Is ultrasound a reliable method for quantifying postvoid urine volume?

INTRODUCTION: In the treatment and follow-up of patients with Benign Prostatic Obstruction (BPO), uroflowmetry and evaluation of post voiding residual urine volume (PVR) are of great importance. Methods such as urethral catheter and suprapubic ultrasonography are generally used to measure PVR. In this study, we aimed to compare the accuracy of urethral catheter and suprapubic ultrasonography methods in detecting PVR.
METHODS: We included patients who underwent catheterisation for various clinical reasons. A total of 103 patients were included in the study. All patients were evaluated by suprapubic ultrasonography (USG) in the supine position to confirm that their bladders were empty. After 200 ml of saline was injected into the bladder with the help of a urethral catheter, the catheter was removed and the patients were instructed to urinate into a graduated cup.PVR was calculated by subtracting the volume voided by the patient from the volume injected into the bladder (200 ml).Abdominal USG was performed again within 5 minutes after voiding. Finally, the PVR values obtained were compared.
RESULTS: The accuracy of urethral catheter measurements was higher than suprapubic ultrasonography (p= 0.028). The sensitivity and specificity of suprapubic ultrasonography were found to be 100% (1.000 (0.904-1.000)) and 94% (0.940 (0.856-0.977)), respectively..

DISCUSSION AND CONCLUSION: Conclusions: USG demonstrating high specificity and sensitivity in assessing postvoid residual urine volume.