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Long Beach, Calif. (Oct. 1, 2010) -- Conditions that cause chronic pelvic pain -- such as irritable bowel syndrome and overactive bladder -- often occur together, and now new research may have uncovered more information on why.
Nerves in the painful organ may ''leak'' information to nerves in an adjacent organ, and as a result the brain isn't sure which organ the pain message originates from, says Tirsit Asfaw, MD, a fellow in the department of obstetrics and gynecology at the University of Pennsylvania. She presented her findings this week at the annual meeting of the American Urogynecologic Society in Long Beach, Calif.
''Before, we couldn't explain why these were occurring together," Asfaw tells WebMD. For patients, the finding may be reassuring, she says, as they are now sometimes told after examinations and testing that nothing is wrong functionally in the adjacent organ in which they feel pain.
Chronic pelvic pain conditions are those in which pain has been ongoing, either continuously or intermittently, for six months or longer.
Patients with chronic pelvic pain often have symptoms from multiple organs, such as bladder and bowel, Asfaw says. Patients diagnosed with irritable bowel syndrome or IBS, for instance, often also have symptoms of bladder urgency, or overactive bladder, in which they get a sudden urge to urinate and may ''leak."
Previously, laboratory studies have found that when the colon is inflamed, the bladder muscle known as the detrusor is affected, with inflammatory markers found. The detrusor helps you empty your bladder by contracting, but when it contracts too much, it can lead to overactive bladder problems.
Asfaw's study took the previous research a step further by looking at an animal model to find out what happens to surrounding organs when the colon becomes inflamed and painful. "We induced colonic inflammation with a chemical," she says, and then tested bladder function.
"We saw a lot of bladder spasms in the animals with colonic inflammation," she says. "The contractions are similar to those in overactive bladder."
Those with the inflamed colons had five times the number of bladder contractions as the control animals.
What's happening? Asfaw believes that nerves from the inflamed organ, in this case the colon, may be communicating with nerves from the bladder, and a ''leakage of information" between nerves may occur.
When the messages reach the brain, "the brain doesn't know if the bladder or the colon is inflamed," she says. So it may send the pain message to both organs. "Pain is perceived as coming from the colon and the bladder," she says, because of this ''cross talk" between nerves, which scientists call ''cross-sensitization."
"Findings from this study support the mechanism that inflammation of one pelvic organ may lead to symptoms in an adjacent organ via cross-sensitization," Asfaw says.
''We know there's a lot of overlap" among pelvic pain conditions, says Rebecca Rogers, MD, professor of obstetrics and gynecology at the University of New Mexico Health Sciences Center, Albuquerque, who reviewed the study findings for WebMD.
Although the finding has no immediate applications, Rogers says that "this is a glimpse into the mechanism.This is a small first step in trying to define the origins of the overlapping problems."
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