What is the role of a bladder scan?

• A. To estimate post-void residual volume and assess urinary retention noninvasively
• B. To measure blood pressure
• C. To diagnose epilepsy
• D. To visualize the bladder with radiation

Answer: (A)

A bladder scan uses ultrasound to estimate how much urine remains in the bladder after a person voids, which is the post-void residual. This measurement helps determine whether the bladder emptied properly and whether urinary retention is present. The test is quick, noninvasive, and performed at the bedside, avoiding radiation and the need for catheterization just to measure the residual. If the residual is small, emptying is likely adequate; a high residual suggests retention and indicates further evaluation or management, such as addressing a blockage or improving bladder contractility. The other options don’t fit because a bladder scan isn’t about measuring blood pressure, diagnosing epilepsy, or using radiation to visualize the bladder; those tasks involve different tests and imaging methods.