Irregular menstrual periods are usually due to a disturbance in the endocrine axis of the hypothalamus-hypophisis- and the ovaries. Lack of ovulation is the most frequent cause for irregular periods. The pseudo-periods are not even "real" menstrual periods but are, in fact, some type of metrorrhagia (technical term for bleeding). Several diagnostic procedures such as a vaginal examination, ultrasound scan, Pap-test, hormonal analyses, explorative curettage etc. are used to find the correct diagnosis in cases of abnormal vaginal bleeding. The main task of these test is to exclude possible organic reasons for metrorrhagia like tumours, infections, injuries, foreign bodies etc. that are potentially serious. Therapy or prescribed treatment for this condition dependsupon the diagnosis. If an organic cause is excluded, birth control pills are used most often to re-establish regular menstrual cycles for women having trouble with their periods.