Six out of every 10 cases related to endometriosis and adenomyosis are undiagnosed, particularly in menopausal women over the age of 50, researchers at the Clinical Epidemiology and Public Health Research Unit, in Italy, reported. The study, “Incidence and Estimated Prevalence of Endometriosis and Adenomyosis in Northeast Italy: A Data Linkage Study,” was published in PLOS ONE.

Endometriosis and adenomyosis are gynecological conditions identified by the presence of the lining of uterine tissue, called endometrial tissue, in areas where it should not be. Specifically, endometriosis is defined by the growth of the endometrial tissue outside the uterus, while adenomyosis is characterized by the presence of endometrial glands and stroma in the middle layer of the uterine wall, also called myometrium.

Both conditions are regulated by levels of the sex hormones estrogen and progesterone, and since estrogen levels drop after age 50, endometriosis and adenomyosis mainly pose problems before menopause. However, some reports suggest otherwise, noting cases of either condition in women beyond reproductive age.

Despite the serious complications these conditions might induce, such as infertility and chronic pelvic pain, reliable data on their incidence and prevalence is lacking. In industrialized countries, the mean time from onset of symptoms to diagnosis is estimated to be between five and 10 years. As a result, a specific Regional Register of Endometriosis in Italy was created to monitor the disease and set up appropriate strategies.

Researchers used the data link system to estimate incidence and prevalence rates of endometriosis and adenomyosis in women in the Friuli Venezia Giulia region of Italy from 2011 to 2013. Cases of newly diagnosed patients were taken from hospital discharge records, with diagnoses made by direct visualization for endometriosis and hysterectomy for adenomyosis. All cases with or without histological validation were considered, and diagnoses were treated as “new” if patients had not been diagnosed during the previous 10 years.

A total of 1,415 new cases, in women ages 15 to 83, of endometriosis and adenomyosis were identified from 2011–13 (1,017 and 398, respectively). Among this total, 979 (69%) cases were histologically confirmed (62% endometriosiss and 89% adenomyoses). In the age range of 15 to 50, a total of 1,116 new cases were identified, of which 719 had a positive histology (64%:59% of endometrioses and 85% of adenomyoses).

Overall, the incidence of endometriosis and adenomyosis in premenopausal women between age 15 and 50 was 0.14% and the prevalence calculated from the incidence of 2%. About 28% of diagnoses represent adenomyosis, which was found progressively prevalent after the age of 50 years.

“These result suggests that about 6 out of 10 cases were not identified before the active search of the disease. We believe that this might approximately be considered as the portion of relevant undiagnosed cases in the general population in this age range,” the authors wrote.

“The strength of the present study is indeed in the possibility of linking detailed health information anonymously, relative to inpatient records (diagnoses, interventions and demographics), with the opportunity of following subjects back in time. Details on the type of interventions and on the localization of the endometrial tissue allowed us to unambiguously distinguish between endometriosis and adenomyosis, and identify diagnoses based on direct visualization and positive histology ,” they concluded. “Our results show how the study of both endometriosis and adenomyosis should not be limited to women of premenopausal age. Further efforts are needed to sensitize women and health professional, and to find new data linkage possibilities to identify undiagnosed cases.”