L26/P-543 Ultrasonographic features of adenomyosis and pregnancy outcomes in women with infertility or pregnancy loss: A systematic review and meta-analysis

Abstract Study question Are specific adenomyosis features associated with pregnancy outcomes and what is the prevalence of these features in women with infertility or pregnancy loss? Summary answer We found that diffuse adenomyosis and adenomyosis near the endometrium negatively affected pregnancy outcomes versus no adenomyosis or peripherally located adenomyosis. What is known already Adenomyosis is defined by benign invasion of the endometrium into the myometrium and disruption of the uterine anatomy. Adenomyosis diagnosis is established by ultrasonographic assessment using the revised Morphological Uterus Sonographic Assessment criteria (MUSA). The MUSA criteria can be sub-categorized according to adenomyosis location, diffuse or focal uterine involvement, extent of uterine affection, and the total number of sonographic features present. Previous studies show that sub-categorization according to focal or diffuse adenomyosis, localization close to the endometrium and increasing severity of adenomyosis measured as increased count of individual MUSA features have different impact on clinical pregnancy, miscarriage, and live birth. Study design, size, duration We conducted a systematic review and meta-analysis following PRISMA guidelines combining three search blocks: “Infertility/miscarriage AND adenomyosis AND ultrasonography” on June 26, 2025. Population: Women with infertility or pregnancy loss Exposure: Presence of adenomyosis features Comparator: Absence of adenomyosis features Outcomes: Clinical pregnancy, pregnancy loss, livebirth Studies reporting specific ultrasonographic features of adenomyosis in patients with infertility or pregnancy loss were included. Participants/materials, setting, methods Two independent reviewers completed data extraction. Risk of bias was assessed using the Newcastle-Ottawa Scale for cohort studies reporting pregnancy outcomes and the Joanna Briggs Institute checklist for prevalence studies. Random-effects meta-analyses were conducted, with effect sizes expressed as odds ratios (OR) with 95% confidence intervals (CI). Prevalence estimates were calculated using generalized linear mixed models with a logit link function (PLOGIT). Main results and the role of chance Of 2,006 screened articles, 25 were included in the data synthesis, comprising 15,363 patients, of whom 5,959 had adenomyosis. Diffuse adenomyosis was associated with significantly lower odds of live birth (OR 0.52, 95% CI:0.34-0.79) compared to women without adenomyosis. Diffuse adenomyosis was associated with a trend toward higher pregnancy loss rate (OR 1.27 95% CI:0.54-2.97), as compared with focal adenomyosis. Large uterine volume in women with adenomyosis trended toward lower clinical pregnancy (OR 0.93, 95% CI:0.86-1.01), higher pregnancy loss (OR 2.54, 95% CI:0.51-12.51), and lower live birth rates (OR 0.67, 95% CI:0.42-1.07) compared with women with adenomyosis and small uterine volume. In the qualitative analysis, larger uterine volume as well as adenomyosis features localized near the endometrium (as opposed to peripheral lesions) were associated with poorer reproductive outcomes. Direct versus indirect adenomyosis features or number of features showed no consistent association with adverse pregnancy outcomes. The mean prevalence of MUSA features in study cohorts of infertile women varied considerately between studies: Hyperechogenic islands (29% CI: 8-65%), myometrial cysts (13% CI:5-30%), lines and buds (16% CI:6-39%), asymmetrical wall thickening (37% CI:18-61%), fan-shaped shadowing (12% CI:4-33%), globular uterus (22% CI:4-64%), interrupted junctional zone (76% CI:2-100%), and irregular junction zone (25% CI:0-66%). Limitations, reasons for caution Substantial variation was observed in the prevalence of specific MUSA features. Variability in protocols—including IVF-regimens, embryo-transfer strategies, and donor-oocyte use—limits cross-study comparability. These limitations warrant cautious interpretation of findings. Heterogeneity in study populations and adenomyosis diagnostic criteria may further affect result generalizability. Wider implications of the findings Adenomyosis is a complex condition with pregnancy outcomes varying by specific ultrasonographic features. Researchers should consider reporting individual MUSA features rather than binary adenomyosis presence. The observed variation in adenomyosis feature prevalence among infertile women underscores the need for standardized diagnostic criteria and reporting conventions. Trial registration number Yes