Congenital uterine anomalies are associated with a range of adverse reproductive outcomes but may also be found incidentally. Their significance in women with normal reproductive histories, who do not have a history of recurrent miscarriage or infertility, has been uncertain. The absence of these data has made it difficult to understand the true significance of congenital uterine anomalies found in women with adverse pregnancy outcomes. The advent of transvaginal three-dimensional ultrasonography has enabled the accurate, non-invasive, outpatient diagnosis of congenital uterine anomalies. It has enabled large-scale screening and morphological analysis of congenital uterine anomalies.