Contrary to popular opinion, the bladder does not shrink as we get older, research has found.
A more regular scene as we get older
Many people find they need to go to the toilet more frequently as they age.
But the University of Pittsburgh found little evidence this is due to a shrinking bladder - instead it may be down to an underlying condition.
Details of the study, of 95 women aged between 22 and 90, were presented to a conference of the American Urological Association in San Antonio.
Researcher Professor Neil Resnick said: "Many of us, after reaching a certain age, notice that we have to urinate more frequently and with more urgency.
"The standard assumption, that seems to have become part of our folklore, is that your bladder shrinks as you get older.
Urinating more than eight times in a 24 hour period
The immediate and strong urge to urinate
For some the inability to suppress urgency resulting in the leaking or loss of urine
"We found that this may not be the case."
The Pittsburgh team found that while bladder and urethral function deteriorate throughout adult life, bladder capacity rarely changes.
Women with normally aging bladders had weaker bladder sensation.
However, women who experienced increased bladder sensation as they aged actually had an underlying condition called detrusor overactivity (DO).
DO is a common condition, often referred to as overactive bladder, where the detrusor muscle that controls the emptying of the bladder contracts involuntarily, creating a strong, sometimes uncontrollable urge to empty the bladder.
Professor Resnick said: "Now, when a woman comes to her doctor and says that she thinks her bladder is shrinking, we realise that it is more likely she suffers from DO than from a smaller bladder.
"The good news is that DO is treatable, so that any woman experiencing urgency or incontinence should see her doctor."
Ian Holland, of the Continence Foundation, said DO was a common problem across all age ranges.
"There is a horrible preconception that incontinence is an old person's problem, but while it is true that it does become more common as people age, it also affects a significant number of younger people."