Urology & Urogynecology > Education and Reference

Capacity measurements applicable to urodynamics include:

• Functional Bladder Capacity – requires the completion of a 24-hour voiding diary prior to testing. Functional capacity is the largest single volume voided during a given 24 hour period.
• Maximum Cystometric Capacity – The volume at which a patient, with normal sensation, feels that he/she can no longer delay micturition (strong desire).

WHAT IS THE MAXIMUM AMOUNT OF VOLUME THAT SHOULD BE INSTILLED IN A PATIENT’S BLADDER DURING A CMG?

Stability during storage and contractility during emptying are dependent upon:

• The general health and condition of the smooth muscle lining of the bladder
• A balanced system of chemicals and receptors
• An intact neurosensory pathway to the bladder

A normally functioning detrusor demonstrates no involuntary phasic contractions, despite provocation.

Detrusor overactivity is a urodynamic observation characterized by involuntary detrusor contractions during the filling phase, either spontaneous or provoked.

First desire to void is the feeling, during filling cystometry, that would lead the patient to pass urine at the next convenient moment; but voiding can be delayed if necessary.

Strong desire to void is the persistent desire to void without fear of leakage.

Other Sensations:

• Urgency - a sudden, compelling desire to void
• Increased bladder sensation
• Reduced bladder sensation
• Absent bladder sensation
• Non-specific bladder sensations
• Bladder pain