L26/0-516 Adenomyosis and fertility: are there any differences in adenomyosis type and location in patients with distinct reproductive outcomes?

Abstract Study question Are different adenomyosis subtypes, classified by Morphological Uterus Sonographic Assessment (MUSA) criteria, associated with distinct reproductive outcomes? Summary answer Junctional zone (JZ) involvement and severe adenomyosis were linked to recurrent implantation failure (RIF) and recurrent pregnancy loss (RPL). What is known already Adenomyosis is a common benign gynecological condition among women of reproductive age, with a higher prevalence in infertile populations. While its impact on implantation remains controversial, adenomyosis has been consistently associated with an increased risk of miscarriage and adverse reproductive outcomes. Different pathogenetic mechanisms and lesion localizations within the myometrium, particularly involving the JZ, may impair uterine peristalsis and reproductive function. However, existing evidence is limited by heterogeneous diagnostic approaches and insufficient sonographic characterization according to standardized criteria such as MUSA. Study design, size, duration Retrospective cohort study of 280 women with adenomyosis diagnosed by transvaginal sonography (TVS) at Gynecological Ultrasound Unit of the University of Rome “Tor Vergata”, Italy, between January 2020 and November 2025. The study population was divided in four groups: infertility (IFL), RIF, RPL, and live birth (LB) (70 patients per group). Participants/materials, setting, methods Adenomyosis diagnosis was based on 2D, 3D, power Doppler TVS requiring at least one direct MUSA feature and classified by type, location, and severity. Endocrinological/immunological causes were excluded in RPL, RIF and IFL patients’ group; Only euploid or donor blastocysts were included in patients with RIF. Main results and the role of chance Outer myometrial involvement was more common in patients with LB (94.3%). JZ adenomyosis was statistical significantly associated with RIF and RPL compared to LB (p = 0.0037 and p = 0.001). Severe adenomyosis was more frequent in IFL and RIF patients’ group compared to those with LB (p = 0.01 and p = 0.004). Adenomyosis with endometriosis occurred more in women with IFL and LB than in those with RPL (p = 0.0039 and p = 0.001), whereas isolated adenomyosis predominated in the RPL patients’ group. Post hoc multiple comparisons among the four groups, adjusted using Bonferroni’s correction, revealed that the total inner and outer myometrial, the association with endometriosis and the extension of the disease play an important role in the different reproductive outcome (p<0.05). Involvement of the total JZ was strongly associated with the RPL patients’ group (OR 2.35, 95% CI 1.34–4.12, p = 0.003) and showed an inverse association with the LB patients’ group. Meanwhile, severe adenomyosis was strongly associated with the RIF patients’ group (OR 2.22, 95% CI 1.17–4.22, p = 0.01). Further statistical analysis was performed using adjusted odds ratios (aOR) for age >35 years. After adjustment, the positive association between endometriosis and IFL was no longer significant (p = 0.14) Limitations, reasons for caution Single-center retrospective design and subgroup size may limit generalizability; residual confounding cannot be excluded. Symptoms related to adenomyosis severity were not assessed. As a tertiary endometriosis referral center, selection bias and overestimation of disease prevalence cannot be excluded. Wider implications of the findings Standardized TVS characterization, as recommended by MUSA, seems therefore essential in women trying to achieve a pregnancy, in particular with previous reproductive failures. Precise mapping of disease distribution may not only refine prognostic assessment in women with IFL or RPL, but also inform individualized interventions to maximize pregnancy success. Trial registration number No