Urodynamics

Postvoid Residual Measurement

Postvoid Residual Measurement

This urodynamic test measures the amount of urine left in the bladder after urination. The remaining urine is called the postvoid residual. Postvoid residual can be measured with ultrasound equipment that uses harmless sound waves to create a picture of the bladder. Bladder ultrasounds are performed in a health care provider’s office, radiology center, or hospital by a specially trained technician and interpreted by a doctor, usually a radiologist. Anesthesia is not needed. Postvoid residual can also be measured using a catheter — a thin flexible tube. A health care provider inserts the catheter through the urethra up into the bladder to remove and measure the amount of remaining urine. A postvoid residual of 100 milliliters or more is a sign that the bladder is not emptying completely. Catheter measurements are performed in a health care provider’s office, clinic, or hospital with local anesthesia.