Uterine fibrinolysis and unilateral insertion of devices in rats.

The validity of a frequently used experimental model for evaluating the effect of different intrauterine devices (IUDs) on uterine fibrinolysis in rodents was investigated in 42 rats. In this model, an IUD is inserted into one horn by a surgical procedure including laparotomy and uterotomy, while the other empty horn is used as a control. In the present investigation, the fibrinolytic activity in different parts of the IUD-containing and control horn was related to the localization of the IUD. The fibrinolytic activity as determined according to Todd's histochemical fibrin slide method was significantly increased in the endometrium in direct contact with the IUD as well as in the uterine segment opposite to the IUD. The enhancement of fibrinolysis in the opposite segment of the control horn was independent of the localization of the IUD, suggesting that neurogenic mechanisms may underlie the stimulation of uterine fibrinolysis in the empty horn. It was concluded that this experimental model is less suitable for evaluating the effect of IUDs on uterine fibrinolysis, since the presence of an IUD in one uterine horn also influences the fibrinolytic activity of the other horn.