Progestogens versus oestrogens and progestogens for irregular uterine bleeding associated with anovulation

Dysfunctional uterine bleeding (DUB) is excessively heavy, prolonged or frequent bleeding of uterine origin which is not due to pregnancy or to recognisable pelvic or systemic disease. Anovulation may be inferred from a number of observations but, in the normal clinical situation, anovulation is often assumed when a woman presents with heavy, prolonged or frequent bleeding, particularly in those who are at the extremes of reproductive life and in women known to have polycystic ovarian syndrome. Menstrual bleeding that is irregular or excessive is poorly tolerated by the majority of women. Changes in the length of the menstrual cycle generally imply disturbances of the hypothalamo-pituitary-ovarian (HPO) axis. In anovulatory DUB with acyclic (irregular) oestrogen production there will be no progesterone withdrawal from oestrogen primed endometrium and so cycles are irregular. Prolonged oestrogen stimulation may cause a build up of endometrium with erratic bleeding as it breaks down and is expelled. This is the rationale for using cyclical progestogens during the second half of the menstrual cycle, in order to provoke a regular withdrawal bleed. Continuous progestogen is intended to induce endometrial atrophy and hence to prevent oestrogen-stimulated endometrial proliferation. Progestogens, and oestrogens and progestogens in combination are already widely used in the management of irregular or excessive bleeding due to DUB but the regime, dose and type of progestogen used varies widely, with little consensus about the optimum treatment approach.