Pre- and post-void ultrasound are noninvasive bladder scans done before and after urination to measure bladder volume and calculate post-void residual (PVR). They assess how completely the bladder empties, help diagnose urinary retention, incontinence, recurrent infections, and evaluate treatment. The exam is quick, painless, uses an ultrasound bladder scanner or sonography, and guides management by quantifying retained urine.

You should worry about pre-void volume if it’s consistently too low (<150 mL) or excessively high (>500 mL): low volumes may reflect overactive bladder or invalidate uroflow tests, while high volumes suggest poor emptying or retention. Seek prompt care for inability to pass urine, severe pain, fever, or blood in the urine. See your GP or a urologist if abnormal readings or bothersome symptoms persist.

An ultrasound before and after urination measures bladder volume pre-void and post-void to calculate the post-void residual (PVR). It’s a quick, noninvasive scan using sound waves to assess how completely the bladder empties, detect retention, obstruction or neurogenic bladder, and guide treatment. Normal PVR is usually low; elevated residuals suggest incomplete emptying and need further evaluation.

Pre and post void bladder imaging is performed to evaluate bladder anatomy and function, identifying stones, tumors, wall thickening, diverticula or reflux, and to measure post-void residual urine. Comparing full and emptied states detects incomplete emptying, outlet obstruction or neurogenic bladder, guides diagnosis (for example retention or reflux), and helps plan treatment or surgery by quantifying urinary retention and emptying efficiency.

Pre-processing in ultrasound are adjustments applied to raw echo signals before image storage/display—beamforming, time‑gain compensation, filtering, frequency compounding and log compression—that shape image quality and cannot be reversed later. Post-processing includes manipulations on stored or displayed images—gray‑scale mapping, edge enhancement, persistence, zoom, color mapping and measurements—that modify the presented image without altering the original acquired raw data and are often reversible.

Treatment depends on the cause. For post‑void dribbling: pelvic floor exercises (Kegels), timed/double voiding, penile compression in men, and topical vaginal estrogen for postmenopausal women. For significant post‑void residuals: treat infections, relieve obstruction (alpha‑blockers or surgery for BPH), or use clean intermittent catheterization. Lifestyle changes (fluid/caffeine control, weight loss) and bladder training help. Measure residual volume by ultrasound first.