gynecology and obstetrics
Vaginal Bleeding
Pathophysiology of Vaginal Bleeding
Most abnormal vaginal bleeding involves Hormonal abnormalities in the hypothalamic-pituitary-ovarian axis Structural (eg, uterine fibroids) or inflammatory (eg, chronic endometritis) disorders Gynecologic cancers Bleeding disorders (uncommon) With hormonal causes, ovulation does not occur or occurs infrequently or irregularly. During an anovulatory cycle, the corpus luteum does not form, and thus the normal cyclical secretion ofprogesteronedoes not occur. Withoutprogesterone,estrogencauses the endometrium to continue to proliferate, eventually outgrowing its blood supply. The endometrium then sloughs and bleeds incompletely, irregularly, and sometimes profusely or for a long time. Structural disorders (eg, uterine fibroids) may cause abnormal bleeding because they interfere with the function of the uterine muscle (myometrium). 