning, but it exhibits larger measurement deviations. Real-time B-mode ultrasound accurately visualizes the urinary bladder but tends to underestimate the urinary bladder when the PVRU volume is large. Hence, real-time B-mode ultrasound with automated PVRU-based adjustment of calculation formulas may be a better solution for estimating bladder volume.

Keywords: acute ischemic stroke; bladder ultrasound; point-of-care ultrasound; post-void residual urine.

Figure 1

Urinary bladder shapes identified with Device A with split-image mode (left: horizontal plane; right: vertical plane): (A) spherical shape, (B) triangular shape, (C) ellipsoid shape, (D) cuboid shape, and (E) undefined shape. The values of measured distance (green and yellow dashed lines on the horizontal plane and pink dashed line on the vertical plane) and automatically calculated volume are displayed on the lower left corner of each image.

Figure 2

Linear regression analysis of the difference between post-void residual urine (PVRU) volumes measured using Device A (left) and Device B (right).

Figure 3

(A) Spearman’s rank correlation coefficient analysis indicating a strong positive linear correlation between the post-void residual urine (PVRU) volumes measured using Devices A and B. (B,C) Intraclass correlation coefficient (ICC) and concordance correlation coefficient (CCC) revealing a moderate agreement between PVRU volumes measured using Devices A and B. CI, confidence interval.

Figure 4

(A) The large white arrows indicate a Type I measurement deviation in Device A for measuring bladder height (pink dotted line). The orange arrow indicates the correct distance of measurement. (B) The white arrowheads indicate a Type I measurement deviation in Device B for automatically tracking the contour of the bladder wall (green tracking line). The small white arrows indicate the correct outline of the bladder. (C) The large arrows indicate a Type II measurement deviation in Device B, in which a hypoechoic area (green tracking line) is mistaken for the bladder (the small arrows indicate the urinary bladder).

Figure 5

Questionnaire results of the nine ultrasound operators.