Endometriosis is a condition where the uterine lining (endometrium) is found outside the uterus. It is a common, chronic disease that typically presents with pelvic pain, infertility or an ovarian cyst.
Classical studies suggested that 25% to 50% of infertile women have endometriosis and that 30% to 50% of women with endometriosis are infertile. Infertile women are 6 to 8 times more likely to have endometriosis than fertile women. Among women with pelvic pain, 30 to 80% will have endometriosis.
There is a definite association between endometriosis and infertility. However, it is not clearly established that endometriosis always causes infertility. Most specialists will agree that there is a causal relationship between the two in patients with severe endometriosis who have significant amounts of scar tissue or whose pelvic organs are distorted by growths or cysts. In these patients, surgery will improve the chances of pregnancy.
What Are the Links Between Endometriosis and Infertility?
Several relationships between endometriosis and infertility have been proposed:
Distorted pelvic anatomy: When endometriosis causes scar tissue, this can interfere with the ability of the ovary to release eggs. Scar tissue also can prevent the tube from picking up the egg and transporting it.
Altered peritoneal function: Endometriosis induces inflammatory changes in the thin membrane lining the pelvis and abdominal cavity (peritoneum). This results in the release of substances (prostaglandins, proteases, cytokines, VEGF). These in turn mat have a negative impact on egg, sperm, embryo, or fallopian tube function.
Altered hormonal and cell-mediated function in the uterine lining: These abnormalities may alter the ability of the uterine lining to receive an embryo.
Hormonal and ovulatory abnormalities: Endometriosis patients may have hormonal imbalances that interfere with ovulation (luteinized unruptured follicle syndrome, luteal phase defect,abnormal follicular growth, premature as well as multiple LH surges).
Impaired implantation: Endometriosis negatively impacts cell adhesion molecules (αvβ3 integrin) and other substances (L-selectin) that are necessary for the embryo to implant in the uterus.
Oocyte and embryo quality: In vitro fertilization studies have shown that patients with endometriosis can have poor quality eggs and embryos. Embryos derived from women with endometriosis appear to develop more slowly compared to those embryos derived from women with tubal disease.
Abnormal uterotubal transport: The fallopian tube may be functionally compromised in patients with endometriosis. Studies using a special technique (hysterosalpingoscintigraphy, HSSG) have shown that even when the tubes are patent; their ability to transport gametes (eggs, sperm, embryos) is compromised.
Dr. Karande is Board Certified in the specialty of Obstetrics and Gynecology as well as the subspecialty of Reproductive Endocrinology and Infertility. He is a Fellow of the American College of Obstetricians and Gynecologists and Member of the American Society for Reproductive Medicine.