gynecology and obstetrics
Abnormal Uterine Bleeding
Pathophysiology of AUB
During ananovulatory cycle,estrogenis produced, but the corpus luteum does not form. Thus, the normal cyclical secretion ofprogesteronedoes not occur, andestrogenstimulates the endometrium unopposed. Without opposition byprogesterone, the endometrium continues to proliferate, eventually outgrowing its blood supply; it then sloughs incompletely and bleeds irregularly and sometimes profusely or for many days. When this abnormal process occurs repeatedly, the endometrium can become hyperplastic, sometimes with atypical or cancerous cells. When abnormal uterine bleeding occurs in patients with ovulatory cycles,progesteronesecretion is prolonged; irregular shedding of the endometrium results, probably becauseestrogenlevels remain low, near the threshold for bleeding (as occurs during menses). In women with obesity, ovulatory AUB can occur ifestrogenlevels are high, resulting in amenorrhea alternating with irregular or prolonged bleeding. Chronic heavy or prolonged uterine bleeding may cause Iron Deficiency Anemia . If AUB is due to ovulatory dysfunction, Ovulatory Dysfunction may also be present. 