20 General Introduction to Adenomyosis Adenomyosis is a prevalent and potentially debilitating benign gynaecological condition characterised by the infiltration of endometrial tissue and stroma into the uterine myometrium. The most commonly associated symptoms are dysmenorrhoea, heavy menstrual bleeding, and subfertility, which can greatly impact quality of life (1,2). The prevalence of adenomyosis as a whole remains unknown and debated, ranging from estimates as low as 5% (3) to as high as 85% (4). This uncertainty stems for a large part from the fact that there exists no consensus on the diagnostic criteria of adenomyosis, and that up to a third of women with adenomyosis are asymptomatic and/or may never present themselves to a clinician (5–7). It is thought that adenomyosis originates in the so-called ‘junctional zone’ (JZ) between the endometrial and myometrial layer of the uterus (see Figure 1.1), where subsequent thickening and irregularity of the JZ characterises adenomyosis. The identification and evaluation of the JZ hence plays a crucial role in the diagnosis and recognition of adenomyosis. Whilst it is commonly accepted that irregularities in the JZ are indicative of adenomyosis, the exact pathophysiological mechanisms behind the disease are still open to discussion. Generally speaking, there are three theories as to the aetiology of adenomyosis: - De novo metaplasia of Mullerian remnants in the myometrium - Tissue injury and active repair (8–10), whereby chronic (micro-) trauma to the JZ and endometrium leads to invagination of endometrium into the myometrium, e.g. due to uterine surgery for example - ‘From outside to inside’ invasion of endometriosis cells into the uterine myometrium (11,12) Adenomyosis Subtypes and Classifications: Adenomyosis is generally accepted to have three subtypes: focal, diffuse and cystic. Focal adenomyosis is concentrated in one area of the myometrium, generally as a single lesion characterised by (heterogenous) thickening of the JZ. Diffuse adenomyosis affects most of the uterus, and results in an enlarged and globular uterus with generally irregular JZ borders.
RkJQdWJsaXNoZXIy MTk4NDMw