Accessory cavitated uterine malformation (ACUM): A scoping review

Introduction: Accessory cavitated uterine malformation (ACUM) is a relatively recent term used to describe a noncommunicating, accessory uterine cavity. ACUM have been published under different terms ranging from juvenile cystic adenomyosis to "uterus-like mass". The objective of this study was to systematically identify all cases of ACUM and definitions described in the literature, regardless of label, and identify morphological, epidemiological, and clinical characteristics as well as management, while also highlighting knowledge gaps. Material and methods: A systematic literature search of three databases was performed, reviewing all records of cystic myometrial lesions. Cases that fitted common definitions for ACUM were included and clinical and imaging characteristics were documented in detail. This work was registered to PROSPERO and reporting followed PRISMA guidelines for scoping reviews. Results: A total of 53 articles were included, comprising 115 cases that met the minimal criteria for ACUM. The median age at onset of symptoms was 17 years, presenting with dysmenorrhea soon after menarche. A total of 19 women were parous. On ultrasound, ACUM appears as unilocular myometrial cysts, usually with ground-glass content. Hemorrhagic content is also observed on magnetic resonance imaging (MRI), with high signal intensity on both T2 and T1-weighted images. Ninety-five (83%) cases were managed surgically, with a trend towards primary nonsurgical options. Although no adverse outcomes were reported, long-term follow-up on subsequent fertility and pregnancy was rare. Conclusions: Despite its increasing recognition as a clinical entity, ACUM often remains underdiagnosed as it shares similarities with other myometrial masses. We propose a unified terminology and definition for ACUM based on the data in this review. ACUM presents as a cavitated lesion, surrounded by a myometrial mantle, in continuity with the anterolateral uterine wall and located beneath the insertion of the round ligament and the interstitial portion of the fallopian tube. In contrast to other uterine abnormalities, a normal uterine cavity is visualized. Future studies are needed, using a clear definition for ACUM, and prospectively investigating management strategies, including long-term follow-up of patient-reported symptoms, fertility, and pregnancy outcomes.