For transabdominal bladder volume evaluation, the probe is placed over the suprapubic area while the patient is in the prone position.Transvaginal ultrasound appears especially accurate for measuring low bladder volumes. It measures the bladder’s volume using the ultrasound machine's internal volume calculations or the mathematical equation seen below. The conventional ultrasound is used to visualize the bladder directly, either transabdominally or transvaginally. Ultrasound (conventional or real-time ultrasound) Measurement of post-void residual immediately after voiding is crucial for accurate measurement, with delays of as little as 10 minutes from bladder emptying to post-void residual measurement potentially causing clinically significant overestimation of post-void residual. Urinary catheterization is the gold standard for measuring the post-void residual. Post-void residual evaluation is by measuring the remaining urine in the bladder shortly after a voluntary void this can be accomplished through ultrasound, bladder scan, or by directly measuring the urine volume drained by a urinary catheter. See below for urinary catheterization technique. Urinary catheterization should be performed sterilely to prevent infection and to obtain an uncontaminated urine specimen. Urinary catheterization after voiding can provide both a post-void residual and a urine specimen. Specimen CollectionĪ urine specimen is not always indicated but can aid in the diagnostic evaluation, especially if there is a concern for infection as the etiology of the elevated residual volume. Evaluating for post-void residual is typically performed using ultrasound, a bladder scanner, or with a urinary catheter. A post-void residual volume helps in the evaluation of many disease processes, including but not limited to neurogenic bladder, cauda equina syndrome, urinary outlet obstruction, mechanical obstruction, medication-induced urinary retention, postoperative urinary retention, and urinary tract infections. Post-void residual volume (PVR) is the amount of urine retained in the bladder after a voluntary void and functions as a diagnostic tool.

Normal post void residual