Adenomyosis is a gynaecological disorder with a high prevalence in women of childbearing age and is characterised by the presence of endometrial glands and stroma within the myometrium, associated or not with hypertrophy and hyperplasia of the surrounding myometrium. Adenomyosis may cause pelvic pain and/or abnormal uterine bleeding. Transvaginal ultrasound (TVUS) is considered the main non-invasive diagnostic modality for the diagnosis of adenomyosis. Although adenomyosis is a very common condition among patients of childbearing age, its natural course is still debated. Some studies have evaluated the role of hormonal treatments (systemic or local oestrogen or progestin-based) on adenomyosis, which have been effective in controlling symptoms such as pelvic pain and abnormal uterine bleeding. Despite all this, no evidence is available on the progression of adenomyosis and the factors that may influence its progression over time. The aim of this study is therefore to assess the progression of adenomyosis and associated risk factors using transvaginal ultrasound.