Correlation of adenomyosis features to live birth rates after the first IVF/ICSI treatment, when using the revised Morphological Uterus Sonographic Assessment group definitions.

Introduction: Data regarding the impact of adenomyosis on the outcomes after in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) treatment are conflicting. Standardized diagnostic criteria are prerequisites for studying a potential association between adenomyosis and IVF/ICSI treatment outcomes. This study aims to examine the cumulative live birth rate (CLBR) after the first IVF/ICSI treatment in women with or without direct or indirect features of adenomyosis, using the revised Morphological Uterus Sonographic Assessment (MUSA) group definitions.

Material and methods: This was a prospective cohort study of 1037 women aged 25-≤39 years, undergoing their first IVF/ICSI treatment between January 2019 and October 2022. The presence of MUSA features of adenomyosis was assessed prior to treatment start.

Results: The CLBR after the first IVF/ICSI treatment was 424/1037 (40.9%, 95% CI, 37.9-43.8) in the total cohort. Women with direct features of adenomyosis had lower CLBR, 25/102 (24.5%; 95% CI, 17.5-31.5) than women without, 399/935 (42.7%; 95% CI, 39.5-45.8), p < 0.001. The adjusted relative risk (aRR) for live birth for women with direct features of adenomyosis compared to women without was 0.62 (95% CI, 0.43-0.88), p = 0.007. Direct features were associated with a higher risk of miscarriage after frozen embryo transfer, aRR 2.88 (95% CI, 1.49-5.57), p = 0.002. Women with indirect features had a lower CLBR [50/188 (26.6%, 95% CI, 20.3-32.9)] than women without [399/935, (42.7%, 95% CI, 39.5-45.8)], aRR 0.58 (95% CI, 0.45-0.75), p < 0.001. For features located in the inner myometrium, the aRR for live birth was 0.29 (95% CI 0.11-0.74), p = 0.010 and for the outer myometrium 2.61 (95% CI 1.42-4.8), p = 0.002. An interrupted junctional zone was the single feature that impacted CLBR the most.

Conclusions: The presence of direct or indirect MUSA features of adenomyosis correlates to reduced live birth rates in women undergoing their first IVF/ICSI treatment. Features located in the inner myometrium, particularly an interrupted junctional zone, reduced the chance of live birth the most, whereas location in the outer myometrium was associated with higher chances of live birth. Systematic ultrasound examinations should be considered for women scheduled for IVF/ICSI treatment, for adequate counseling on the chances of successful treatment.