How common is adenomyosis? A prospective study of prevalence using transvaginal ultrasound in a gynaecology clinic

STUDY QUESTION: What is the prevalence of adenomyosis in a population of women attending a general gynaecological clinic? SUMMARY ANSWER: Adenomyosis was present in 206 of 985 [20.9; 95 confidence interval (CI): 18.523.6] women included in the study. WHAT IS KNOWN ALREADY: Previous studies of occurrence of adenomyosis have been limited to women who underwent hysterectomy, which is likely to overestimate its prevalence compared with the general population of women. There are no large prospective studies on the prevalence of adenomyosis, either in the general population of women or in a general gynaecology clinic setting. STUDY DESIGN, SIZE, DURATION: This was a prospective observational study set in the general gynaecology clinic of a university teaching hospital between January 2009 and January 2010. PARTICIPANTS/MATERIALS, SETTING, METHODS: There were 985 consecutive women who attended the clinic and underwent structured clinical and transvaginal ultrasound examination in accordance with the study protocol. Morphological features of adenomyosis were systematically recorded with the ultrasound scan to determine its prevalence and factors which may affect its occurrence. MAIN RESULTS AND THE ROLE OF CHANCE: Adenomyosis was present in 206/985 [20.9 (95 CI: 18.523.6)] women included in the study. Multivariate analysis showed that the prevalence of adenomyosis was significantly associated with womens age, gravidity and pelvic endometriosis (P 0.001). In women who subsequently underwent hysterectomy, there was a good level of agreement between the ultrasound and histological diagnosis of adenomyosis [ 0.62 (P 0.001), 95 CI (0.324, 0.912)]. LIMITATIONS, REASONS FOR CAUTION: Our estimate of prevalence of adenomyosis is likely to be higher than in the general population as we studied symptomatic women attending a gynaecology clinic. WIDER IMPLICATIONS OF THE FINDINGS: Better estimates of the prevalence of adenomyosis can improve our understanding of the burden of the disease, help to identify women at high risk of developing the condition and facilitate the development of preventative strategies and effective treatment.