Pre- and post-void ultrasound is a non-invasive bladder scan done before and after urination to measure bladder volume and calculate post-void residual (PVR). It evaluates how completely the bladder empties, helping detect urinary retention, obstruction, dilation or diverticula, and guides management of incontinence or neurogenic bladder. The quick transabdominal scan informs need for further tests or treatment.

Worry if your pre-void bladder volume is consistently high (about 400–500 mL) or if you can’t pass urine and your lower abdomen is painful or visibly distended — this suggests urinary retention. Also be concerned if volumes are very low (<150 mL) but you have urgent, frequent voiding (overactive bladder). Seek urgent care for severe pain, fever, blood in urine, or reduced urine output.

Bladder pre- and post-void imaging evaluates how the bladder fills and empties, measures post-void residual urine, and detects incomplete emptying, obstruction (for example, prostatic enlargement or urethral strictures), diverticula, stones, or structural abnormalities. It helps diagnose urinary retention, incontinence, and recurrent infections, and guides treatment planning and follow-up by quantifying voiding function and identifying causes of lower urinary tract symptoms.

Normal pre-void urine volume in adults is typically about 300–400 mL. People may feel a first desire to void around 150–250 mL, a normal urge near 300 mL, and a strong urgent sensation around 350–500 mL; maximum bladder capacity is roughly 400–600 mL. Individual factors (age, fluid intake, medications, bladder conditions) can shift these values.

Treatment for post-void residual (PVR) urine depends on cause and severity. Options include bladder training, timed voiding, pelvic-floor exercises, and fluid management with habit changes; medications such as alpha‑blockers for benign prostatic obstruction; treating urinary infection if present; and reviewing drugs that cause retention. Significant or symptomatic PVR often requires clean intermittent catheterization or an indwelling catheter; refractory obstruction may need surgery or neuromodulation.

Pre-processing in ultrasound are signal and image adjustments applied before or during scan conversion—e.g., time‑gain compensation, beamforming, filtering, harmonic imaging and frequency compounding—to optimize echo capture and reduce noise. Post‑processing are image manipulations after scan conversion—gray‑scale mapping, edge enhancement, persistence, zoom, color mapping and measurements—to improve contrast, detail and diagnostic readability without altering raw data.