ENDOMETRIAL MORPHOLOGY AND BLEEDING PATTERNS AS A FUNCTION OF PROGESTOGEN SUPPLEMENTATION

Progestogens are added to estrogen replacement therapy for postmenopau sal women to prevent endometrial hyperplasia and adenocarcinoma, and i n sequential therapy to promote a regular and predictable bleed. This protective effect of progestogens is well recognized, but it is not du e to endometrial shedding at a withdrawal bleed and cannot be predicte d from the pattern or timing of the bleed. While irregular bleeding ma y be a reflection of endometrial abnormality and possibly insufficient progestogen, a regular controlled bleed may also occur in the presenc e of endometrial abnormality. A large multicenter study of postmenopau sal women who were taking standard 28-day sequential regimens of estro gen and progestogen found a 2.7% prevalence of complex hyperplasia, an d most of these women had a normal and regular bleeding pattern. Regul ar bleeding may also occur from an atrophic endometrium. Therapy emplo ying a longer cycle with a course of progestogen given every 4 or 4 mo nths may improve patient continuance for long-term therapy. During the estrogen-only phase, the endometrium becomes increasingly proliferati ve, and simple or cystic hyperplasia may develop only after about 12 w eeks, and then can be corrected by progestogen. Women seem to prefer a less frequent withdrawal bleed despite the higher incidence of breakt hrough bleeding compared to a monthly loss. Continuous combined therap y with estrogen and progestogen taken every day causes no withdrawal b leed, though some will have light breakthrough bleeding for the initia l 2 or 3 months. The continuous progestogen. keeps the endometrium atr ophic and also converts preexisting complex endometrial hyperplasia oc curring during sequential therapy to a normal state. As yet, there are no clinical guidelines that can give reassurance about the state of t he endometrium in postmenopausal women who are taking hormone replacem ent therapy.