Abstract
There is considerable worldwide confusion in the use of terminologies and definitions around the symptom of abnormal uterine bleeding (AUB), and these are increasingly leading to difficulties in setting up multinational clinical trials and in interpreting the results of studies undertaken in single centers. In November 2010, the International Federation of Gynecology and Obstetrics formally accepted a new classification system for causes of AUB in the reproductive years. The system, based on the acronym polyps, adenomyosis, leiomyoma, malignancy and hyperplasia - coagulopathy, ovulatory disorders, endometrial causes, iatrogenic, not classified was developed in response to concerns about the design and interpretation of basic science and clinical investigation that relates to the problem of AUB.