There are many external factors that we suspect may play a role in the growth and development of endometriotic lesions. The main contenders being environmental toxicants such as dioxin or bisphenols which are thought to disrupt the body’s normal hormonal balance. Other factors that have been suggested include metals like lead and cadmium, eating red meat or trans fats and alcohol consumption. However, a recent study has identified another potential candidate, semen.
Yes that’s right, a study from Japan has found that seminal fluid increases the growth of endometriotic cells in culture. The logic behind the original thinking is that seminal fluid contains a lot of macromolecules, a rather nonspecific term that in this context refers to factors which may lead to the growth of endometrial tissue. This study found that when seminal fluid plasma was added to endometrial cells from women with and without endometriosis it stimulated growth of these cells. What is interesting is the finding that normal endometrium from women with endometriosis displayed increased growth over normal endometrium from women without endometriosis. This suggests that even the normal endometrium from women with endometriosis is somehow more sensitive to growth signals. This lends some support to the retrograde menstruation theory. If endometrial cells are somehow ‘primed’ for increased growth capacity in some women, then when these cells are refluxed they will be more likely to implant, proliferate and eventually form endometriotic lesions.
The growth signals in question that are found in seminal fluid are hepatocyte growth factor (HGF), estrogen and prostaglandin E2 (PGE2). PGE2 in particular has been touted as a major factor regulating a number of processes essential for developing and sustaining endometriosis.
Now you may very well ask, as I did “how does seminal fluid come into contact with endometriotic lesions?” After all endometriotic lesions are found on the outside of the pelvic organs. Apparently seminal fluid can come into contact with endometriotic lesions via “hematogenous dissemination or direct tissue perfusion through the anterior or posterior vaginal formix after sexual intercourse” which basically means it can diffuse through the rear wall of the vagina much like water diffusing through a sponge. I need to point out though that this does not suggest endometriosis can be caused by unprotected sex, but it may irritate the existing endometriosis.
However, on the other side the macromolecules found in seminal fluid promotes the development and implantation of the embryo, which is good if you are trying to conceive. Of course, as with any new findings there is more work to be done before we draw any definitive conclusions, further studies may prove or dispose what has been found.