Pain is classified as chronic when it lasts or recurs for more than 3-6 months (“Classification of chronic pain” 2nd ed. Seattle: IASP Press, 1994). This universally accepted definition does not distinguish between physical and emotional pain. Categorically, pain is pain. Two prevalent chronic gynecologic diseases are closely related medically and emotionally. Forty percent to 50% of women with endometriosis have infertility; 30%-50% of women with infertility are found to have coexisting endometriosis. The approach to both is, typically, symptomatic treatment. In this month’s column, I examine the relationship between these ailments and how we can advise women on management.
Endometriosis is simply defined as the displacement of normal endometrial glands and stroma from their natural anatomical location to elsewhere in the body. With the recent identification of the disease in the spleen, endometriosis has been found in every organ system. Endometriosis is identified in 6%-10% of the general female population. The prevalence ranges from 2% to 11% among asymptomatic women and from 5% to 21% in women hospitalized for pelvic pain (Best Pract Res Clin Obstet Gynaecol. 2018;51:1-15). Compared with fertile women, infertile women are six to eight times more likely to have endometriosis (Fertil Steril. 2012;98:591-8).
Dr. Mark P. Trolice
Retrograde menstruation is the presumed theory for the origins of endometriosis, that is, the reflux of menstrual debris containing active endometrial cells through the fallopian tubes into the peritoneal cavity (Am J Obstet Gynecol. 1927;14:422-69). Because of the varied etiologies of the most common symptoms of endometriosis, dysmenorrhea, dyspareunia, dyschezia, and infertility, women visit, on average, seven physicians before being diagnosed (Fertil Steril. 2011;96:366). The delay in promptly identifying endometriosis is further impaired by the lack of specific biomarkers, awareness, and inadequate evaluation (N Engl J Med. 2020;382:1244-56).
The 2008 U.S. health care costs for endometriosis were approximately $4,000 per affected woman, analogous to the costs for other chronic conditions such as type 2 diabetes, Crohn’s disease, and rheumatoid arthritis (Hum Reprod. 2012;27:1292-9). The management of symptoms further increases the financial burden because of the effect of the disease on physical, mental, sexual, and social well-being, as well as productivity (Health Qual Life Outcomes. 2019;17:123).
We have known the paradoxical relationship between the stage of endometriosis and symptoms: Women with low-stage disease may present with severe pain and/or infertility but those with advanced-stage disease may be asymptomatic. Endometriotic cells and tissue elicit a localized immune and inflammatory response with the production of cytokines, chemokines, and prostaglandins. Given the usual intra-abdominal location and the small size of implants, endometriosis requires a surgical diagnosis, ideally with histopathology for confirmation. However, imaging – transvaginal ultrasound or MRI – has more than 90% sensitivity and specificity for identifying endometriomas (Cochrane Database Syst Rev. 2016;2[2]:CD009591).
The effect of endometriosis on fertility, particularly in women with minimal to mild stages, is not clear, and many studies have been retrospective. Tubal factor infertility can be a result of endometriosis. Per the 2020 Cochrane Database Systemic Reviews (2020 Oct;2020[10]:CD011031), “Compared to diagnostic laparoscopy only, it is uncertain whether laparoscopic surgery reduces overall pain associated with minimal to severe endometriosis; no data were reported on live birth. There is moderate-quality evidence that laparoscopic surgery increases viable intrauterine pregnancy rates confirmed by ultrasound compared to diagnostic laparoscopy only.” In women undergoing IVF, more advanced stages of endometriosis have reduced pregnancy outcomes as shown in recent meta-analyses (Obstet Gynecol. 2015;125:79-88).
The revised ASRM (rASRM) surgical staging classification of endometriosis has been widely used to describe the degree, although it poorly correlates with fertility potential (Fertil Steril. 2012;98:591-8). Women diagnosed with endometriosis may benefit from the Endometriosis Fertility Index (EFI), published in 2010 as a useful scoring system to predict postoperative non-IVF pregnancy rates (both by natural means and intrauterine insemination) based on patient characteristics, rASRM staging and “least function” score of the adnexa (Fertil Steril. 2010;94:1609-15).
Compared with diagnostic laparoscopy only, it is uncertain whether laparoscopic surgery reduces overall pain associated with minimal to severe endometriosis. “Further research is needed considering the management of different subtypes of endometriosis and comparing laparoscopic interventions with lifestyle and medical interventions (Cochrane Database Syst Rev. 2020 Oct;2020[10]:CD011031).”
The treatment of endometriosis is directly related to the desire for and timing of fertility since therapy is often contraceptive, as opposed to surgery. Because endometriosis is exacerbated by estradiol, the mainstay of medical therapy is initially combined hormonal or progestin-only contraception as a means of reducing pelvic pain by reducing estradiol production and action, respectively. GnRH-agonist suppression of follicle stimulation hormone and luteinizing hormone remains the standard for inactivating endogenous estradiol. In 2018, the U.S. Food and Drug Administration approved elagolix for the treatment of pain associated with endometriosis – the first pill specifically approved for endometriosis pain relief. An off-label approach for women is letrozole, the aromatase inhibitor, to reduce circulating estradiol levels. Unfortunately, estradiol suppression cannot be used solely long term without add-back therapy, because of the risk of bone loss and vasomotor symptoms.
Excision of endometriomas adversely affects ovarian follicular reserve (as indicated by lower levels of anti-müllerian hormone and reduced ovarian antral follicle counts on ultrasound). For women who want to preserve their fertility, the potential benefits of surgery should be weighed against these negative effects. Surgical treatment of endometriosis in women without other identifiable infertility factors may improve rates of spontaneous pregnancy. In women with moderate to severe endometriosis, intrauterine insemination with ovarian stimulation may be of value, particularly with preceding GnRH-agonist therapy (J Endometr Pelvic Pain Disord. 2018;10[3]:158-73).
Despite the reduction in IVF outcomes in women with moderate to severe endometriosis, it remains unclear whether surgery improves the likelihood of pregnancy with IVF as does the concurrent use of prolonged GnRH agonist during IVF stimulation. (Fertil Steril. 2012;98:591-8).