P-473 Adenomyosis progression over time in patients with repeated pregnancy loss: ultrasound-based observations

Abstract Study question Does adenomyosis progress over time in women with two or more pregnancy losses? Summary answer Among women with two or more pregnancy losses, adenomyosis tends to gradually progress over time with notable changes observed in the junctional zone. What is known already Adenomyosis is characterized by the presence of ectopic endometrial tissue (both glands and stroma) within the myometrium. While definitive diagnosis requires histopathological examination of the uterus, uterine imaging such as magnetic resonance imaging (MRI) and transvaginal ultrasound (TVUS) is suggested to detect adenomyosis. The Morphological Uterus Sonographic Assessment (MUSA) consensus group has defined direct and indirect ultrasound signs of adenomyosis. Several factors may contribute to the development of adenomyosis after pregnancy loss, such as trophoblast invasion and disruption of the junctional zone. Study design, size, duration Longitudinal prospective cohort study of women with pregnancy loss, recruited from four Danish public hospitals between November 2020-January 2025. Participants/materials, setting, methods A retrospective analysis of 3D ultrasound uterine volumes, acquired four to eight weeks post-pregnancy loss from 245 women with two or more pregnancy losses, was conducted by two independent sonographers to identify direct and indirect adenomyosis criteria. We compared the prevalence and distribution of MUSA signs between the first to the later scan (following another pregnancy loss) and explored the impact of surgical treatment for the pregnancy loss on adenomyosis development using Chi-squared and Z-tests. Main results and the role of chance The detection of no MUSA direct features was more frequent at first inclusion (5%), compared to later assessments (2%), while the presence of a single direct feature was observed in 54% of cases at initial inclusions, compared to 35% in later inclusions (p-value=0.004). The detection of two direct features became more prevalent at later inclusions (24% vs 46%; p-value=0.004). No significant difference was found in the frequency of indirect MUSA features between the first and later inclusions, despite an overall increase in the number of indirect criteria over time (p-value=0.07). A sub analysis demonstrated a progressive increase in the detection of echogenic buds and lines at the junctional zone over time (26% vs 42%; p-value=0.01) and simultaneously also an enhancement of irregular junctional zone (44% vs 72%; p-value=0.001). Additionally, surgical treatment of the pregnancy loss was significantly correlated with an increased prevalence of echogenic buds and lines at the junctional zone compared to women without surgical treatment (51% vs 31%; p-value=0.026). Limitations, reasons for caution We cannot rule out that the different time intervals between the pregnancy loss and the follow-up visit, where the 3D-volume analysis was undertaken, could impact our results. We are also limited by the absence of dynamical ultrasound evaluation and histopathological confirmation of adenomyosis. Wider implications of the findings These results demonstrate a progressive increase in adenomyosis detection over time and after pregnancy losses in patients with marked differences in the junctional zone assessment and a clinically relevant impact of surgical treatment. These findings highlight the need for further investigation into the link between pregnancy loss and adenomyosis development. Trial registration number No