Endometriosis first diagnosed after menopause: A prospective analysis of the Nurses' Health Study II cohort

Most endometriosis research is limited to the premenopausal period; however, case series document endometriosis among postmenopausal women. Our objective was to quantify first diagnosis of endometriosis after menopause, including variation by age at menopause, mode of menopause (surgical or natural), and postmenopausal hormone use.

We analyzed data from the population-based Nurses' Health Study-II cohort 1989 baseline through 2019. Person-time of follow-up accrued from return of the first questionnaire with menopause report until confirmed death, laparoscopically-confirmed diagnosis of endometriosis after menopause, loss to follow-up or end of follow-up, whichever occurred first. We utilized multivariable Cox regression models to calculate risk of surgically-confirmed endometriosis after menopause by age at menopause, mode of menopause, and hormone use.

Among 80,148 women without a report of endometriosis diagnosed before menopause, 883 reported a first diagnosis of endometriosis after menopause. Median age at diagnosis of endometriosis after menopause was 50·6 years (after surgical menopause, 48.5 years; after natural menopause, 54·7 years). Mean time to endometriosis diagnosis was longer after surgical than after natural menopause (6·6 vs 5·7 years, median = 4.0 years). The majority of postmenopausal endometriosis diagnoses were among women with surgical menopause (69·9%), and those currently using hormones (69·5%). Compared with those with natural menopause but no hormone use (N = 110 cases), the risk of endometriosis was similar among women with natural menopause and hormone use (N = 137; HR = 1·16; CI = 0.89-1·49). In contrast, women with surgical menopause had a higher risk, both without hormone use (N = 78 cases; HR = 5·79; CI = 4.29-7·81) and, to a lesser degree, with hormone use (N = 477 cases; HR = 3·86; CI = 3·08-4.82).

A non-negligible 1·1% of women reported a first diagnosis of endometriosis after menopause. These diagnoses were predominantly among women with surgical menopause two or more years prior and likely represent a mixture of previously unrecognized persistent or recurrent premenopausal disease, and de novo postmenopausal lesions.