Role of hypoestrogenism or sex steroid antagonism in adhesion formation after myometrial surgery in primates

Objective: To determine the contribution of estrogen in the development of pelvic adhesions during myometrial surgery. Design: A randomized, prospective study in the nonhuman primate. Setting: A primate colony, Department of Obstetrics and Gynecology, Eastern Virginia Medical School. Interventions: All primates were assigned prospectively to one of three treatment groups: [1] GnRH analogue (GnRH-a), [2] mifepristone, or [3] vehicle control. After 3 months of treatment, a standard uterine fundal hysterotomy, for full thickness endometrial biopsy, was performed at the time of exploratory laparotomy, with subsequent scoring of utero-omental adhesions to the hysterotomy site at a future staging procedure based upon adhesion area, vascularity, and tenacity. Serum was drawn on the day of surgery for E(2) determination. Endometrial height, from the surface interface between the endometrium and myometrium, was used as a bioassay of estrogen activity. Results: The hypoestrogenic (GnRH-a) group and the mifepristone group had significantly fewer utero-omental adhesions compared with the normally cycling control monkeys as measured by a lower adhesion score. Similarly, the endometrial thickness was significantly reduced in the GnRH-a and mifepristone groups (one-third) compared with the cycling controls, demonstrating the effects of either hypoestrogenism or noncompetitive estrogen antagonism. Serum E(2) on the day of surgery was predictive of the postoperative adhesion score by both a regression analysis and analysis of covariance. Conclusions: The actions of E(2) seem to have a dramatic effect on the formation of pelvic adhesions after myometrial surgery.