Surgically induced endometriosis does not alter peritoneal factors in the rabbit model

Objective: It was the purpose of this study to examine the cause and effect relationship between alterations in peritoneal factors and the presence of ectopic endometrium in the rabbit model. Design: Forty rabbits had autologous endometrial or omental (control) tissue surgically implanted. Peritoneal fluid (PF) volume, macrophage number, and macrophage activation, as well as the number of implants with adhesions, were compared with values obtained during the initial surgery. The effect of hormonal treatment on these factors was evaluated at a third laparotomy. Results: There was a significant increase (P < 0.05) of adhesions in animals with endometrial implants. Peritoneal fluid volume, macrophage number, or macrophage activation were not increased in rabbits with endometrial implants as compared with controls, nor was there a response to hormonal manipulation. Conclusions: These results demonstrate that PF volume, macrophage number, and macrophage activation are not altered by endometrial implants in the rabbit model. This suggests that the increase in these peritoneal factors in women with endometriosis may not be caused exclusively by the presence of ectopic endometrial tissue.