Roses are red, the uterus is pink. If you had endometriosis, you would might need a drink.

The Sampson theory, which is most commonly accepted, suggests that the endothelial cells of the endometrium spill into the peritoneal cavity in ovulatory females. Once circulating in the peritoneum, they invaginate pelvic tissue. They proliferate and grow, causing lesions. Due to increased cell regeneration, the lesions could lead to cancer (Lebovic, et al., 1999). 

But only 10% to 15% of menstruating women experience endometriosis, so why is that? Ectopic, or abnormal, endometrial cells seem to escape immune system surveillance. In females without endometriosis, endometrial cells that have escaped beyond the uterus are detected by the NK cells of the immune system and undergo phagocytosis or apoptosis. Females with endometriosis have lower levels of NK cells (Lebovic et al., 1999). 

Additionally, ectopic endometrial cells express higher levels of ICAM-1 (intracellular adhesion molecule), which is a coreceptor for immune system cells. Once bound to the leukocyte, the ectopic endometrial cell does not undergo phagocytosis or apoptosis (Viganò et al., 1998).

What is the solution? The goal is to cause amenorrhea, or lack of a period. Most commonly, progestin (synthetic progesterone) will be prescribed to females to prevent menstruation and minimize the spillage of endometrial cells beyond the uterus. Estrogen causes bleeding, so combination birth control results in a light period. Therefore, it is recommended that progestin-only therapy is recommended to females with endometriosis. A GnRH (gonadotropin releasing hormone) antagonist may also be used to prevent the release of estrogen by the ovaries. On the other hand, surgical options work to remove the lesions, significantly reducing pain (Mechsner, 2022). 

In a time where exogenous hormones are viewed as "unnatural" and "bad," it's important that the way providers approach conversations with their patients about the prescription of hormonal contraception is tailored and meticulous. Oftentimes, providers prescribe whichever birth control to their female patient, leaving them in the blue when they experience symptoms. This is a turn off for hormonal therapy, and will be detrimental in the future when this hormone may be life-saving for our patient.  

References

Lebovic, DI., Mueller, MD., & Taylor, RN. (1999, September). Immunobiology of endometriosis. Fertility and Sterility. https://doi.org/10.1016/S0015-0282(00)01630-7. 

Mechsner S. (2022). Endometriosis, an Ongoing Pain—Step-by-Step Treatment. Journal of Clinical Medicine. https://doi.org/10.3390/jcm11020467

Viganò, P., Gaffuri, B., Somigliana, E., Busacca, M., Di Blasio, AM., & Vignali, M. (1998, December 4). Expression of intercellular adhesion molecule (ICAM)-1 mRNA and protein is enhanced in endometriosis versus endometrial stromal cells in culture. Mol Hum Reprod. doi: 10.1093/molehr/4.12.1150. PMID: 9872366.