“The announcement…of a new simple test to diagnose endometriosis is very exciting,” Dr. David Healy, of Monash University, Melbourne, Australia, and president elect of the International Federation of Fertility Societies said in a statement.
“If other doctors can confirm this test, this might become the standard way of diagnosing endometriosis,” he said, adding that earlier diagnosis “could give real benefits for infertile women.”
The authors of the first report had shown in earlier work that small unmyelinated sensory nerve fibers are present in the functional layer of the endometrium in all women with endometriosis.
Now, in 99 women with pelvic pain and/or infertility undergoing diagnostic laparoscopy, the team assessed the efficacy of endometrial biopsy, using PGP9.5 immunostaining to identify the presence of nerve fibers.
In the 64 women who had endometriosis confirmed by laparoscopy, all but one had detectable nerve fibers on endometrial biopsy, the researchers report. In the 35 women found not to have endometriosis at laparoscopy, nerve fibers were present on endometrial biopsy in only six women.
The sensitivity and specificity of endometrial biopsy with nerve fiber detection for endometriosis was 98% and 83%, respectively, and the positive and negative predictive values were 91% and 96%, respectively, report Dr. Ian S. Fraser from University of Sydney and colleagues.
“Our results indicate that a negative endometrial biopsy result would miss endometriosis in only 4% of women,” they note. “Performing a planned laparoscopy only on a woman with a positive endometrial biopsy would result in endometriosis being confirmed in 80-90% of these women.”
The researchers point out that women in the current study were not receiving hormone treatment, as it has been observed that endometrial nerve fibers may no longer be detectable in the presence of hormonal therapy.
In another study yet to be published, Dr. Fraser’s team found no endometrial nerve fibers in women with adenomyosis, endometrial hyperplasia, chronic endometritis, leiomyomas or endometrial polyps, “which again emphasizes the unique presence of small C-nerve fibers in the functional layer in women with endometriosis,” they note.
In the second study, Dr. Thomas D’Hooghe, of the University of Leuven, Belgium and colleagues analyzed secretory phase endometrium samples from 20 women with laparoscopically and histologically confirmed minimal to mild endometriosis and from 20 control women with a normal pelvis.
They found that the density of small nerve fibers was roughly 14 times higher in endometrium from patients with endometriosis compared to controls (1.96 vs 0.14; p < 0.0001).
The combined analysis of neural markers PGP9.5, anti-vasoactive intestinal peptide and anti-substance P could predict the presence of minimal to mild endometriosis with 95% sensitivity, 100% specificity and 97.5% accuracy, Dr. D’Hooghe and colleagues report.
In an email to Reuters Health, Dr. Healy noted that it’s unclear at the moment which women would benefit most from biopsy for endometriosis. “Certainly infertile women would be group 1,” he noted, “and women with chronic pelvic pain would be group 2.”
After that? “Perhaps even when all women have a Pap test,” he said.
Biopsies for endometriosis might also be useful in low income countries that cannot afford safe laparoscopy, Dr. Healy noted.
Additional studies with the diagnostic test are “close to completion (about 1 year),” he added.
Human Reproduction 2009.