Adenomyosis is a benign condition of the uterus, defined by the presence of endometrial glands and stroma within the myometrium. Until relatively recently, diagnosis was only possible on histological examination of a uterus following a hysterectomy. This presented many difficulties in accurately assessing the prevalence and clinical significance of adenomyosis. Firstly, it introduced a heavy selection bias as only women with indications for a hysterectomy could be diagnosed with the disease. Reductions in the number of hysterectomies being performed for benign disease (Reid and Mukri, 2005) have amplified this bias, as the population of women from which conclusions are drawn becomes increasingly less representative of the general population. Secondly, the lack of clear and uniform histological criteria raises concerns about the reproducibility of histological diagnosis of adenomyosis. This could also explain the variations in the proportions of women diagnosed with adenomyosis in different studies (Bergholt et al., 2001).

In view of this, it is not surprising that there are no published data on the prevalence of adenomyosis, either in the general population of women or in a general gynaecology clinic setting, as most of the available estimates of prevalence are based on the results of studies of women who underwent hysterectomy (Mehasseb and Habiba, 2009). Continuous improvements in the resolution of transvaginal ultrasound have now enabled a more detailed assessment of uterine architecture. This has facilitated the detection of subtle features of adenomyosis, which could not have been seen with older equipment. Transvaginal ultrasound, along with magnetic resonance imaging (MRI), has recently been shown to have high levels of accuracy in the preoperative diagnosis of adenomyosis (Dueholm, 2006). Transvaginal ultrasound is well tolerated by patients and relative to MRI, it is inexpensive and widely available. The aim of this study therefore was to assess the prevalence of adenomyosis in a population of women attending a general gynaecological clinic by using transvaginal ultrasound.