Endometriosis is more common than previously thought among infertile women, affecting two-thirds of them seeking to get pregnant, a new study reports.
The study, “A two-third majority of infertile women exhibit endometriosis in pre-ART diagnostic hysteroscopy and laparoscopic chromopertubation: only one-third have a tubal obstruction,” was published in the journal Archives of Gynecology and Obstetrics.
Previous studies have reported that endometriosis causes infertility in up to 50% of women affected by the condition. Endometriosis makes it harder for women to get pregnant, with a monthly chance of conceiving naturally being reduced from 15%–20% (the monthly fecundity rate of healthy women) to 2%–10%.
The chance of conceiving is thought to be reduced by a number of factors including inflammation caused by endometriosis that affects egg development and its quality, and the egg-sperm interaction. Changes to the structure of the fallopian tubes and compromised contact with the ovary can also prevent conception. In addition, endometriosis and surgery to remove affected tissues can reduce the normal function of the ovarian tissue.
Assisted reproductive technology (ART) is the main treatment for women with endometriosis-associated infertility who want to get pregnant. However, having moderate or severe endometriosis is linked to reduced success of in vitro fertilization, the most effective form of ART.
Laparoscopy, a surgical procedure that allows doctors to visualize and remove endometrial tissue, increases the chances of pregnancy and live birth, particularly in women with mild and moderate forms of the condition.
In the study, researchers at Friedrich-Schiller-University, in Germany, set out to evaluate the prevalence (proportion of people with a given condition) of endometriosis in women among infertile couples who failed to conceive after trying for over a year. Their male partners were known to have normal sperm.
The study enrolled 300 women undergoing diagnostic hystero-laparoscopic chromopertubation — a combination of techniques that allows detailed visualization of the inner and outer parts of the uterus and fallopian tubes, as well as the surrounding pelvic organs and tissues — to look for obstructions and abnormalities.
Endometriosis was diagnosed in 201 (67%) of women in the study, a percentage that is higher than the 25% to 50% suggested by previous studies.
“The prevalence of endometriosis in infertile women from this study was higher than expected,” the researchers wrote.
Nearly 60% of the women diagnosed with endometriosis in the study had a minimal or mild form of the condition. Moderate endometriosis was seen in 16.9% of the women, and severe endometriosis in another 18.9%.
Women with endometriosis were more likely to have primary infertility — not being able to conceive for the first time after one year of regular intercourse without using birth control. In contrast, the majority of women without endometriosis had secondary infertility, that is, an inability to get pregnant after having conceived before (regardless of pregnancy outcome).
Data also showed that more women with endometriosis reported having pain with menstruation (dysmenorrhea), and shorter menstrual cycles. Endometriosis was also linked with a lower body mass index and blood levels of anti-Mullerian hormone, a measure of a woman’s reserve of eggs.
The most common locations of endometriosis were the sidewalls of the pelvis (53.2%), the uterosacral ligaments (flexible tissue connecting the uterine cervix to the tail bone; 41.8%), the posterior cul de sac (cavity between the back wall of the uterus and the rectum; 36.8%), and the bladder surface (32.2%).
Obstructed fallopian tubes were less common in women with endometriosis (34.32%) than in women without the condition (41.4%). Most women with an obstruction had moderate endometriosis, and the obstruction was usually found on the same side as the site of their endometriosis.
Overall, the data suggested that primary infertility, dysmenorrhea, and a shorter menstrual cycle “were independent risk factors for detection of endometriosis in diagnostic hystero-laparoscopy,” the researchers wrote.
Based on the results, the team concluded that the prevalence of endometriosis in infertile women was higher than expected, and suggested that with the use of “a minimally invasive examination technique such as laparoscopy, surgical infertility diagnostics can be performed quickly and safely.”
The researchers wrote that laparoscopy “should be made much more generous on the basis of these data,” noting that the technique can improve the “chances of pregnancy after surgical therapy of endometriosis.”