Endometriosis and infertility: a cause-effect relationship?

Menstrual Blood Donation for Endometriosis Research: A Cross-Sectional Survey on Women's Willingness and Potential Barriers

An anonymous online survey in French was used to assess if endometriosis patients would be as ready as unaffected women to donate their menstrual blood for biological research on endometriosis and evaluate potential barriers to such donation. It was distributed in September 2022 by social media and two mailing lists, including a French patient organization. The questionnaire assessed participant age and brief medical history (hormonal contraception, endometriosis diagnosis, type of endometriosis), menstrual experience (menstrual blood abundance, dysmenorrhea), and whether participants would donate menstrual blood. Women who self-declared with an established endometriosis diagnosis versus no endometriosis were compared. Seven hundred seventy-eight women answered the survey. Among women with menstruation (n = 568), 78% are willing to donate menstrual blood for research. Importantly, this proportion was higher in women who declared having an established endometriosis diagnosis (83%, n = 299) compared to self-declared unaffected women (68%, n = 134, p < 0.001). The previous use of a menstrual cup and dysmenorrhea were significantly associated with the willingness to donate menstrual blood, while the use of hormonal contraception was significantly associated with an unwillingness to donate. Only the previous use of the menstrual cup had a predictive value for menstrual blood donation. No significant relationship was observed between menstrual blood donation and age, heavy menstrual bleeding and in endometriosis patients, endometriosis subtypes. In conclusion, women affected or not by endometriosis are largely willing to donate their menstrual blood for research on endometriosis, dysmenorrhea is not a barrier for donation, and women who use a menstrual cup are the more likely to donate.

Endometriosis and Risk of Adverse Pregnancy Outcomes

OBJECTIVE

To investigate the relationship between endometriosis and adverse pregnancy outcomes.

METHODS

Women between ages 25 and 42 years in 1989 (n=116,429) reported detailed information on pregnancies and reproductive health at baseline and every 2 years thereafter in the Nurses' Health Study II, a cohort study. In 2009, they completed a detailed, pregnancy-focused questionnaire. A total of 196,722 pregnancies were reported. Adverse pregnancy outcomes included spontaneous abortion, ectopic pregnancy, stillbirth, gestational diabetes mellitus (GDM), hypertensive disorders of pregnancy (preeclampsia or gestational hypertension), preterm birth, and low birth weight. We estimated the relative risks (RRs) and 95% CIs of adverse pregnancy outcomes comparing pregnancies in women with and without a history of laparoscopically confirmed endometriosis using multivariable log-binomial regression, with generalized estimating equations to account for multiple pregnancies per woman.

RESULTS

Endometriosis was associated with a greater risk of pregnancy loss (spontaneous abortion: RR 1.40, 95% CI 1.31-1.49; ectopic pregnancy: RR 1.46, 95% CI 1.19-1.80). Endometriosis was also associated with a greater risk of GDM (RR 1.35, 95% CI 1.11-1.63) and hypertensive disorders of pregnancy (RR 1.30, 95% CI 1.16-1.45).

CONCLUSIONS

We observed an association between laparoscopically confirmed endometriosis and several adverse pregnancy outcomes. Future research should focus on the potential biological pathways underlying these relationships to inform screening or preventive interventions.

A prospective cohort study of endometriosis and subsequent risk of infertility

STUDY QUESTION

Is there a temporal relationship between endometriosis and infertility?

SUMMARY ANSWER

Endometriosis is associated with a higher risk of subsequent infertility, but only among women age <35 years.

WHAT IS KNOWN ALREADY

Endometriosis is the most commonly observed gynecologic pathology among infertile women undergoing laparoscopic examination. Whether endometriosis is a cause of infertility or an incidental discovery during the infertility examination is unknown.

STUDY DESIGN, SIZE, DURATION

This study included data collected from 58 427 married premenopausal female nurses <40 years of age from 1989 to 2005, who are participants of the Nurses' Health Study II prospective cohort.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Our exposure was laparoscopically confirmed endometriosis. Multivariate Cox proportional hazards regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for infertility risk (defined as attempting to conceive for >12 months) among women with and without endometriosis.

MAIN RESULTS AND THE ROLE OF CHANCE

We identified 4612 incident cases of infertility due to any cause over 362 219 person-years of follow-up. Compared with women without a history of endometriosis, women with endometriosis had an age-adjusted 2-fold increased risk of incident infertility (HR = 2.12, 95% CI = 1.76-2.56) that attenuated slightly after accounting for parity. The relationship with endometriosis was only observed among women <35 years of age (multivariate HR <35 years = 1.77, 95% CI = 1.46-2.14; multivariate HR 35-39 years = 1.20, 95% CI = 0.94-1.53; P-interaction = 0.008). Risk of primary versus secondary infertility was similar subsequent to endometriosis diagnosis. Among women with primary infertility, 50% became parous after the endometriosis diagnosis, and among all women with endometriosis, 83% were parous by age 40 years.

LIMITATIONS, REASONS FOR CAUTION

We did not have information on participants' intentions to conceive, but by restricting the analytic population to married women we increased the likelihood that pregnancies were planned (and therefore infertility would be recognized). Women in our cohort with undiagnosed asymptomatic endometriosis will be misclassified as unexposed. However, the small proportion of these women are diluted among the >50 000 women accurately classified as endometriosis-free, minimizing the impact of exposure misclassification on the effect estimates.

WIDER IMPLICATIONS OF THE FINDINGS

This study supports a temporal association between endometriosis and infertility risk. Our prospective analysis indicates a possible detection bias in previous studies, with our findings suggesting that the infertility risk posed by endometriosis is about half the estimates observed in cross-sectional analyses.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by the National Institutes of Health (grant numbers: UM1 CA176726, HD52473, HD57210, T32DK007703, T32HD060454, K01DK103720). We have no competing interests to declare.

Role of the steroidogenic acute regulatory protein in health and disease

Steroid hormones are an important class of regulatory molecules that are synthesized in steroidogenic cells of the adrenal, ovary, testis, placenta, brain, and skin, and influence a spectrum of developmental and physiological processes. The steroidogenic acute regulatory protein (STAR) predominantly mediates the rate-limiting step in steroid biosynthesis, i.e., the transport of the substrate of all steroid hormones, cholesterol, from the outer to the inner mitochondrial membrane. At the inner membrane, cytochrome P450 cholesterol side chain cleavage enzyme cleaves the cholesterol side chain to form the first steroid, pregnenolone, which is converted by a series of enzymes to various steroid hormones in specific tissues. Both basic and clinical evidence have demonstrated the crucial involvement of the STAR protein in the regulation of steroid biosynthesis. Multiple levels of regulation impinge on STAR action. Recent findings demonstrate that hormone-sensitive lipase, through its action on the hydrolysis of cholesteryl esters, plays an important role in regulating STAR expression and steroidogenesis which involve the liver X receptor pathway. Activation of the latter influences macrophage cholesterol efflux that is a key process in the prevention of atherosclerotic cardiovascular disease. Appropriate regulation of steroid hormones is vital for proper functioning of many important biological activities, which are also paramount for geriatric populations to live longer and healthier. This review summarizes the current level of understanding on tissue-specific and hormone-induced regulation of STAR expression and steroidogenesis, and provides insights into a number of cholesterol and/or steroid coupled physiological and pathophysiological consequences.

A prospective study of insulin-like growth factor 1, its binding protein 3, and risk of endometriosis

Several retrospective case-control studies suggested that insulin-like growth factor 1 (IGF-1) or insulin-like growth factor binding protein 3 (IGFBP-3) was associated with endometriosis. However, results are inconsistent and no prospective study exists. We prospectively evaluated associations between plasma levels of IGF-1 and IGFBP-3 and laparoscopically confirmed endometriosis in a case-control study nested within the Nurses' Health Study II. Between blood collections in 1996-1999 and 2007, we ascertained 310 premenopausal women with incident endometriosis and 615 matched controls. We estimated incidence rate ratios and 95% confidence intervals using multivariable conditional logistic regression. We observed no statistically significant associations between endometriosis and IGF-1 (incidence rate ratio (IRR) = 0.88, 95% confidence interval (CI): 0.61, 1.27; Ptrend = 0.48), IGFBP-3 (IRR = 1.12, 95% CI: 0.80, 1.57; Ptrend = 0.51), and the IGF-1:IGFBP-3 molar ratio (IRR = 0.94, 95% CI: 0.66, 1.34; Ptrend = 0.64), comparing the top with the bottom tertile. IGF-1, IGFBP-3, and the molar ratio appeared to be positively associated with endometriosis risk among women aged <40 years at blood draw (IGF-1: IRR = 1.60, 95% CI: 0.86, 2.98; IGFBP-3: IRR = 1.85, 95% CI: 1.08, 3.16; IGF-1:IGFBP-3: IRR = 1.57, 95% CI: 0.85, 2.88) but not among women aged ≥40 years at blood draw (all Pheterogeneity ≤ 0.05). Overall, these data suggest that, if IGF-1 or IGFBP-3 plays a role in the etiology of endometriosis, it is minimal and perhaps only among younger women.

Obstetric Outcomes in Patients Treated for Deep Pelvic Endometriosis

Purpose

The aim of this study was to assess obstetric outcomes and symptoms during and after pregnancy in women submitted to surgical treatment for deep pelvic endometriosis.

Methods

We evaluated 123 women who underwent surgery for severe deep pelvic endometriosis-related symptoms. Interventions were excision of rectovaginal septum nodule with or without rectal or vaginal resection, or excision of nodule of uterosacral ligaments. On the basis of pregnancy desire, patients were submitted to a telephone interview and asked if there had been a pregnancy and its outcome. They were also asked to describe their pain symptoms before, after and during the pregnancy.

Results

From the 123 patients, we selected 43 women desiring pregnancy after surgery, who answered the telephone interview. Twenty-four patients (55.8%) got pregnant. We recorded 34 pregnancies a mean 21.8 ± 17.9 months after surgery. In the group of 25 full-term pregnancies, 14 women (56%) had a vaginal delivery without complications, and 11 (44%) underwent a cesarean section. In only 3 cases, was the indication of cesarean section related to previous surgery. Seventy-one percent of women treated without rectal or vaginal resection delivered vaginally. We also registered 1 case of uncomplicated vaginal delivery in a patient with vaginal resection and another 1 in a patient with rectal resection. In the patients who complained of pain before pregnancy, we observed a resolution of pain symptoms during pregnancy, but after delivery these symptoms reappeared.

Conclusions

In patients submitted to surgery for deep pelvic endometriosis, even in cases of vaginal or rectal resection, a cesarean section is not always mandatory.

Fertility and clinical outcome after bowel resection in infertile women with endometriosis

Bowel resection for endometriosis improves pain symptoms and quality of life in symptomatic women. However, little is known about fertility after surgery, particularly after such treatment in women suffering from infertility. The aim of the present study was to evaluate post-operative fertility and long-term clinical outcome after laparoscopic colorectal resection for endometriosis in infertile women. This study reports clinical outcomes in 62 infertile women who underwent laparoscopic excision of endometriosis with segmental bowel resection performed for severe intestinal symptoms. Among women younger than 30 years trying to conceive spontaneously, the cumulative pregnancy rate was 58% and the cumulative pregnancy rate was 45% in those aged 30-34 years. The total pain recurrence was 9.7% (six cases) and endometriosis recurrence was diagnosed by ultrasound in 14.5% (nine cases) during the follow-up period. Four of these patients needed further surgery because of severe symptoms. The surgical treatment of bowel endometriosis seems to improve pain symptoms and patients' satisfaction rates, and it could also be indicated in infertile women.

Effects of surgical induction of endometriosis on response properties of preoptic area neurons in rats

Subfertility and severe pelvic pains are symptoms associated with endometriosis (ENDO), a common condition among women that is characterized by the growth of the uterine endometrium on the surface of organs within the pelvic region and abdominal cavity. The contribution of the CNS to symptoms associated with ENDO is not known. In the present study, the preoptic area (POA) of the hypothalamus was investigated, as this region of the forebrain is known to play an important role in the neuroendocrine control of the reproductive cycle, mating behavior, and antinociception. Female rats were either induced for ENDO by autotransplantation of uterine tissue (n=20) or uterine fat for surgical sham controls (n=11). Terminal extracellular electrophysiological recordings (urethane anesthesia) were conducted in the POA six weeks post-ENDO induction when the rats were in either the proestrus or metestrus stages of their estrous cycle. Significant differences were found between the ENDO versus SHAM groups of animals for the proportion of inhibitory responses as well as the percentage of neurons responding to stimulation of the abdominal branches of the vagus, which innervates portions of the female reproductive tract, including the ovaries. The endometriotic cysts were found to be significantly larger in proestrus rats (stage when hormones are elevated). These data demonstrate that the responses of POA neurons are influenced by the presence of endometriotic cysts in the abdominal cavity. Since the POA is known to be part of the neural circuitries that mediate nociception and fertility, any deviation from its normal activity under ENDO conditions could contribute to the constellation of symptoms that ensue.

Endometriosis and Chronic Pelvic Pain: Unraveling the Mystery Behind this Complex Condition

Nurses often encounter patients with chronic pelvic pain associated with endometriosis, which is a puzzling and problematic gynecologic condition that has continued to plague women and baffle doctors and researchers worldwide since it was first identified by Dr. J. Sampson in the 1920s (Sampson, 1940 ). Endometriosis is defined as the growth, adhesion and progression of endometrial glands and stroma outside of the uterine cavity, with cellular activity evident in lesions, nodules, cysts or endometriomas (Audebert et al., 1992 ). Although it typically appears benign on histopathology, endometriosis has been likened to a malignant tumor since the lesions grow, infiltrate and adhere to adjacent tissues and interfere with physiologic processes (Kitawaki et al., 2002 ; Noble, Simpson, Johns, & Bulun, 1996 ). Ectopic endometriotic growths respond to cyclic changes of estrogen and proliferate and shed in a manner similar to eutopic endometrium. This cyclic ectopic activity results in internal bleeding, formation of scar tissue, inflammation and sometimes debilitating chronic pain (Kitawaki et al.).

Evaluation of monocyte chemotactic protein-1 levels in peripheral blood of infertile women with endometriosis

OBJECTIVE

To test whether serum monocyte chemotactic protein-1 (MCP-1) chemokine levels correlate with endometriosis in infertile women.

STUDY DESIGN

A group of women with endometriosis (n = 18, infertile) was compared with patients with uterine leiomyoma (n = 16, fertile), unexplained infertility (n = 5, infertile), and healthy women (n = 16, fertile). MCP-1 expression levels were evaluated by ELISA assay. The data obtained were statistically analyzed using the Mann-Whitney test. P-Values <0.05 were considered as significant.

RESULTS

MCP-1 concentrations (median; range of values) in serum were as follows: women with endometriosis (221; 101-635 pg/ml), women with unexplained infertility (167, 114-234 pg/ml), women with uterine leiomyoma (137; 88-200 pg/ml), and healthy donors (123; 98-194 pg/ml). Significant differences were observed in the women with endometriosis compared with those with uterine leiomyoma (p = 0.02) and healthy donors (p = 0.002). Among the women with endometriosis, the level of significance in MCP-1 level at rAFS stages III-IV was higher than that at rAFS stages I-II compared with healthy donors and women with leiomyoma (p = 0.002 and p = 0.02, respectively).

CONCLUSIONS

These data show that an increased level of MCP-1 can characterize infertile women with endometriosis. However, further studies are needed to be able to determine whether increased MCP-1 chemokine expression can be related to infertility or is a result of endometriosis progress.

Fertility after laparoscopic colorectal resection for endometriosis: preliminary results

OBJECTIVE

To examine fertility, reproductive outcomes, and determinants of fertility after laparoscopic segmental colorectal resection for endometriosis.

DESIGN

Retrospective longitudinal study.

SETTING

Tertiary university gynecology unit.

PATIENT(S)

The study population consisted of 34 women with colorectal endometriosis, of whom 22 wished to conceive. Demographic, surgical, and histological characteristics of 10 women who conceived were compared with those of 12 women who failed to conceive.

INTERVENTION(S)

Laparoscopic colorectal resection for endometriosis.

MAIN OUTCOME MEASURE(S)

Rates of pregnancy and live birth.

RESULT(S)

Mean follow-up after segmental colorectal resection was 24 months (range 6-42 months), and the pregnancy rate was 45.5%. The median time to conceive was 8 months (range 3-13 months). Twelve pregnancies occurred in 10 women, comprising nine spontaneous singleton pregnancies (7 vaginal deliveries, 1 cesarean section, and 1 ongoing pregnancy), and three pregnancies obtained by IVF (one miscarriage, one ongoing twin pregnancy, and one triplet pregnancy necessitating cesarean section at 29 weeks for premature rupture of the membranes, with two surviving infants). The live birth rate was 82%. The women who did and did not conceive did not differ in terms of mean follow-up, mean age, body mass index (BMI), parity, smoking, use and duration of oral contraception (OC), duration of infertility, or the length of the resected colorectal segment. Uterine adenomyosis was the main determinant of pregnancy after colorectal resection.

CONCLUSION(S)

These preliminary results suggest that extensive laparoscopic segmental colorectal resection for endometriosis can enhance fertility, with high rates of spontaneous pregnancy and live birth.

Future directions in endometriosis research

Future research in endometriosis must focus on pathogenesis studies in the baboon model, the early interactions between endometrial and peritoneal cells in the pelvic cavity at the time of menstruation, and potential differences between eutopic endometrium and myometrium in women with and without endometriosis. More integration is needed between the areas of epidemiology and genetics. Pelvic inflammation in women with endometriosis could be the target for new diagnostic and therapeutic approaches. Important questions remain regarding the relationship between endometriosis and environmental factors. Systemic and extrapelvic manifestations of endometriosis must be analyzed carefully, and better tools are needed to measure quality of life in women with chronic pain caused by endometriosis. Most current evidence supports a causal relationship between endometriosis and subfertility, and the spontaneous progressive nature of endometriosis has been demonstrated in 30% to 60% of patients. Recurrence of endometriosis after classic medical and surgical therapy is a major and underestimated problem, especially in women with advanced disease. Integrated clinical and research teams are needed that combine expert medical, surgical, and holistic care with state-of-the-art research expertise in immunology, endocrinology, and genetics to discover new diagnostic methods and medical treatments for endometriosis.

Surgical management of endometriosis-associated pain

General surgical guidelines are reasonable, but treatment frequently must be individualized. Laparoscopic coagulation can be used for many cases of superficial endometriosis. Resection seems to be associated with an increased resolution of endometriosis. Resection increases the difficulty of the procedure, the time of the operation, and the cost, however. When endometriosis is found coincidentally, it may need no treatment because many women have endometriosis as a self-limited disease. Distinguishing patients who need no treatment from patients who need intermediate or extensive treatment can be difficult. Care is needed to attempt to ensure that patients are neither overtreated nor undertreated.