Focal adenomyosis is associated with primary infertility.

Objective: To study the association between adenomyosis and infertility, according to the adenomyosis phenotype as diagnosed by magnetic resonance imaging (MRI).

Design: A single-center, cross-sectional study.

Setting: University hospital-based research center.

Patient(s): Patients between 18 and 42 years of age who were surgically explored for benign gynecological conditions at our institution between May 2005 and May 2018. Only women with uterine MRIs performed by a senior radiologist were retained for this study.

Intervention(s): Primary and secondary infertile women were compared with women without infertility. In addition, the women were diagnosed according to the MRI findings as having adenomyosis (focal adenomyosis of the outer myometrium [FAOM] and/or diffuse adenomyosis phenotypes) or no adenomyosis.

Main Outcome Measure(s): Primary and secondary infertility-associated factors.

Result(s): A total of 496 women were included in the study population. Three groups were compared: a no infertility group (n = 361), a primary infertility group (n = 84), and a secondary infertility group (n = 51). Among them, 248 women did not present adenomyosis lesions and 248 women had a radiological diagnosis of adenomyosis. The presence of FAOM was significantly associated with primary infertility. Diffuse adenomyosis was not found to be associated with infertility. The distribution of endometriosis or leiomyomas was not significantly different between the groups. After a multinomial regression model including the women's age and associated endometriosis or leiomyoma, the presence of FAOM was identified as an independent associated factor of primary infertility (adjusted odds ratio 1.9; 95% confidence interval 1.1-3.3).

Conclusion(s): The presence of FAOM was associated with primary infertility. This study opens the door to future clinical and basic studies aimed at better characterization of FAOM and its infertility-related physiopathology.