Endometriosis Study Yields Clue to Infertility
May explain why women with condition have trouble conceiving
THURSDAY, Oct. 17, 2002 (HealthDayNews) -- A laboratory study seems to give an important clue to the mystery of why so many women with the abnormality of the reproductive tract called endometriosis are infertile, British researchers report.
Endometriosis is a condition in which the tissue that normally lines the uterus grows abnormally in other parts of the pelvic cavity. It affects an estimated 5.5 million women in North America, and about 30 percent of them are infertile. Its most common symptom is heavy or unusual menstrual bleeding; women with the condition can also experience severe pain during menstruation or sexual intercourse and digestive system problems such as diarrhea or constipation. Its cause is unknown, and it is unclear whether it causes the infertility with which it is associated.
Now an exquisitely delicate study of the activity of cells lining the fallopian tube, which transports the egg toward sperm so that fertilization can occur, points to a cause-and-effect relationship, says a report in this week's issue of The Lancet. Cilia, the delicate hair-like projections that line the fallopian tube, act differently when exposed to fluid from women with endometriosis than from women without the condition, the report says.
"It is known that the ciliary beat and direction are very important for early implantation," says Dr. Ovrang Djahanbakhch, a professor of reproductive medicine at the London School of Medicine and leader of the research group. "We have shown that peritoneal fluid of women with endometriosis significantly reduces ciliary beat frequency."
That finding came from an experiment that compared ciliary activity of sections of fallopian tube from women who underwent a hysterectomy. Six of those segments were bathed in fluid from women with early-stage endometriosis, another six in fluid from women without the condition. The frequency of ciliary beating was reduced by about a quarter in the segments exposed to the fluid from the women with endometriosis, the researchers say.
"This is the first time that an objective study has shown something relevant relating endometriosis with infertility," Djahanbakhch says.
"Knowing how endometriosis causes the problem with infertility -- is it structural, chemical or a combination -- could be a big first step toward solving the problem," says Fay Campbell, executive director of the Endometriosis Association.
Djahanbakhch is looking for a chemical cause, some unusual molecule in the peritoneal fluid. "Some other studies in the past have shown a possible involvement of other substances," she says. "Now we are checking to see which are most relevant."
Somewhere down the road could be a fertility treatment, Djahanbakhch says: "If it is only one molecule, we can always develop antibodies to it and see if they prevent this inhibition."
However, a lot of work must be done before that goal can be achieved. One important next step is to see whether the same reduction of ciliary beat activity and of egg transport that has been seen in the laboratory occurs in women with endometriosis, and whether such a reduction is linked to infertility, and so years of research appear to lie ahead, Djahanbakhch says.
What To Do