How Reproducible Are the Ultrasound Features of Adenomyosis Defined by the Revised MUSA Consensus?

Background/Objectives: The aim of this study is to assess the inter- and intra-observer reproducibility of the identification of direct and indirect ultrasonographic features of adenomyosis as defined by the revised Morphological Uterus Sonographic Assessment (MUSA) consensus (2022). Methods: A cohort of 74 women, aged 18 to 45, were recruited from the recurrent miscarriage and general gynaecology clinic at a university-based fertility centre. All the participants underwent 2D and 3D transvaginal Ultrasound scan (TVS) examination in the late follicular and early luteal phase. Conventional grey scale and power Doppler image volumes were acquired and stored. Subsequently, the stored 3D ultrasound images were independently re-evaluated offline by the two observers for the direct and indirect features of adenomyosis as outlined by the revised MUSA group. The intra- and the inter-observer reproducibility was estimated using Cohen's Kappa coefficient. Results: The intra- and interobserver reproducibility (K -0.27, 95% CI 0.06-0.48 and K 0.13, 95% CI -0.10-0.37, respectively) for at least one direct feature of adenomyosis was only modest. Amongst the individual direct features, the interobserver variability of identifying myometrial cysts was fair (K 0.21, 95% CI -0.00-0.42), whereas the intra-observer variability was moderate (K 0.44, 95% CI 0.26-0.63). While hyperechogenic islands identification achieved a fair level of intra- (K 0.31, 95% CI 0.09-0.53) and interobserver (K 0.24, 95% CI 0.01-0.47) agreement, the reproducibility of reporting sub-endometrial lines/buds was fair for the intra-observer (K 0.22, 95% CI -0.02 0.47) and poor for the interobserver (K 0.00, 95% CI -0.20-0.19). The interobserver agreement for indirect features varied from poor to moderate, while the intra-observer agreement ranged between poor to good. Conclusions: The reporting of adenomyosis using direct features suggested by the revised MUSA group consensus showed only modest interobserver and intra-observer agreement. The definitions of ultrasound features for adenomyosis need further refining to enhance the reliability of diagnosis criteria of adenomyosis.