Synthetic progestogen-oestrogen therapy and uterine changes.

Continuous therapy with synthetic progestogen-oestrogen produces marked atrophy of endometrial glands and massive pseudodecidual stromal transformation. Cyclical therapy produces initially a ;frustrated secretory response' with precocious attempts at secretion in poorly developed glands. Pseudodecidua appears about the 20th day. With later cycles there is progressively greater gland atrophy while pseudodecidua is less marked. A possible inductive role of the glands on the stromal response to progestogens is postulated. The effect of different drugs and dosages is discussed. Decidual necrosis may occur with heavy doses. The Arias-Stella reaction, previously regarded as diagnostic of pregnancy, can be produced with ordinary doses of these drugs. Suppression of spiral arterioles is usual. Ballooning of venules is a frequent finding, possibly accounting for breakthrough bleeding. Red degeneration of myomata was present in three of seven hysterectomy specimens containing myomata.