Aug. 20 (HealthDay News) -- A new test for endometriosis, the painful gynecologic condition that can impair fertility, requires no surgery and is extremely accurate, two studies show.
However, other experts said the accuracy of the new approach, which spots the telltale presence of nerve fibers, needs to be replicated, which the researchers also acknowledged.
Until now, a diagnosis of endometriosis -- in which the tissue that lines the uterus, called the endometrium, grows outside the uterus -- was made by inspection of the pelvis via laparoscopy, a procedure that requires anesthesia.
"Laparoscopy is invasive," said Dr. Thomas D'Hooghe, a professor of medicine at Leuven University in Belgium and co-author of one of the studies. "Our test is semi-invasive -- office-based, done by a gynecologist, limited discomfort."
Both studies were published online Aug. 19 in the journal Human Reproduction.
The condition affects about 5.5 million women and girls in the United States and Canada, according to the Endometriosis Association. The tissue that grows outside the uterus develops into growths or lesions that respond to the menstrual cycle in the way the uterine lining does, building and breaking down each month.
But the blood and tissue shed from these growths can't leave the body as menstrual blood does, so internal bleeding, pain, inflammation and infertility can result.
The cause is unknown, and the severity of the condition and the level of pain and other symptoms don't always correlate, experts said.
To do the new test, physicians take a small sample of the lining of the uterus by inserting the device used for taking an endometrial biopsy through the vagina. Then they test the sample for the presence of nerve fibers.
This enables them to determine whether or not endometriosis is present with nearly 100 percent accuracy, as D'Hooghe and his colleagues report. For the study, they compared samples of the endometrium from 40 women who had confirmed disease with samples from 20 women without the condition. The density of the small nerve fibers was about 14 times higher in the samples from patients with endometriosis than in those with a normal pelvis.
In a second study, researchers from Australia and Jordan took endometrial samples from 99 women presenting with pelvic pain or infertility, or both, who had undergone laparoscopy. They compared the laparoscopy and biopsy results. In 64 women who had endometriosis confirmed by laparoscopy, all but one tested positive for the presence of nerve fibers in the biopsy.
In the 35 women who did not have endometriosis diagnosed in the laparoscopy, no nerve fibers were found in 29 of the biopsies.
The new research builds on previous work, said study co-author Dr. Moamar Al-Jefout, an assistant professor of reproductive medicine at Mu'tah University in Karak, Jordan. That research, led by Dr. Ian Fraser in Australia, found that "women with endometriosis have nerve fibers in the functional layer of the endometrial, while women without endometriosis have no nerve fibers," Al-Jefout said.
Other experts lauded the results, but also had some caveats. "This test is [still] semi-invasive," said Mary Lou Ballweg, a spokeswoman for the Endometriosis Association. The biopsy procedure can be painful, she added.
Another expert, Dr. Pamela Stratton, chief of the gynecology consult service for the National Institutes of Health, who does endometriosis research, called the new studies "provocative."
"This is a very novel way of thinking about this," she said. "Everyone has been focusing on the lesions themselves."
Still, she said, more research is needed. "Its clinical usefulness isn't really known yet," she said of the new approach.
"Let's say the jury is out," agreed Dr. Karen J. Berkley, professor emerita of neuroscience at Florida State University in Tallahassee. "The underlying idea [linking nerve fibers and endometriosis] is not yet understood."
While the technique can be done in the office, it's not trivial, she said. "An endometrial biopsy can be a big deal for someone with a lot of pain," she said.
Even so, news of simpler tests "is very exciting," said Dr. David Healy, of Monash University in Melbourne, Australia, and president-elect of the International Federation of Fertility Societies. In a statement, he said: "If other doctors can confirm this test, this might become the standard way of diagnosing endometriosis. This would mean that the condition could be identified earlier, which could give real benefits for the infertile woman."
SOURCES: David Healy, M.D., Ph.D., president-elect, International Federation of Fertility Societies; Pamela Stratton, M.D., chief, gynecology consult service, National Institutes of Health, Bethesda, Md.; Karen J. Berkley, Ph.D., professor emerita, neuroscience, Florida State University, Tallahassee; Moamar Al-Jefout, M.D., Ph.D., assistant professor, reproductive medicine, Mu'tah University, Karak, Jordan; Thomas M. D'Hooghe, M.D., Ph.D., professor, medicine, Leuven Unviersity, Leuven, Belgium; Mary Lou Ballweg, spokeswoman, Endometriosis Association; Aug. 19, 2009, Human Reproduction, online