Impact of adenomyosis on in vitro fertilization outcomes in women undergoing donor oocyte transfers: a prospective observational study

To prospectively examine the association between adenomyosis type, location, and severity with reproductive outcomes in patients undergoing single embryo transfer (SET) with embryos derived from donor oocytes.A prospective observational cohort study.University-affiliated in vitro fertilization center.Patients with infertility with (n = 114) and without (n = 114) adenomyosis who received their first donor oocyte transfer between January 2019 and January 2023 were included in this study.Adenomyosis was confirmed with the presence of at least one direct feature visualized by 2- or 3-dimensional transvaginal ultrasound and classified according to type (diffuse or focal), localization (inner or outer myometrium and/or junctional zone [JZ]), and uterine extension (mild, moderate, or severe). After an artificial or natural endometrial preparation cycle, patients underwent SET in the blastocyst stage.The primary outcome was the implantation rate. The secondary outcomes were the clinical pregnancy, live birth, and miscarriage rates after SET.The presence of adenomyosis did not significantly affect the implantation, clinical pregnancy, or live birth rates. However, women with adenomyosis had a significantly higher miscarriage rate than those without adenomyosis (35.4% vs. 18.1%, respectively). The multivariate analysis assessed possible risk factors for each clinical outcome considered in the study and showed that adenomyosis affected the risk of miscarriage. Specifically, transvaginal sonography detection of adenomyosis in the JZ was associated with over threefold higher relative risk of miscarriage (relative risk [RR], 3.28; 95% confidence interval [CI], 1.38-7.78). Conversely, adenomyosis features detected exclusively in the outer myometrium were associated with a higher ongoing pregnancy rate (RR, 0.30; 95% CI, 0.13-0.72). Diffuse adenomyosis in the JZ and severe adenomyosis increased the relative risk of miscarriage two-fold (RR, 2.29; 95% CI, 1.22-4.30 and RR, 2.20; 95% CI, 1.19-4.04, respectively).This study demonstrated that although adenomyosis did not significantly reduce the odds of implantation, the direct signs of adenomyosis in the JZ and disease severity are significant risk factors for miscarriage in patients receiving donor oocyte transfers. This study highlights the importance of thorough ultrasound examination and detailed adenomyosis classification in the assessment and management of patients with infertility.