Local effects of intrauterine contraceptives placed within the peritoneal cavities of rabbits

Two studies were conducted to evaluate local surface tissue responses to seven different intrauterine contraceptive units placed within the peritoneal cavities of rabbits, either near the uterus or in contact with the hepatic capsule. One or six weeks after insertion, the animals were killed and tissue responses evaluated. All local tissue responses were inflammatory although in some animals tissue responses were also associated with a mechanical component related to pressure of the contraceptive units on the hepatic capsule. Control animals revealed no response. One-week tissue responses among the treated rabbits ranged from minimal to moderate for the Progestasert Intrauterine Progesterone Contraceptive System (IPCS), placebo (nonhormonal) IPCS, Lippes Loop and Saf-T-Coil; moderate for the Dalkon Shield; and severe for the Gyne-T and Cu-7. After six weeks the inflammatory responses to the IPCS, placebo (nonhormonal) IPCS, Lippes Loop and Saf-T-Coil consisted of well-organized fibrous tissue, while the responses to the Gyne-T and Cu-7 were aggressive, invasive and characterized by necrosis and fibroplasia.