Differences in effect of copper and ProgestasertR IUDS on fibrinolytic activity of the endometrium in the rabbit.

Rabbits, which have two separate uteri, were used to assess intraindividual differences in the endometrial fibrinolytic activity in the two uteri, one containing a copper IUD and the other a progesterone-releasing IUD (ProgestasertR). A higher activity was demonstrated in the uterus containing the copper-IUD. Enhanced fibrinolytic activity in the endometrium has been held responsible for the increased menstrual blood loss in women using different IUDs. Thus, the present experimental study supports the clinical observation that women using ProgestasertR-IUD have less bleeding complaints than those using copper-IUD.