Ultrasound measurement of post-void residual

The measurement of the post-void residual (PVR) by ultrasound is a simple, quick and non-invasive test that quantifies the volume of urine remaining in the bladder immediately after voiding. It uses a portable ultrasound scanner or a dedicated device (bladder scanner) placed on the abdomen above the pubic bone. The post-void residual is a fundamental parameter in urology and neuro-urology. A significant residual (generally above 100 ml) may indicate bladder outlet obstruction, detrusor underactivity or a disorder of bladder-sphincter coordination. Its measurement is systematically combined with uroflowmetry. Suprapubic ultrasound not only measures the residual volume but also assesses bladder morphology (wall thickness, presence of diverticula, stones) and detects possible associated kidney abnormalities (pyelocaliceal dilatation). This dual anatomical and functional information makes it an essential first-line test. The measurement is generally performed using the ellipsoid volume formula (length × width × height × 0.52) or automatically by the bladder scanner. Its reliability is excellent and reproducible, making it an ideal monitoring tool for patients under regular urological surveillance.